Process for the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid

文档序号：862785 发布日期：2021-03-16 浏览：27次中文

阅读说明：本技术 用于合成(s)-3-氨基-4-(二氟亚甲基)环戊-1-烯-1-甲酸的工艺 (Process for the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid ) 是由理查德·B·西尔弗曼马修·莫斯基托于 2019-05-28 设计创作，主要内容包括：本文提供了用于制备(S)-3-氨基-4-(二氟亚甲基)环戊-1-烯-1-甲酸的工艺、化合物和组合物。本文还提供了含有(S)-3-氨基-4-(二氟亚甲基)环戊-1-烯-1-甲酸的药物组合物。(Provided herein are processes, compounds, and compositions for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid. Also provided herein are pharmaceutical compositions containing (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid.)

1. A process for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a salt thereof, comprising:

converting (1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one (2) to (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4);

converting (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) to (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5);

converting (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5) to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6);

converting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6) to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7);

converting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7) to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8);

(1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) was converted to (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9); and

(S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) is converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), optionally followed by acidification to provide its hydrochloride salt.

2. The process according to claim 1, wherein (1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one (2) is converted into (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3); and (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) is converted into (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4).

3. The process according to claim 1, wherein (1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one (2) is reacted with a.PMBOH, HCl, NaH, THF/DMF; DBDMH, AcOH to produce (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4).

4. The process of claim 1, wherein (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1 ™ ]]Hept-6-yl acetate (4) and a.K₂CO₃Alcohol; and b.2-iodoxybenzoic acid (IBX), MeCN to produce (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]]Hepta-3, 6-dione (5).

5. The process of claim 1, wherein (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1 ™ ]]Hept-6-yl acetate (4) and a.K₂CO₃Alcohol; TPAP, NMO to yield (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]]Hepta-3, 6-dione (5).

6. The process of claim 1 wherein (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Hepta-3, 6-dione (5) with 2- ((difluoromethyl) sulfinyl) pyridine (20), KO^tBu、DMF、NH₄Cl, HCl to give (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [ 2.2.1%]Hept-3-one (6).

7. The process of claim 1 wherein (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Hepta-3, 6-dione (5) with tert-butyllithium and F₂CHP(O)(OEt)₂Reaction to give (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [ 2.2.1%]Hept-3-one (6).

8. The process of claim 1 wherein (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1 ™ ]]Hept-3-one (6) with CAN, MeCN, H₂O to produce (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Hept-3-one (7).

9. The process of claim 1 wherein (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Hept-3-one (7) with Boc₂O、DMAP、Et₃N、CH₂Cl₂Reacted to produce (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxy)Alkylcarbonyl) -2-azabicyclo [2.2.1]Hept-3-one (8).

10. The process of claim 1 wherein (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1 ™ ]]Hept-3-one (8) and K₂CO₃Methanol or ethanol to produce methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate or ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate.

11. The process of claim 1 wherein (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1 ™ ]]Hept-3-one (8) and K₂CO₃Methanol, CH₃ONa is reacted to give methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9).

12. The process according to claim 1, wherein methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate or ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate is reacted with HCl to produce (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) or a pharmaceutically acceptable salt thereof.

13. (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, prepared by the process of claim 1.

14. A process for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a salt thereof, comprising:

converting (1R,4S) - (-) -2-azabicyclo [2.2.1] hept-5-en-3-one (2) to (1R,4S) - (-) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3);

converting (1R,4S) - (-) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) to (1R,4R,6S,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-ylacetate (4);

converting (1R,4R,6S,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) to (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-aza-bicyclo [2.2.1] hept-3-one (25);

converting (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-aza-bicyclo [2.2.1] heptan-3-one (25) to (1R,4R,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5);

converting (1R,4R,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5) to (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6);

converting (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6) to (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7);

converting (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7) to (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8);

converting (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] hept-3-one (8) to (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19); and

(S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (10) is converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), optionally followed by acidification to provide its hydrochloride salt.

15. The process of claim 14, wherein (1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one (2) is reacted with 4-methoxybenzyl chloride, tetrabutylammonium iodide, and lithium bis (trimethylsilyl) amide to produce (1R,4S) - (-) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3).

16. The process of claim 14, wherein (1R,4S) - (-) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) is reacted with 1, 3-dibromo-5, 5-dimethylhydantoin to produce (1R,4R,6S,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-ylacetate (4).

17. The process of claim 14, wherein (1R,4R,6S,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) is reacted with potassium carbonate in methanol to produce (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-aza-bicyclo [2.2.1] hept-3-one (25).

18. The process of claim 14, wherein (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-aza-bicyclo [2.2.1] heptan-3-one (25) is reacted with oxalyl chloride in dichloromethane, DMSO and triethylamine to produce (1R,4R,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5).

19. The process of claim 14 wherein (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-aza-bicyclo [2.2.1] hept-3-one (25) is reacted with 4-methylmorpholine-N-oxide in dichloromethane and tetrapropylammonium perruthenate to produce (1R,4R,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5).

20. The process of claim 14 wherein (1R,4R,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Reaction of hepta-3, 6-dione (5) with 2- ((difluoromethyl) sulfinyl) pyridine (20) and potassium bis (trimethylsilyl) amide in DMF, using NH₄Cl to produce (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [ 2.2.1%]Hept-3-one (6).

21. The process of claim 14, wherein (1) in acetonitrileR,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Hept-3-one (6) with ammonium cerium (IV) nitrate, MeCN, H₂O reaction to produce (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Hept-3-one (7).

22. The process of claim 14 wherein (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Hept-3-one (7) with Boc₂O、DMAP、Et₃N、CH₂Cl₂Reaction to produce (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1]Hept-3-one (8).

23. The process of claim 14 wherein (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1 ™ ]]Hept-3-one (8) and K₂CO₃Methanol or ethanol to produce (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19).

24. The process according to claim 14, wherein (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) is reacted with HCl to produce (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) or a pharmaceutically acceptable salt thereof.

25. (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, prepared by the process of claim 1.

26. (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, prepared by the process according to claim 12.

(1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), or a pharmaceutically acceptable salt thereof.

(1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7) or a pharmaceutically acceptable salt thereof.

Methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (8), or a pharmaceutically acceptable salt thereof.

Methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) or a pharmaceutically acceptable salt thereof.

(S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) or a pharmaceutically acceptable salt thereof.

32. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and one or more of the following compounds: (1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one (2), (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4), (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-3-one (25), (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8), Or (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9), (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-l-ene-1-carboxylate (19), or a pharmaceutically acceptable salt of any of the foregoing.

33. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one (2), or a pharmaceutically acceptable salt thereof.

34. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), or a pharmaceutically acceptable salt thereof.

35. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4), or a pharmaceutically acceptable salt thereof.

36. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4R,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25), or a pharmaceutically acceptable salt thereof.

37. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5), or a pharmaceutically acceptable salt thereof.

38. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), or a pharmaceutically acceptable salt thereof.

39. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), or a pharmaceutically acceptable salt thereof.

40. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8), or a pharmaceutically acceptable salt thereof.

41. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9), or a pharmaceutically acceptable salt thereof.

42. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate, or a pharmaceutically acceptable salt thereof.

43. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid, or a pharmaceutically acceptable salt thereof.

44. A process for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a salt thereof, comprising:

converting cyclopent-3-ene-carboxylic acid ethyl ester (10) to (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11);

converting ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11) to ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12);

converting ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate to ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13);

converting (9S) -ethyl 9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13) to ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14);

converting ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) to ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15); and

(S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

45. The process as claimed in claim 44, wherein cyclopent-3-ene-carboxylic acid ethyl ester (10) is converted to (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11) by Sharpless aminohydroxylation and Boc protection.

46. The process according to claim 44, wherein ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11) is converted by oxidation to ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12).

47. The process according to claim 44, wherein (3R) -ethyl 3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12) is protected and converted to ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13).

48. The process according to claim 44, wherein (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4]]Ethyl nonanecarboxylate (13) was subjected to phenylselenium bromide, base and H₂O₂To produce (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4]]Nonene-7-carboxylic acid ethyl ester (14).

49. The process as claimed in claim 44, wherein ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) is deprotected and subjected to Horner-Wittig reaction to give ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15).

50. The process of claim 44, wherein trifluoroacetic acid (TFA), Dichloromethane (DCM) and saturated NaHCO are used₃(S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

51. (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, prepared by the process of claim 44.

Ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13) or a pharmaceutically acceptable salt thereof.

53. Ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) or a pharmaceutically acceptable salt thereof.

Ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) or a pharmaceutically acceptable salt thereof.

55. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and one or more of the following compounds: cyclopent-3-ene-carboxylic acid ethyl ester (10), (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11), (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylic acid ethyl ester (12), (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13), (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14), (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid ethyl ester (15) Or a pharmaceutically acceptable salt of any of the foregoing.

56. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of cyclopent-3-ene-carboxylic acid ethyl ester (10), or a pharmaceutically acceptable salt thereof.

57. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of cyclopent-3-ene-carboxylic acid ethyl ester (10), (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11), or a pharmaceutically acceptable salt thereof.

58. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12), or a pharmaceutically acceptable salt thereof.

59. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanoate (13), or a pharmaceutically acceptable salt thereof.

60. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14), or a pharmaceutically acceptable salt thereof.

61. A pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1), or a pharmaceutically acceptable salt thereof, and from 0.0001mg to 1mg of ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15), or a pharmaceutically acceptable salt thereof.

Technical Field

Synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid ((S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid).

Background

(S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid is an inhibitor of gamma-aminobutyric acid aminotransferase (GABA-AT) and has been shown to be a possible treatment (treatment) for epilepsy, addiction and hepatocellular carcinoma. See, for example, U.S. patent No. 9,670,141 and Juncosa et al, j.am.chem.soc.2018,140,2151-2164. GABA is an inhibitory neurotransmitter in the Central Nervous System (CNS). When GABA concentration in the brain drops below a threshold level, convulsions may occur. Elevated GABA levels have been shown to stop convulsions. Furthermore, an increase in GABA concentration antagonizes dopamine release from the nucleus accumbens (nucleus accumbens), a region of the hypothalamus associated with reward and motivation, and is considered a possible treatment for addiction. Unfortunately, direct administration of GABA is not feasible because GABA does not cross the blood brain barrier. However, GABA concentration can be increased by inhibiting GABA aminotransferase (GABA-AT). 4-Aminohex-5-enoic acid, also known as vigabatrin (asCommercially available), is currently the only FDA-approved inhibitor of GABA-AT for the treatment of infantile spasms, and has been shown to be a possible treatment of addiction. However, vigabatrin requires large doses (1 g/day-3 g/day), inhibits multiple GABA receptors, and in the case of prolonged use, causes 2Retinal damage in 5% -40% of patients.

In vivo studies in rats indicate that (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid is superior to previous GABA-AT inhibitors in inhibiting dopamine release in the striatum following exposure to cocaine or nicotine. (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid does not inhibit off-target aminotransferases such as alanine aminotransferase and aspartate aminotransferase. In addition, it does not inhibit the hERG potassium channel or various microsomal cytochrome P450 enzymes.

According to the prior art, (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid has been synthesized in six steps from (1S,3S) -3-amino-4- (difluoromethylene) cyclopentane-1-carboxylic acid ((1S,3S) -3-amino-4- (difluoromethylene) cyclopentane-1-carboxylic acid) (also known as CPP-115).

See also, for example, Juncosa et al, j.am. chem.soc., supra, and U.S. patent nos. 7,381,748, 6,794,413, and 9,670,141, each incorporated herein by reference in its entirety.

CPP-115 is an inhibitor of GABA-AT and is currently in clinical trials for the treatment of epilepsy. It has been determined that (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid is 9.8 times more effective as an activator of GABA-AT than CPP-115. Since the synthesis of CPP-115 requires 8 steps, the total synthesis steps from commercial starting materials to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid was counted as 14 steps with a total yield of 3.7%. The synthesis of CPP-115 involves the use of highly flammable t-butyllithium (on the gram scale) to install 1, 1' -difluoroolefin, which limits the scale on which the reaction can be run. Furthermore, existing syntheses rely on the introduction of cyclopentene by selenium oxide elimination. The protected CPP-115 is selenized at 70% yield, although the yield may vary depending on scale. The α -elimination of compound a produces a mixture of chromatographically inseparable isomers in a 5:3 ratio, favoring (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid. Compound B was selectively degraded using thiosalicylic acid to yield (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid alone in an overall yield of 36% from Compound A. Only small batches of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid can be obtained using existing techniques. Furthermore, the production of selenol in the penultimate step complicates the synthesis and purification of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid, since selenium is toxic and is regulated by the FDA to levels below 80-150 μ g/day.

Therefore, there is a need for a process more suitable for large-scale preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid that will reduce cost, reduce the number of preparation steps, reduce hazardous environmental waste, and improve preparation efficiency.

SUMMARY

A process for preparing (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) or a salt thereof is provided, which comprises converting ((1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one) (2) to (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3). (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) is converted into (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4). (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) is converted to (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-3-one (25). (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25) is converted to (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5). (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (6) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) was converted to (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9). (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

(S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is prepared by the process described herein. Described herein are compositions comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1). Described herein are pharmaceutical compositions comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

Provided herein are (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3). Provided herein are compositions comprising (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3). Provided herein are pharmaceutical compositions comprising (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3). (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) is prepared by the process disclosed herein.

Provided herein is (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4). Provided herein are compositions comprising (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4). Provided herein are pharmaceutical compositions comprising (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4). (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) is prepared by the process disclosed herein.

Provided herein is (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25). Provided herein are compositions comprising (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25). Provided herein are pharmaceutical compositions comprising (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25). (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25) is prepared by the process disclosed herein.

Provided herein are (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5). Provided herein are compositions comprising (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5). Provided herein are pharmaceutical compositions comprising (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5). (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) was prepared by the procedure described herein.

Provided herein are (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6). Provided herein are compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (6). Provided herein are pharmaceutical compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (6). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6) was prepared by the procedure described herein.

Provided herein are (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7). Provided herein are compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7). Provided herein are pharmaceutical compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7) was prepared by the procedure described herein.

Provided herein is (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8). Provided herein are compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8). Provided herein are pharmaceutical compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) was prepared by the procedure described herein.

Provided herein is (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9). Provided herein are compositions comprising methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9). Provided herein are pharmaceutical compositions comprising (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9). Methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) was prepared by the process described herein.

Provided herein is (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19). Provided herein are compositions comprising (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19). Provided herein are pharmaceutical compositions comprising (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19). (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) was prepared by the process described herein.

Compositions comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) and (1S,3S) -3-amino-4- (difluoromethylene) cyclopentane-1-carboxylic acid are provided. Pharmaceutical compositions comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) and (1S,3S) -3-amino-4- (difluoromethylene) cyclopentane-1-carboxylic acid are provided.

Compositions are provided comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) and one or more of: (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4), (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-3-one (25), (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-3-one (25), 6-dione (5), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] hept-3-one (6), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] hept-3-one (7), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] hept-3-one (8), (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid methyl ester (9), Or (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-l-ene-1-carboxylic acid (19).

A process for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is provided, which comprises converting cyclopent-3-ene-carboxylic acid ethyl ester (10) to (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11). (3R,4S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11) was converted into ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12). (3R) -ethyl 3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate was converted to ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13). (9S) -9- (tert-Butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13) was converted into (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14). (S) -ethyl 9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) was converted to ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15). (S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

Provided herein is ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11). Provided herein are compositions comprising ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11). Provided herein are pharmaceutical compositions comprising ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11). Ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11) was prepared by the process described herein.

Provided herein is ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12). Provided herein are compositions comprising ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12). Provided herein are pharmaceutical compositions comprising ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12). Ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12) was prepared by the process described herein.

Provided herein is ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13). Provided herein are compositions comprising ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanoate (13). Provided herein are pharmaceutical compositions comprising ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanoate (13). (9S) -9- (tert-Butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13) was prepared by the process described herein.

Provided herein is ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14). Provided herein are compositions comprising ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14). Provided herein are pharmaceutical compositions comprising ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14). (S) -9- (tert-Butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14) was prepared by the process described herein.

Provided herein is ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15). Provided herein are compositions comprising ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15). Provided herein are pharmaceutical compositions comprising ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15). Ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) was prepared by the process described herein.

Compositions are provided comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) and one or more of: cyclopent-3-ene-carboxylic acid ethyl ester (10), (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11), (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylic acid ethyl ester (12), (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13), (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14) or (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid ethyl ester (15) .

Brief Description of Drawings

FIG. 1 is (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] benzene]500MHz of hept-3-one (6)¹H NMR Spectroscopy (CDCl)₃)。

FIG. 2 is (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] benzene]Process for producing hept-3-one (6)¹³C NMR Spectroscopy (CDCl)₃；126MHz)。

FIG. 3 is (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] benzene]127.5MHz of hept-3-one (6)¹⁹F NMR Spectroscopy (CDCl)₃)。

FIG. 4 is (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] lanes]500MHz of hept-3-one (7)¹H NMR Spectroscopy (CDCl)₃)。

FIG. 5 is (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] lanes]Process for producing hept-3-one (7)¹³C NMR Spectroscopy (CDCl)₃；126MHz)。

FIG. 6 is (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] lanes]127.5MHz of hept-3-one (7)¹⁹F NMR Spectroscopy (CDCl)₃)。

FIG. 7 is 500MHz of (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9)¹H NMR Spectroscopy (CDCl)₃)。

FIG. 8 is a drawing of (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9)¹³C NMR Spectroscopy (CDCl)₃；126MHz)。

FIG. 9 is 127.5MHz of (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9)¹⁹F NMR spectrum.

FIG. 10 is (S) -3-amino-4- (difluoromethylene) cyclopent-1-en-1-yl-500MHz of formic acid (1)¹H NMR Spectroscopy (CDCl)₃)。

FIG. 11 is a drawing of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1)¹³C NMR Spectroscopy (CDCl)₃；126MHz)。

FIG. 12 is 127.5MHz of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1)¹⁹F NMR spectrum.

Detailed description of the invention

Provided herein are processes, compounds, and compositions for preparing (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1). The process herein is scalable and high yield compared to the prior art, avoids the use of selenium and tert-butyllithium, and avoids the formation of multiple isomers from alpha-elimination. In embodiments, the process herein comprises elimination of the leaving group from the β -position, exclusion of the resulting isomeric mixture, reduction of the number of synthetic steps from 14 to 9 and increase of the yield from 3.7% to 8.1% compared to the prior art.

In embodiments, the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is shown in scheme 1, starting with ((1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one) (2).

Scheme 1

AC ═ acetyl, PMB ═ 4-methoxybenzyl, PG ═ protecting group

According to scheme 1, there is provided a process for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) or a salt thereof, which comprises converting ((1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one) (2) to (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3). (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) is converted into (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4). (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) is converted to (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5). (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) was converted to (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9). (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

In embodiments, the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is shown in scheme 1A.

Scheme 1A

Abbreviations: PMBOH: 4-methoxybenzyl alcohol; DMF: n-dimethylformamide; DBDMH: 1, 3-dibromo-5, 5-dimethylhydantoin; TPAP: tetrapropylammonium perruthenate; NMO: n-methylmorpholine N-oxide; CAN: ammonium cerium nitrate; DMAP: n, N-dimethylaminopyridine

In embodiments, from ((1R,4S) -2-azabicyclo [ 2.2.1)]Hept-5-en-3-one) (2) (also known as Vince lactam) was started and the literature procedure was followed with modifications such as using PMBOH/HCl (see Qiu, j.; silverman, R.B.J.Med.chem.2000,43,706-720), obtaining (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] on a multi-gram scale (multi-gram scale)]Hept-6-yl acetate (4) (scheme 1A): PMBOH, HCl, NaH, THF/DMF; DBDMH, AcOH. Alcoholysis and oxidation of acetate esters in two steps to give the ketone (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [ 2.2.1%]Hepta-3, 6-dione (5): c.K₂CO₃Alcohol; a mixture of tpap, NMO,MS，CH₂Cl₂. The foregoing allows for difluoro-Horner-Wadsworth-Emmons olefination of ketone 5. When 2- ((difluoromethyl) sulfinyl) pyridine (20) (also known as Hu reagent) is reacted with KO as a base^tBu when used together, gives (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]]Hept-3-one (6): e.2- ((difluoromethyl) sulfinyl) pyridine (20), KO^tBu, DMF, then NH₄Cl, then HCl. Alternatively, e may be t-butyllithium and F₂CHP(O)(OEt)₂(see Pan, Y.; Qiu, J.; Silverman, R.B.J.Med.chem.2003,46, 5292-. The next step is alcoholysis and elimination of the lactam. Reacting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Deprotection of hept-3-one (6) to give (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]]Hept-3-one (7): can, MeCN, H₂And O. Small amounts of 4-methoxybenzoyl protected lactam may also be isolated. Lactam (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Boc protection of hept-3-one (7) gives (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1]Hept-3-one (8): boc₂O，DMAP，Et₃N，CH₂Cl₂. (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1]K for hept-3-one (8)₂CO₃And alcoholysis of an alcohol resulting in the subsequent elimination of bromide via two steps to yield methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate or ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9): h.K₂CO₃Alcohol, an alcohol. Final deprotection in HCl to give (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) with no observable isomerization or degradation: hcl, dioxane. Although methanol is shown in the schematic above, it should be understood that an alcohol such as ethanol or propanol may be used as the alcohol.

In embodiments, from ((1R,4S) -2-azabicyclo [ 2.2.1)]Hept-5-en-3-one) (2) (Vince lactam) was started and (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] obtained on a multi-gram scale, for example using PMBOH/HCl, following a modification of the literature procedure (see, Qiu et al, supra)]Hept-6-yl acetate (4) (scheme 1A): PMBOH (1-2 equiv.), HCl, NaH (0.8-1.5 equiv.) 0 deg.C-5 deg.C, THF/DMF (0.75-1.5:0.75-1.5), 4h-8 h; DBDMH (0.4-0.8 equivalent), AcOH, 15-30 ℃ and 4-8 h; methanolysis and oxidation of acetate esters produces the ketone (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] in two steps]Hepta-3, 6-dione (5): c.K₂CO₃(2-4 equiv.), MeOH 0.5h-2 h; TPAP (0.001-0.2 equivalent), NMO (1.0-3.0 equivalent),MS，CH₂Cl₂15h-25 h. The foregoing allows for difluoro-Horner-Wadsworth-Emmons olefination of ketone 5. When 2- ((difluoromethyl) sulfinyl) pyridine (20) (Hu reagent) is reacted with KO as base^tBu when used together, gives (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]]Hept-3-one (6), e.g. with NH₄Cl/6M HCl quench the base was injected over 15 minutes to 2 hours: e.2- ((difluoromethyl) sulfinyl) pyridine (20) (1.0-1.5 equiv.), KO^tBu (1.25-1.75 equivalent), DMF, -80 deg.C-40 deg.C, 15min-60min, then NH₄Cl, then HCl, then 15-30 ℃, then 40-80 ℃,1 h. Alternatively, e may be t-butyllithium and F₂CHP(O)(OEt)₂(see, Pan, Y, et al, supra). The next step is methanolysis and elimination of the lactam. Reacting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Deprotection of hept-3-one (6) to give (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]]Hept-3-one (7): can (2-4 equivalents), MeCN, H₂O, the temperature of-10 ℃ to 10 ℃ is 0.75h-2 h. Small amounts of 4-methoxybenzene can also be isolatedAcyl protected lactams. Lactam (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Boc protection of hept-3-one) (7) gives (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [ 2.2.1%]Hept-3-one (8): boc₂O (1.0-1.5 equiv.), DMAP (0.01-0.5 equiv.), Et₃N (1.0-2.0 equiv.), CH₂Cl₂0.5h-2.0 h. (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1]K for hept-3-one (8)₂CO₃And methanolysis of methanol, resulting in the subsequent elimination of bromide in two steps to produce methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate: h.K₂CO₃(2-4 equiv.), MeOH, 4h-8 h. Final deprotection in 6M HCl at 70 ℃ to 90 ℃ yielded (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) with no observable isomerization or degradation: hcl (6M), dioxane, 70 ℃ to 90 ℃,1h to 3 h.

In embodiments, from ((1R,4S) -2-azabicyclo [ 2.2.1)]Hept-5-en-3-one) (2) (Vince lactam) was started and (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [ 2.2.1) obtained on a multi-gram scale following a modification of literature procedures, such as using PMBOH/HCl (see Qiu, j., et al, supra)]Hept-6-yl acetate (4) (scheme 1A): PMBOH (11.5 equiv.), HCl, NaH (1.1 equiv.), THF/DMF (1:1) at 0 ℃, 6h, 73%; DBDMH (0.6 equiv.), AcOH, 23 ℃, 6h, 90%; methanolysis and oxidation of acetate esters produces the ketone (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] in two steps]Hepta-3, 6-dione (5): c.K₂CO₃(3 eq), MeOH, 1 h; TPAP (0.01 equiv.), NMO (2.0 equiv.),MS，CH₂Cl₂18h, 52 percent. The foregoing provides a form of running these steps on a multi-gram scale, allowing for difluoro-Horner-Wadsworth-Emmons olefination of ketone 5. When 2- ((difluoromethyl) sulfinyl) pyridine (20) (Hu reagent) is reacted with KO as base^tBu, using the conditions reported for Hu (see Zhao, y.; Huang, w.; Zhu, l.; Hu,j. org. Lett.2010,12, 1444-one 1447) when used together, (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] ring]Hept-3-one (6) is obtained in a small amount<10% yield). Slowly injecting alkali in 30min, using NH₄Cl/6M HCl quenched, increasing the yield significantly to 45%. Extending the injection of base to 1 hour increased the yield to 58%. See table 1 below. The reaction is not greatly affected on a large scale, allowing scale-up to 3.5g of (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]]Hepta-3, 6-dione (5), yield was not decreased: e.2- ((difluoromethyl) sulfinyl) pyridine (20) (1.2 equiv.), KO^tBu (1.5 eq), DMF, -60 ℃,30 min, then NH₄Cl, then 6M HCl, then 23 ℃, then 60 ℃,1 h. Alternatively, e may be t-butyllithium and F₂CHP(O)(OEt)₂(see, Pan, et al, supra). The next step is methanolysis and elimination of the lactam. Reacting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Deprotection of hept-3-one (6) to give (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] in 80% yield]Hept-3-one (7): can (3 equivalents), MeCN, H₂O, 0 ℃ for 1 h. Small amounts of 4-methoxybenzoyl protected lactam may also be isolated. Lactam (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Boc protection of hept-3-one) (7) gives (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [ 2.2.1%]Hept-3-one (8): boc₂O (1.2 equiv.), DMAP (0.1 equiv.), Et₃N (1.5 eq), CH₂Cl₂And 1 h. (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1]K for hept-3-one (8)₂CO₃And methanolysis of methanol, resulting in the subsequent elimination of bromide, to produce methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9): h.K₂CO₃(3 equiv.), MeOH, 6h, 52% over two steps. Final deprotection in 6M HCl at 80 ℃ yielded (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) in 97% yield with no observable isomerization or degradation: hcl (6M), dioxane, 80 ℃,2 h. In general terms, the amount of the solvent to be used,the yield from Vince lactam (2) to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) was 8.1%.

TABLE 1 fluorination^aIs optimized

^aConditions are as follows: 5(1 equiv.), 20(1.2 equiv.), DMF (0.3M), -60 ℃ and then KO in DMF^tBu (1.5 eq) (0.5M), then quenched at-60 ℃, then 23 ℃, then 60 ℃ for 1 h;^btime before addition of quenching solution;^cisolated yield after chromatography.

In embodiments, without wishing to be bound by any theory, the following is a proposed mechanism for fluorination of (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5):

as indicated above, various intermediates are formed during the course of the fluorination reaction. The first formed intermediate 21 rearranges via the cyclic intermediate 22 to form the sulfonate 23, and then the sulfonate 23 is protonated, triggering elimination and olefin formation (see above). If KO is added to the mixture of 5 and 20^tAfter 5min after Bu, the reaction was quenched with 6M HCl at-60 ℃ and only 21 was observed by LC/MS (entry 1, table 1). Adding KO^tBu, then 6M HCl quench at-60 ℃ (entry 2, table 1), and subsequent heating at 60 ℃ for 1h, provided 6 in 9% yield with starting material and intermediate 21. With saturated NH₄After 1 hour of quenching of the Cl solution, it was then quenched with 6M HCl, slightly increasing the yield (entry 3, table 1). Slowly injecting alkali with injection pump within 30min, and adding NH₄The Cl/6M HCl was quenched,the yield was increased significantly to 45%. Extending the injection of base to 1 hour increased the yield to 58%.

In embodiments, the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is shown in scheme 2.

Scheme 2

The racemic synthesis yield (%) is provided relative to the(s) -isomer yield (%).

Abbreviations: LiHMDS: lithium bis (trimethylsilyl) amide; THF: tetrahydrofuran; PMB: 4-methoxybenzyl; DBDMH: 1, 3-dibromo-5, 5-dimethylhydantoin; TPAP: tetrapropylammonium perruthenate; CAN: ammonium cerium nitrate; DMAP: n, N-dimethylaminopyridine

According to scheme 2, there is provided a process for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) or a salt thereof, which comprises converting ((1R,4S) -2-azabicyclo [2.2.1] hept-5-en-3-one) (2) to (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3). (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) is converted into (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4). (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) is converted to (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-3-one (25). (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25) is converted to (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5). (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3, 6-dione (5) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7) is converted to (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8). (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) was converted to (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19). (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

In embodiments, the following compounds are provided:

(1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3)

(1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4)

(1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25)

(1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5)

(1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6)

(1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7)

(1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8)

(S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9)

(S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19)

In embodiments, provided herein are compositions comprising (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. Compositions comprising (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), or a salt thereof, can comprise a polar solvent, such as water (aquous), methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) or a pharmaceutically acceptable salt thereof can be a pharmaceutical composition. The composition may comprise (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) or a salt thereof can comprise a polar solvent, e.g., water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) or a pharmaceutically acceptable salt thereof can be a pharmaceutical composition. The composition may comprise (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. Compositions comprising (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25), or a salt thereof, can comprise a polar solvent, e.g., water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25), or a pharmaceutically acceptable salt thereof, can be a pharmaceutical composition. The composition may comprise (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) or a salt thereof may comprise a polar solvent, such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) or a pharmaceutically acceptable salt thereof can be a pharmaceutical composition. The composition may comprise (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. Compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), or a salt thereof, can comprise a polar solvent, e.g., water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), or a pharmaceutically acceptable salt thereof, can be a pharmaceutical composition. The composition may comprise (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), or a salt thereof, in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), or a salt thereof, can comprise a polar solvent, e.g., water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), or a pharmaceutically acceptable salt thereof, can be a pharmaceutical composition. The composition may comprise (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), or a salt thereof, in an amount from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) or a salt thereof may comprise a polar solvent such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8), or a pharmaceutically acceptable salt thereof, can be a pharmaceutical composition. The composition may comprise (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) or a salt thereof may comprise a polar solvent such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) or a pharmaceutically acceptable salt thereof may be a pharmaceutical composition. The composition may comprise (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise the following amount of (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9), or a pharmaceutically acceptable salt thereof: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. The composition comprising (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) or a salt thereof may comprise a polar solvent such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) or a pharmaceutically acceptable salt thereof may be a pharmaceutical composition. The composition may comprise (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is shown in scheme 3, starting with cyclopent-3-ene-carboxylic acid ethyl ester (10).

Scheme 3

As depicted in scheme 3, a process for the preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is provided, which comprises converting cyclopent-3-ene-carboxylic acid ethyl ester (10) to (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11). (3R,4S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11) was converted into ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12). (3R) -ethyl 3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate was converted to ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13). (9S) -9- (tert-Butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13) was converted into (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14). (S) -ethyl 9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) was converted to ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15). (S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

In embodiments, the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) is shown in scheme 3A.

Scheme 3A

In embodiments, as shown in scheme 3A, cyclopent-3-ene-carboxylic acid ethyl ester (10) (commercially available from Sigma Aldrich, st. louis, MO) is converted to (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11) by Sharpless aminohydroxylation and Boc protection. Using OsO₄As catalysts, by salts of olefins with N-halosulfonamides, N-haloacylReaction of salts of amines with salts of N-halocarbamates, Sharpless aminohydroxylation allows for the selective preparation of 1, 2-aminoalcohols. Enantioselectivity is achieved by the addition of dihydroquinine-derived and dihydroquinidine-derived chiral ligands. Oxidation of ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11) yielded ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12). Conversion of ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12) to (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4]]Nonanecarboxylic acid ethyl ester (13). Reacting (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4]]Ethyl nonanecarboxylate (13) was subjected to phenylselenium bromide, base and H₂O₂To produce (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4]]Nonene-7-carboxylic acid ethyl ester (14). (S) -9- (tert-Butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4]Nonene-7-carboxylic acid ethyl ester (14) was deprotected and subjected to Horner-Wittig reaction to give (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid ethyl ester (15). The Horner-Wittig reaction involves the reaction of an aldehyde or ketone with a stable phosphorus ylide (phosphonate carbanion) and results in an olefin with E-selectivity. With trifluoroacetic acid (TFA), Dichloromethane (DCM) and saturated NaHCO₃(S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) was converted to (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1).

In embodiments, the following compounds are provided:

(3R,4S) -3- ((tert-Butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11)

(3R) -3- ((tert-Butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylic acid ethyl ester (12)

(9S) -9- (tert-Butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13)

(S) -9- (tert-Butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14)

(S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15)

In embodiments, provided herein are compositions comprising ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11), or a salt thereof, may comprise a polar solvent, such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11), or a pharmaceutically acceptable salt thereof, may be a pharmaceutical composition. The composition may comprise ethyl (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11), or a salt thereof, in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (3R,4S) -ethyl 3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylate (11), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising (3R) -ethyl 3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. Compositions comprising ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12), or a salt thereof, may comprise a polar solvent, such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12) or a pharmaceutically acceptable salt thereof may be a pharmaceutical composition. The composition may comprise ethyl (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12), or a salt thereof, in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise (3R) -ethyl 3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylate (12), or a pharmaceutically acceptable salt thereof, in the following amounts: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanoate (13) or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13) or a salt thereof may comprise a polar solvent such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13) or a pharmaceutically acceptable salt thereof may be a pharmaceutical composition. The composition may comprise ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylate (13) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise the following amount of ethyl (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanoate (13) or a pharmaceutically acceptable salt thereof: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) or a salt thereof may comprise a polar solvent such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) or a pharmaceutically acceptable salt thereof may be a pharmaceutical composition. The composition may comprise ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise the following amount of ethyl (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylate (14) or a pharmaceutically acceptable salt thereof: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, provided herein are compositions comprising ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15), or a salt thereof. Such compositions may comprise a reaction mixture, such as those described herein. A composition comprising ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) or a salt thereof may comprise a polar solvent such as water, methanol, ethanol, DMF, acetic acid, and the like; or a non-polar solvent such as diethyl ether, hexane, dichloromethane, ethyl acetate, and the like. The composition comprising ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) or a pharmaceutically acceptable salt thereof may be a pharmaceutical composition. The composition may comprise ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) or a salt thereof in an amount of from 0.0001mg to 50mg or more. For example, the pharmaceutical composition may comprise the following amount of ethyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (15) or a pharmaceutically acceptable salt thereof: greater than 0.0001mg, e.g., from 0.0001mg to 0.0002mg, 0.0001mg to 0.0003mg, 0.0002mg to 0.0003mg, 0.0003mg to 0.0004mg, 0.0004mg to 0.0005mg, 0.0005mg to 0.0006mg, 0.0006mg to 0.0007mg, 0.0007mg to 0.0008mg, 0.0008mg to 0.0009mg, 0.0009mg to 0.001mg, 0.001mg to 0.002mg, 0.002mg to 0.003mg, 0.003mg to 0.004mg, 0.004mg to 0.005mg, 0.005mg to 0.006mg, 0.006mg to 0.007mg, 0.007mg to 0.008mg, 0.008mg to 0.009mg, 0.009mg to 0.01mg, 0.01mg to 0.01mg, 0.006mg to 0.03mg, 0.04mg to 0.09mg, 0.06mg to 0.06mg, 0.06mg to 0.0.7 mg, 0.7mg, 0.0.0.7 mg to 0.7mg, 0.06mg to 0.7mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7mg to 0.7mg, 0.06mg, 0.7 to 0., 6.0mg to 7.0mg, 7.0mg to 8.0mg, 8.0mg to 9.0mg, or 9.0mg to 10 mg.

In embodiments, the pharmaceutical composition may comprise (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof in the following amounts: for example, about 0.001 to 500mg, 0.01 to 450mg, 0.01 to 300mg, 0.01 to 250mg, 0.01 to 200mg, 0.01 to 175mg, 0.01 to 150mg, 0.01 to 125mg, 0.01 to 100mg, 0.01 to 75mg, 0.01 to 50mg, 0.01 to 30mg, 0.01 to 25mg, 0.01 to 20mg, 0.01 to 15mg, 0.01 to 10mg, 0.01 to 5mg, 0.01 to 1mg, 0.025 to 500mg, 0.025 to 450mg, 0.025 to 300mg, 0.025 to 250mg, 0.025 to 200mg, 0.175 to 025mg, 0.025 to 150mg, 0.05 to 500mg, 0.05 to 200mg, 0.025 to 0.05 to 200mg, 0.05 to 0.025mg, 0.05 to 200mg, 0.025mg, 0.05 to 0.025mg, 0.025mg to 25mg, 0.05 to 25mg, 0.025mg, 0.05 to 25mg, 0.05mg, 0.025mg, 0.05 to 25mg, 0.025mg to 10mg, 0.025mg to 5mg, 0.025mg, 0.05 to, 0.05 to 150mg, 0.05 to 125mg, 0.05 to 100mg, 0.05 to 75mg, 0.05 to 50mg, 0.05 to 30mg, 0.05 to 25mg, 0.05 to 20mg, 0.05 to 15mg, 0.05 to 10mg, 0.05 to 5mg, 0.05 to 1mg, 0.075 to 500mg, 0.075 to 450mg, 0.075 to 300mg, 0.075 to 250mg, 0.075 to 200mg, 0.075 to 175mg, 0.075 to 150mg, 0.075 to 125mg, 0.075 to 100mg, 0.075 to 75mg, 0.075 to 50mg, 0.075 to 30mg, 0.075 to 25mg, 0.075 to 20mg, 0.075 to 15mg, 0.05 to 125mg, 0.0.to 1.1 to 1.1 mg, 0.1 to 1.1 mg, 0.075 to 1mg, 0.1 to 1.1 mg, 0.075 to 1mg, 0.1 to 200mg, 0.075 to 1mg, 0.1 to 1mg, 1 to 1mg, 0.1 to 1mg, 1 to 1mg, 0.1 to 25mg, 0.1 to 1mg, 0.1 to 1mg, 0 to 25mg, 0, 0.1 to 20mg, 0.1 to 15mg, 0.1 to 10mg, 0.1 to 5mg, 0.1 to 1mg, 0.25 to 500mg, 0.25 to 450mg, 0.25 to 300mg, 0.25 to 250mg, 0.25 to 200mg, 0.25 to 175mg, 0.25 to 150mg, 0.25 to 125mg, 0.25 to 100mg, 0.25 to 75mg, 0.25 to 50mg, 0.25 to 30mg, 0.25 to 25mg, 0.25 to 20mg, 0.25 to 15mg, 0.25 to 10mg, 0.25 to 5mg, 0.25 to 1mg, 0.5 to 500mg, 0.5 to 450mg, 0.5 to 300mg, 0.5 to 250mg, 0.5 to 5mg, 0.25 to 5mg, 0.5 to 5mg, 0.25 to 5mg, 0.25 to 5mg, 0.5 to 5mg, 0.25 to 5mg, 0.25 to 5mg, 0.5 to 5mg, 0.25mg, 0.5 to 5mg, 0.5 to 5mg, 0.5mg, 0.25mg, 0, 1mg to 300mg, 1mg to 250mg, 1mg to 200mg, 1mg to 175mg, 1mg to 150mg, 1mg to 125mg, 1mg to 100mg, 1mg to 75mg, 1mg to 50mg, 1mg to 30mg, 1mg to 25mg, 1mg to 20mg, 1mg to 15mg, 1mg to 10mg, 1mg to 5mg, 1mg to 4mg, 1mg to 3mg, 1mg to 2mg, 2mg to 500mg, 2mg to 450mg, 2mg to 300mg, 2mg to 250mg, 2mg to 200mg, 2mg to 175mg, 2mg to 150mg, 2mg to 125mg, 2mg to 100mg, 2mg to 75mg, 2mg to 50mg, 2mg to 30mg, 2mg to 25mg, 2mg to 20mg, 2mg to 15mg, 2mg to 10mg, 2mg to 5mg, 3mg to 500mg, 3mg to 150mg, 3mg to 200mg, 3mg to 250mg, 3mg to 25mg, 3mg to 175mg, 3mg to 15mg, 3mg to 25mg, 1mg to 15mg, 1mg to 5mg, 1mg to 5mg, 3mg to 100mg, 3mg to 75mg, 3mg to 50mg, 3mg to 30mg, 3mg to 25mg, 3mg to 20mg, 3mg to 15mg, 3mg to 10mg, 3mg to 5mg, 4mg to 500mg, 4mg to 450mg, 4mg to 300mg, 4mg to 250mg, 4mg to 200mg, 4mg to 175mg, 4mg to 150mg, 4mg to 125mg, 4mg to 100mg, 4mg to 75mg, 4mg to 50mg, 4mg to 30mg, 4mg to 25mg, 4mg to 20mg, 4mg to 15mg, 4mg to 10mg, 4mg to 5mg, 5mg to 500mg, 5mg to 450mg, 5mg to 300mg, 5mg to 250mg, 5mg to 200mg, 5mg to 175mg, 5mg to 150mg, 5mg to 125mg, 5mg to 100mg, 5mg to 75mg, 5mg to 50mg, 5mg to 10mg, 5mg to 25mg, 5mg to 25mg, 4mg to 25mg, 4mg, 10mg to 450mg, 10mg to 300mg, 10mg to 250mg, 10mg to 200mg, 10mg to 175mg, 10mg to 150mg, 10mg to 125mg, 10mg to 100mg, 10mg to 75mg, 10mg to 50mg, 10mg to 30mg, 10mg to 25mg, 10mg to 20mg, 10mg to 15mg, 15mg to 500mg, 15mg to 450mg, 15mg to 300mg, 15mg to 250mg, 15mg to 200mg, 15mg to 175mg, 15mg to 150mg, 15mg to 125mg, 15mg to 100mg, 15mg to 75mg, 15mg to 50mg, 15mg to 30mg, 15mg to 25mg, 15mg to 20mg, 20mg to 500mg, 20mg to 450mg, 20mg to 300mg, 20mg to 250mg, 20mg to 200mg, 20mg to 175mg, 20mg to 150mg, 20mg to 125mg, 20mg to 100mg, 20mg to 25mg, 20mg, 25mg, 20mg to 25mg, 10mg to 25mg, 25mg to 300mg, 25mg to 250mg, 25mg to 200mg, 25mg to 175mg, 25mg to 150mg, 25mg to 125mg, 25mg to 100mg, 25mg to 80mg, 25mg to 75mg, 25mg to 50mg, 25mg to 30mg, 30mg to 500mg, 30mg to 450mg, 30mg to 300mg, 30mg to 250mg, 30mg to 200mg, 30mg to 175mg, 30mg to 150mg, 30mg to 125mg, 30mg to 100mg, 30mg to 75mg, 30mg to 50mg, 40mg to 500mg, 40mg to 450mg, 40mg to 400mg, 40mg to 250mg, 40mg to 200mg, 40mg to 175mg, 40mg to 150mg, 40mg to 125mg, 40mg to 100mg, 40mg to 75mg, 40mg to 50mg, 50mg to 500mg, 50mg to 450mg, 50mg to 300mg, 50mg to 250mg, 50mg to 125mg, 50mg to 100mg, 50mg to 100mg, 75mg to 500mg, 75mg to 450mg, 75mg to 300mg, 75mg to 250mg, 75mg to 200mg, 75mg to 175mg, 75mg to 150mg, 75mg to 125mg, 75mg to 100mg, 100mg to 500mg, 100mg to 450mg, 100mg to 300mg, 100mg to 250mg, 100mg to 200mg, 100mg to 175mg, 100mg to 150mg, 100mg to 125mg, 125mg to 500mg, 125mg to 450mg, 125mg to 300mg, 125mg to 250mg, 125mg to 200mg, 125mg to 175mg, 125mg to 150mg, 150mg to 500mg, 150mg to 450mg, 150mg to 250mg, 150mg to 200mg, 200mg to 500mg, 200mg to 450mg, 200mg to 300mg, 200mg to 250mg, 250mg to 500mg, 250mg to 450mg, 250mg to 300mg, 300mg to 300mg, 350mg to 500mg, 350mg to 350mg, 350mg to 450mg, 350mg to 300mg, 350mg to 500mg, 400mg, 300mg to 450mg, 100mg to 200mg, 100mg to 250mg, 100mg to 200mg, 100mg to 175mg, 400mg to 500mg, 400mg to 450mg, of which 0.01mg, 0.025mg, 0.05mg, 0.075mg, 0.1mg, 0.25mg, 0.5mg, 0.75mg, 1mg, 2mg, 2.5mg, 3mg, 4mg, 5mg, 7.5mg, 10mg, 12.5mg, 15mg, 17.5mg, 20mg, 22.5mg, 25mg, 30mg, 35mg, 40mg, 45mg, 50mg, 55mg, 60mg, 65mg, 70mg, 75mg, 80mg, 85mg, 90mg, 95mg, 100mg, 125mg, 150mg 175mg, 200mg, 225mg, 250mg, 275mg, 300mg, 325mg, 350mg, 375mg, 400mg, 425mg, 450mg, 475mg and 500mg are examples.

In an embodiment, there is provided a pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) and one or more of: (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4), (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-3, 6-dione (5), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] hept-3-one (6), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) or (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid methyl ester (9).

In an embodiment, there is provided a pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (1) and one or more of: cyclopent-3-ene-carboxylic acid ethyl ester (10), (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11), (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylic acid ethyl ester (12), (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13), (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14) or (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid ethyl ester (15) .

In embodiments, (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid can be provided as an acid addition salt, a zwitterion hydrate, a zwitterion anhydrate, a hydrochloride or hydrobromide salt, or as a zwitterion monohydrate. Acid addition salts include, but are not limited to, addition salts of maleic acid, fumaric acid, benzoic acid, ascorbic acid, succinic acid, oxalic acid, bismethylenesalicylic acid, methanesulfonic acid, ethanedisulfonic acid, acetic acid, propionic acid, tartaric acid, salicylic acid, citric acid, gluconic acid, lactic acid, malic acid, mandelic acid, cinnamic acid, citraconic acid, aspartic acid, stearic acid, palmitic acid, itaconic acid, glycolic acid, pantothenic acid, p-aminobenzoic acid, glutamic acid, benzenesulfonic acid, or theophylline acetic acid, and 8-halotheophyllines, such as 8-bromo-theophylline. In embodiments, addition salts of inorganic acids may be used, including, but not limited to, addition salts of hydrochloric, hydrobromic, hydroiodic, sulfuric, sulfamic, phosphoric, or nitric acids.

In embodiments, (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3), (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4), (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-3, 6-dione (5), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] hept-3-one (6), Methyl (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7), (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) or (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) may be provided as an acid addition salt, a zwitterionic hydrate, a zwitterionic anhydride, a hydrochloride or hydrobromide salt or in the form of a zwitterionic monohydrate. Acid addition salts include, but are not limited to, addition salts of maleic acid, fumaric acid, benzoic acid, ascorbic acid, succinic acid, oxalic acid, bismethylenesalicylic acid, methanesulfonic acid, ethanedisulfonic acid, acetic acid, propionic acid, tartaric acid, salicylic acid, citric acid, gluconic acid, lactic acid, malic acid, mandelic acid, cinnamic acid, citraconic acid, aspartic acid, stearic acid, palmitic acid, itaconic acid, glycolic acid, pantothenic acid, p-aminobenzoic acid, glutamic acid, benzenesulfonic acid, or theophylline acetic acid, and 8-halotheophyllines, such as 8-bromo-theophylline. In embodiments, addition salts of inorganic acids may be used, including, but not limited to, addition salts of hydrochloric, hydrobromic, hydroiodic, sulfuric, sulfamic, phosphoric, or nitric acids.

In embodiments, cyclopent-3-ene-carboxylic acid ethyl ester (10), (3R,4S) -3- ((tert-butoxycarbonyl) amino) -4- (hydroxy) cyclopentanecarboxylic acid ethyl ester (11), (3R) -3- ((tert-butoxycarbonyl) amino) -4-oxo-cyclopentanecarboxylic acid ethyl ester (12), (9S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonanecarboxylic acid ethyl ester (13), (S) -9- (tert-butoxycarbonylamino) -1, 4-dioxa-7-spiro [4.4] nonene-7-carboxylic acid ethyl ester (14), or (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1- Ethyl formate (15) may be provided as an acid addition salt, a zwitterionic hydrate, a zwitterionic anhydride, a hydrochloride or hydrobromide salt or in the form of a zwitterionic monohydrate. Acid addition salts include, but are not limited to, addition salts of maleic acid, fumaric acid, benzoic acid, ascorbic acid, succinic acid, oxalic acid, bismethylenesalicylic acid, methanesulfonic acid, ethanedisulfonic acid, acetic acid, propionic acid, tartaric acid, salicylic acid, citric acid, gluconic acid, lactic acid, malic acid, mandelic acid, cinnamic acid, citraconic acid, aspartic acid, stearic acid, palmitic acid, itaconic acid, glycolic acid, pantothenic acid, p-aminobenzoic acid, glutamic acid, benzenesulfonic acid, or theophylline acetic acid, and 8-halotheophyllines, such as 8-bromo-theophylline. In embodiments, addition salts of inorganic acids may be used, including, but not limited to, addition salts of hydrochloric, hydrobromic, hydroiodic, sulfuric, sulfamic, phosphoric, or nitric acids.

In embodiments, the pharmaceutical composition includes a variety of dosage forms, including conventional formulations and modified release formulations. Such pharmaceutical compositions may be adapted for any suitable route of administration, such as oral, rectal, nasal, ocular, pulmonary, vaginal, sublingual, transdermal, intravenous, intraarterial, intramuscular, intraperitoneal and subcutaneous routes. Suitable dosage forms include tablets, capsules, oral liquids, eye drops, ophthalmic ointments, ophthalmic gels, powders, aerosols, transdermal forms such as topical liquids, patches, creams and ointments, parenteral formulations and suppositories.

In embodiments, as previously mentioned, the pharmaceutical compositions herein may be provided in a conventional release profile or a modified release profile. Pharmaceutical compositions can be prepared using pharmaceutically acceptable "carriers" that contain materials that are considered safe and effective. "carriers" include all components present in a pharmaceutical preparation which are different from one or more active ingredients (active ingredients or ingredients). The term "carrier" includes, but is not limited to, diluents, binders, lubricants, disintegrants, fillers (filler), and coating compositions. Those skilled in the art are familiar with such pharmaceutical carriers and with methods of formulating (compounding) pharmaceutical compositions using such carriers.

In embodiments, the pharmaceutical compositions herein are modified release dosage forms that provide a modified release profile. The modified release profile may exhibit an immediate release profile, a delayed release profile, or an extended release profile. Conventional (or unmodified) release oral dosage forms such as tablets, capsules, suppositories, syrups, solutions and suspensions generally release the drug into the mouth, stomach or intestine as the tablet, capsule shell or suppository dissolves, or in the case of syrups, solutions and suspensions, when they are swallowed. The pattern of drug release from Modified Release (MR) dosage forms is intentionally varied from that of conventional dosage forms to achieve desired therapeutic goals and/or better patient compliance. Types of MR drug products include Orally Disintegrating Dosage Forms (ODDF) providing immediate release, extended release dosage forms, delayed release dosage forms (e.g., enteric coated), and pulsatile release dosage forms.

ODDF is a solid dosage form containing a pharmaceutical substance or active ingredient that typically disintegrates rapidly within a few seconds when placed on the tongue. The disintegration time of ODDF is typically in the range of from one or two seconds to about one minute. ODDF is designed to disintegrate or dissolve rapidly upon contact with saliva. This mode of administration may be beneficial to persons who may have the problem of swallowing tablets, whether the problem is due to physical weakness or mental illness in nature. Some subjects with eye disorders may exhibit such behavior. ODDF can provide rapid delivery of a drug to the bloodstream through the mucosa, resulting in a rapid onset of action. Examples of ODDFs include orally disintegrating tablets, capsules, and fast dissolving films and sheets.

Extended Release Dosage Forms (ERDF) have an extended release profile and are those that allow for a reduction in the frequency of administration compared to the frequency of administration exhibited by conventional dosage forms, such as solutions or unmodified release dosage forms. ERDF provides a sustained duration of drug action. Suitable formulations providing extended release profiles are well known in the art. For example, coated slow release beads or granules ("beads" and "granules" are used interchangeably herein), wherein any of the compounds described herein are applied to beads, e.g., capsules nonpareil beads, and then coated with a conventional release-retarding material such as wax, enteric coating, and the like. In embodiments, beads may be formed in which any of the compounds described herein are mixed with a material to provide a mass from which the compound is leached. In embodiments, the beads may be engineered to provide different release rates by varying the characteristics of the coating or the mass, such as thickness, porosity, using different materials, and the like. Beads having different release rates can be combined into a single dosage form to provide variable or continuous release. The beads may be contained in a capsule, or compressed into a tablet.

In embodiments, the modified dosage forms herein include delayed release dosage forms having a delayed release profile. The delayed release dosage form may comprise a delayed release tablet or a delayed release capsule. A delayed release tablet is a solid dosage form that releases a compound (or compounds) described herein at a time other than immediate release after administration. Delayed release capsules are solid dosage forms in which the drug is enclosed in a hard or soft soluble container made of a suitable form of gelatin and which release the drug(s) at a time other than immediate release after administration. For example, enteric coated tablets, capsules, granules and beads are well known examples of delayed release dosage forms. Enteric coated tablets, capsules and granules and beads pass through the stomach and release the drug in the intestine. In embodiments, the delayed release tablet is a solid dosage form comprising agglomerates of pharmaceutical particles that release a drug (or drugs) at a time other than immediate release following administration. In embodiments, the agglomerates of the pharmaceutical particles are covered with a coating that delays drug release. In embodiments, the delayed release capsule is a solid dosage form comprising an agglomeration of pharmaceutical particles that release a drug (or drugs) at a time other than immediate release following administration. In embodiments, the agglomerates of the pharmaceutical particles are covered with a coating that delays drug release.

Delayed release dosage forms are known to those skilled in the art. For example, coated delayed release beads or granules, wherein any of the compounds described herein are applied to the beads, for example, conditioners nonpareil beads, and then coated with a conventional release delaying material such as wax, enteric coating, and the like. In embodiments, can be in the form ofBeading, wherein any of the compounds described herein are mixed with a material to provide a mass from which the drug is leached. In embodiments, the beads may be engineered to provide different release rates by varying the characteristics of the coating or the mass, such as thickness, porosity, using different materials, and the like. In embodiments, an enteric-coated granule of any of the compounds described herein may be contained in an enteric-coated capsule or tablet that releases the granule in the small intestine. In embodiments, the granules have a coating that remains intact until the coated granules reach at least the ileum, and thereafter provide delayed release of the drug in the colon. Suitable enteric coating materials are well known in the art and may be, for example,coatings such as methacrylic acid and methyl methacrylate polymers, and others. The granules may be contained in capsules or compressed into tablets.

In embodiments, any of the compounds described herein are incorporated into a porous inert carrier that provides a delayed release profile. In embodiments, the porous inert carrier comprises channels or passageways from which the drug diffuses into the surrounding fluid. In embodiments, any of the compounds described herein are incorporated into an ion exchange resin to provide a delayed release profile. The predetermined release rate of the drug from the resin may result in a delayed action when the drug-resin complex contacts gastrointestinal fluids and ionic components dissolved therein. In embodiments, the membrane is used to control the rate of release from a reservoir containing a drug. In embodiments, the liquid product may also be used to provide a delayed release profile. For example, liquid articles consisting of solid particles dispersed throughout a liquid phase in which the particles are insoluble. The suspension is formulated to allow at least a reduction in the frequency of administration compared to the frequency of administration exhibited by the drug as a conventional dosage form (e.g., as a solution or conventional solid dosage form of immediate release drug). For example, a suspension of ion exchange resin components or beads.

In embodiments, the pharmaceutical compositions described herein are suitable for ocular administration or parenteral administration, including, for example, intramuscular (i.m.), intravenous (i.v.), subcutaneous (s.c.), intraperitoneal (i.p.), or intrathecal (i.t). Parenteral or ophthalmic compositions must be sterile for administration by injection, infusion, instillation or implantation into the body, and may be packaged in single-dose or multi-dose containers. In embodiments, the liquid pharmaceutical composition for ocular or parenteral administration to a subject comprises an active substance, e.g., any compound described herein in any of the respective amounts described above. In embodiments, the pharmaceutical composition for ocular or parenteral administration is formulated in a total volume of about, e.g., 1ml, 2ml, 3ml, 4ml, 5ml, 7.5ml, 10ml, 20ml, 25ml, 50ml, 100ml, 200ml, 250ml, or 500 ml. In embodiments, the composition is contained in a bag, glass vial, plastic vial, or bottle.

In embodiments, the pharmaceutical composition for ocular or parenteral administration comprises the respective amounts described above for any of the compounds described herein. In embodiments, a pharmaceutical composition for ocular or parenteral administration comprises from about 0.0001mg to about 500mg of any compound described herein. In embodiments, a pharmaceutical composition for ocular or parenteral administration to a subject may comprise any of the compounds described herein at a corresponding concentration of about 0.005mg/ml to about 500 mg/ml. In embodiments, a pharmaceutical composition for ocular or parenteral administration comprises any of the compounds described herein at a corresponding concentration of, for example, about 0.05mg/ml to about 50mg/ml, about 0.1mg/ml to about 10mg/ml, about 0.05mg/ml to about 25mg/ml, about 0.05mg/ml to about 10mg/ml, about 0.05mg/ml to about 5mg/ml, or about 0.05mg/ml to about 1 mg/ml. In embodiments, a pharmaceutical composition for ocular or parenteral administration comprises any of the compounds described herein at a corresponding concentration of, for example, about 0.05mg/ml to about 15mg/ml, about 0.5mg/ml to about 10mg/ml, about 0.25mg/ml to about 5mg/ml, about 0.5mg/ml to about 7mg/ml, about 1mg/ml to about 10mg/ml, about 5mg/ml to about 10mg/ml, or about 5mg/ml to about 15 mg/ml.

In an embodiment, a pharmaceutical composition for ocular or parenteral administration is provided, wherein the pharmaceutical composition is stable for at least six months. In embodiments, the pharmaceutical composition for ocular or parenteral administration exhibits a reduction of no more than about 5% of the active agent, e.g., (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof, over, e.g., 3 months or 6 months. In embodiments, the amount of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof degrades by no more than about, e.g., 2.5%, 1%, 0.5%, or 0.1%. In embodiments, the degradation is less than about, e.g., 5%, 2.5%, 1%, 0.5%, 0.25%, 0.1% for at least six months.

In an embodiment, a pharmaceutical composition for ocular or parenteral administration is provided, wherein the pharmaceutical composition remains soluble. In embodiments, pharmaceutical compositions for ocular or parenteral administration are provided that are stable, soluble, locally site compatible and/or ready to use (ready-to-use). In embodiments, the pharmaceutical compositions herein are ready-to-use for direct administration to a subject in need thereof.

Pharmaceutical compositions provided herein for ocular or parenteral administration may comprise one or more excipients, such as solvents, solubility enhancers, suspending agents, buffers, isotonic agents, stabilizers, or antimicrobial preservatives. When used, the excipients of the ophthalmic or parenteral compositions will not adversely affect the stability, bioavailability, safety and/or efficacy of any of the compounds described herein used in the compositions. Thus, ophthalmic or parenteral compositions are provided in which there is no incompatibility between any of the components of the dosage form.

In embodiments, an ophthalmic composition or parenteral composition comprising any of the compounds described herein comprises a stabilizing amount of at least one excipient. For example, the excipient may be selected from the group consisting of: buffers, solubilizers, tonicity agents, antioxidants, chelating agents, antimicrobial agents and preservatives. It will be appreciated by those skilled in the art that excipients may have more than one function and be classified into one or more defined groups.

In embodiments, the ophthalmic composition or parenteral composition comprises any compound described herein and an excipient, wherein the excipient is present at a weight percentage (w/v) of less than about, e.g., 10%, 5%, 2.5%, 1%, or 0.5%. In embodiments, the excipient is present at a weight percentage of between about, e.g., 1.0% to 10%, 10% to 25%, 15% to 35%, 0.5% to 5%, 0.001% to 1%, 0.01% to 1%, 0.1% to 1%, or 0.5% to 1%. In embodiments, the excipient is present at a weight percentage of between about, e.g., 0.001% to 1%, 0.01% to 1%, 1.0% to 5%, 10% to 15%, or 1% to 15%.

In an embodiment, provided is an ophthalmic composition or parenteral composition of any of the compounds described herein, wherein the pH of the composition is between about 4.0 to about 8.0. In embodiments, the pH of the composition is between, for example, about 5.0 to about 8.0, about 6.0 to about 8.0, about 6.5 to about 8.0. In embodiments, the pH of the composition is between, for example, about 6.5 to about 7.5, about 7.0 to about 7.8, about 7.2 to about 7.8, or about 7.3 to about 7.6. In embodiments, the pH of the aqueous solution is, for example, about 6.8, about 7.0, about 7.2, about 7.4, about 7.6, about 7.7, about 7.8, about 8.0, about 8.2, about 8.4, or about 8.6.

In embodiments, a pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof provides (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid having a C of less than about, e.g., 2000ng/ml, 1000ng/ml, 850ng/ml, 800ng/ml, 750ng/ml, 700ng/ml, 650ng/ml, 600ng/ml, 550ng/ml, 450ng/ml, 400ng/ml, 350ng/ml, or 300ng/ml_{Maximum of}In vivo plasma profile of (a). In embodiments, the pharmaceutical composition provides a C having less than about, e.g., 250ng/ml, 200ng/ml, 150ng/ml, or 100ng/ml_{Maximum of}In vivo plasma profile of (a).

In an embodiment of the present invention, the substrate is,provided herein are pharmaceutical compositions comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof and one or more of any of the compounds described herein, wherein the composition provides an AUC of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid having less than about 900 ng-hr/ml_0-∞Constant in vivo plasma profile of (a).

In an embodiment, T of a pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof and one or more of any of the compounds described herein_{Maximum of}Less than 3 hours. In an embodiment, T of the pharmaceutical composition_{Maximum of}Less than 2.5 hours. In an embodiment, T of the pharmaceutical composition_{Maximum of}Less than 2 hours. In an embodiment, T of the pharmaceutical composition_{Maximum of}Less than 1.5 hours. In an embodiment, T of the pharmaceutical composition_{Maximum of}Less than 1 hour. In an embodiment, T of the pharmaceutical composition_{Maximum of}Less than 0.5 hour. In an embodiment, T of the pharmaceutical composition_{Maximum of}Less than 0.25 hours.

In embodiments, a pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof and one or more of any of the compounds described herein provides a dissolution rate of at least about 80% within the first 20 minutes of administration to a subject in need thereof. In embodiments, a pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof and one or more of any of the compounds described herein provides a dissolution rate of at least about, e.g., 85%, 90%, or 95% within the first 20 minutes of administration to a subject in need thereof. In an embodiment, a pharmaceutical composition comprising (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof and one or more of any of the compounds described herein provides a dissolution rate of at least 80% within the first 10 minutes of administration to a subject in need thereof.

It is to be understood that the corresponding amounts of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof and one or more of any compound described herein are suitable for all dosage forms described herein, including conventional dosage forms, modified dosage forms, and ophthalmic and parenteral formulations described herein. One skilled in the art will determine an appropriate amount based on criteria such as dosage form, route of administration, subject tolerance, efficacy, therapeutic goal and therapeutic benefit, and other pharmaceutically acceptable criteria.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.

The terms "about" or "about" as used herein mean within an acceptable error range for the particular value as determined by one of ordinary skill in the art, which will depend in part on how the value is measured or determined, i.e., the limiting factor (limitation) of the measurement system. For example, "about" can mean within 3 or more than 3 standard deviations, according to practice in the art. Alternatively, "about" may mean a range of up to 20%, up to 10%, up to 5%, and/or up to 1% of a given value. Alternatively, particularly with respect to biological systems or processes, the term may mean within an order of magnitude of the value, preferably within 5 times the value, and more preferably within 2 times the value.

"PK" refers to the pharmacokinetic profile. C_{Maximum of}Is defined as the highest plasma drug concentration (ng/ml) estimated during the experiment. T is_{Maximum of}Is defined as when C_{Maximum of}Time when estimated (min). AUC_0-∞Is the total area under the plasma drug concentration-time curve (ng hr/ml) from drug administration until drug is eliminated. The area under the curve is determined by the clearance. Clearance is defined as the volume of blood or plasma (ml/min) per unit time that is completely cleared of its drug content.

"pharmaceutically acceptable" refers to molecular entities and compositions that are "generally considered safe", e.g., that are physiologically tolerable and do not typically produce allergic or similar untoward reactions such as gastric upset and the like when administered to a human. In embodiments, the term refers to molecular entities and compositions approved by a regulatory agency of the Federal or a state government, as a GRAS list or similar list under sections 204(s) and 409 of the Federal Food, Drug and Cosmetic Act (Federal Food, Drug and Cosmetic Act) that has undergone pre-market review and approval by the FDA, the U.S. pharmacopeia, or another generally recognized pharmacopeia for use in animals, and more particularly in humans.

By "effective amount" or "therapeutically effective amount" is meant a dose sufficient to alleviate one or more symptoms of the disorder, disease or condition being treated.

"co-administration with.... co-administration", "co-therapy", "combination with.... a.. combination", "combination with.. a.. or" administration with.. a.. may be used interchangeably and means that two or more agents are administered during the course of therapy. These agents may be administered together at the same time or separately at spaced intervals. These agents may be administered in a single dosage form or in separate dosage forms.

"patient in need thereof" includes individuals who have been diagnosed as having a disease, condition or disorder, and is indicated for treatment with (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid or a pharmaceutically acceptable salt thereof. "patient" and "subject" are used interchangeably herein.

Examples

The examples provided herein are included merely to supplement the disclosure herein and should not be considered limiting in any respect.

General procedure

(1R,4S) -2-azabicyclo [2.2.1]Hept-5-en-3-one (2) was purchased from Acella Chembiol, San Diego, CA 92121 or AK Scientific, Inc., Union City, CA 94587. 4-methoxybenzyl chloride was purchased from AK Scientific, Inc., Union City, CA 94587. 2- (difluoromethyl) sulfinyl) pyridine (20) was purchased from amine Chemicals, Monmouth Jct., NJ 08852, Sigma-Aldrich Corp, St Louis, MO or synthesized from diethyl bromodifluoromethylphosphonate and 2-mercaptopyridine. See, Zhou, q.; ruffoni, a.; giantassio, r.; fujiwara, y.;sella, e.; shabat, d.; baran, p.s.angelw.chem.int.ed.2013, 52, 3949-. 1, 3-dibromo-5, 5-dimethylhydantoin was purchased from Acros Organics division of Thermo Fisher Scientific, Waltham, MA 02451. TPAP is available from Combi Blocks, Inc. san Diego, CA 92126. Cerium ammonium nitrate was purchased from Alfa Aesar, Ward Hill, MA 01835. All other reagents were purchased from Sigma-Aldrich, Fisher Scientific or Acros Organics and used without further purification. Anhydrous solvents (THF, CH)₂Cl₂DMF) was purified by passage through a column containing activated alumina and a supported copper redox catalyst prior to use. Yield refers to chromatography and spectrum: (¹H-NMR) homogeneous material. Analytical Thin Layer Chromatography (TLC) Merck silica gelF-254 was performed on pre-coated plates (0.25mm thick) and the components were visualized by UV light (254nm) and/or cerium ammonium molybdate staining. Flash column chromatography with multiple Teledyne cassettes (4g-80g, 40 μm-63 μm,) The Teledyne Commiflash Rf Plus automated Rapid purification System. Unless otherwise stated, purification was performed with hexane and ethyl acetate.¹H NMR and¹³c NMR Spectroscopy on a Bruker Avance-III NMR spectrometer in CDCl₃Or D₂Recorded in O at 500MHz and 126MHz respectively. Chemical shifts are reported in ppm, and multiplicities are indicated by: s is singlet, d is doublet, t is triplet, q is quartet, sep is heptamer, dd is doublet, dt is triplet doublet, m is multiplet, br is broad resonance. Coupling constants are reported in Hz. High resolution mass spectral data were obtained using electrospray ionization in positive ion mode on an Agilent 6210LC-TOF spectrometer with an Agilent G1312A HPLC pump and an Agilent G1367B auto-injector, Integrated Molecular Structure and Research Center (IMSERC), Northwestern University. Analytical HPLC was performed by using reverse phase Agilent Infinity 1260HPLC with Phenomenex Kintex C-18 column (50X 2.1mm, 2.6 μm) with detection of UV absorbance at 254nm。

Example 1

Preparation of (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hept-5-en-3-one (3)

Method A

4-Methoxybenzyl alcohol (35.80mL, 0.29mol, 1.5 eq.) was added dropwise to concentrated HCl (300mL) and stirring was continued for 1 h. Water was added and the liquid was extracted with ether (2X 100 mL). Passing diethyl ether over Na₂SO₄Dried, and concentrated to a volume of about 50 mL. To a 2L flask equipped with an addition funnel was added (1R,4S) -2-azabicyclo [2.2.1]Hept-5-en-3-one (21.00g, 0.19mol), DMF (600mL) and THF (600mL) and the flask was cooled to 0 ℃. NaH (8.45g, 0.21mol, 1.1 equiv., 60% dispersion in mineral oil) was added in portions. The flask was placed in N₂Next, and stirring was continued for 30 min. Adding Et₂The O/PMBCl solution was transferred to the addition funnel and added dropwise at 0 ℃. The reaction was stirred at room temperature for 6 h. Upon completion, THF was removed in vacuo and diethyl ether and water were added. Any solids were filtered and the layers were separated. The aqueous layer was extracted with ether (3X 100mL), and the organic layers were combined and washed with brine (2X 200 mL). In the presence of Na₂SO₄After drying and concentration, a yellow oil was obtained. The crude oil was purified by flash chromatography to give 32.2g (0.14mol, 73% yield) of protected (1R,4S) -2-azabicyclo [2.2.1]]Hept-5-en-3-one (3). The spectra match those in the literature. See Qiu, j.; silverman, R.B.J.Med.chem.2000,43, 706-.

Method B

A dry 2 liter 3-neck round-bottom flask was equipped with an overhead stirrerPaddle, 500ml dropping funnel and serum cap/type K thermocouple/N₂And (3) a needle. Reacting (1R,4S) - (-) -2-aza-bicyclo [2.2.1]Hept-5-en-3-one (25g, 229mmol, 1 eq.) was dissolved in anhydrous THF (600ml) in a flask and the dropping funnel was loaded with a solution of LiHMDS (1M solution in toluene). The flask contents were cooled to-40 ℃ and a solution of LiHMDS (252ml, 252mmol, 1.2 equivalents) was added dropwise to the flask, maintaining the temperature at about-35 ℃To 40 ℃. The flask contents began to thicken and became a thin gel at the end of the base addition. After the LiHMDS had been added in its entirety, the reaction mixture was stirred for another 1 hour, and then the 500ml dropping funnel was removed and replaced with a smaller 125ml dropping funnel loaded with 4-methoxybenzyl chloride (37.2g, 240.5mmol, 1.05 equivalents). The halide was added dropwise to the reaction flask. When about 1/4 chloride had been added, tetrabutylammonium iodide powder (1.3g, 3.44mmol, 0.015 eq.) was added in one portion. When all 4-methoxybenzyl chloride was added, the flask was initially warmed to room temperature and then to 60 ℃ in a heating mantle. The progress of the benzylation reaction was followed by HPLC and LCMS over time. After 2 days at 60 ℃ when the reaction has reached the lactam (-) (1R,4S) -2-azabicyclo [2.2.1](ii) treatment reaction at a conversion of hept-5-en-3-one (3) of-85%. The reaction solution was freed of fine solid precipitate by filtration through a 17cm large buchner funnel/filter paper under vacuum. The residue was washed with THF (200ml) and the original filtrate was also collected and the combined golden yellow filtrates were concentrated (rotary evaporator/vacuum/water bath at 40 ℃). The residual gold oil was dissolved in EtOAc (350mL) and washed with water (250 mL). After phase separation, the aqueous layer was back-extracted with EtOAc (2X 100 mL). The EtOAc layers were combined and passed over anhydrous Na₂SO₄The powder was dried, filtered and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to a golden yellow liquid. The crude product was purified on a Biotage using a 340g silica column and EtOAc-hexane gradient [ 15% (2CV) 15% -75% (8CV) 100% (3CV)]Purification by chromatography, wherein fractions were collected in 25X 150mm tubes. The fractions containing the product were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) into a golden yellow liquid which was pumped on a vacuum line for several hours.

Method C

NaH (40.3g, 1.01mol, 60% purity, 1.1 equiv.) and Bu were combined₄NI (16.9g, 45.8mmol, 0.05 eq.) was added to THF (300mL) and (1R,4S) -2-azabicyclo [2.2.1] was added]A solution of hept-5-en-3-one (100.0g, 916.3mmol, 1 eq.) in DMF (900mL) was added dropwise to the mixture at 0 ℃. Mixing the raw materialsStirring was continued for 0.5h and p-methoxybenzyl chloride (215.2g, 1.37mol, 186.5mL, 1.50 equiv.) was added dropwise to the above mixture at 0 ℃. The mixture was stirred at 25 ℃ for 1 h. TLC (petroleum ether: ethyl acetate: 1, R)_f0.20) showed complete consumption of the reactants. The mixture was diluted with MTBE (2L) and water (3.5L) was added. Any solids were filtered and the layers were separated. The aqueous layer was extracted with MTBE (800 mL. times.2), and the organic layers were combined and washed with brine (1L. times.2). The combined organic layers were passed over anhydrous Na₂SO₄Dried and concentrated to give a residue as a yellow oil. The residue was purified by column chromatography on silica gel with petroleum ether: ethyl acetate (10:1 to 1:1) was purified to give a yellow oil. Crude (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] as a yellow oil was obtained]Hept-5-en-3-one (3) (89.5g, 390.3mmol, 42.6% yield), which was used in the next step without further purification.

Example 2

Preparation of (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] hept-6-yl acetate (4)

Method A

To (1R,4S) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]A solution of hept-5-en-3-one (3) (10.00g, 43.62mmol) in AcOH (110.0mL) was added 1, 3-dibromo-5, 5-dimethylhydantoin (7.48g, 26.17mmol, 0.6 equiv.). The reaction was stirred for 6h and, upon completion, water was added. The aqueous layer was extracted with ether (3X 200mL) and the organic layers were combined, washed with 1M NaOH, and Na₂SO₄Dried and concentrated. Purification by flash chromatography yielded (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] as thick oil]Hept-6-yl acetate (4) (14.40g, 39.25mmol, 90% yield). The spectra match those in the literature. See Qiu, j.; silverman, R.B.J.Med.chem.2000,43, 706-.

Method B

Mixing (1R,4R) - (-) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Hept-5-en-3-one (15.5g, 67.60mmol, 1 eq.) was dissolved in glacial acetic acid (125ml) in a 250ml round bottom flask with a stir bar. At room temperature1, 3-dibromo-5, 5-dimethylhydantoin (9.7g, 33.43mmol, 0.5 equiv.) was added to the acidic solution in multiple batches over 10 minutes. A serum cap/nitrogen needle was placed in the neck of the flask and the reaction mixture was stirred at room temperature overnight. Within 20 minutes, the initially turbid yellow solution became clear, golden yellow after all dibromide was added. The progress of the reaction was monitored by HPLC and LCMS. After stirring overnight, the reaction solvent was removed (rotary evaporator/vacuum/water bath at 55 ℃) to provide a deep golden yellow liquid which was then dissolved in dichloromethane (200 ml). Water (100ml) was added, and the mixture was transferred to a 1L Erlenmeyer flask. A 10% sodium sulfite solution (75ml) was added and stirred vigorously in an erlenmeyer flask (pharmaceutical flash) for 1/2 hours to destroy unreacted dibromohydantoin. More water (100ml) was added and then 3M sodium hydroxide was added slowly and swirled rapidly in an erlenmeyer flask to bring the aqueous layer to pH 7(pH paper). The flask contents were transferred to a 1L separatory funnel; the Erlenmeyer flask was rinsed with dichloromethane (100ml) and the rinses were combined in a funnel. The dichloromethane layer from the phase separation was saved, the aqueous layer was back-extracted with dichloromethane (2X 100ml) and combined with the initially saved extract with saturated NaHCO₃(250ml), water (250ml) and brine (250 ml). Anhydrous Na for organic phase₂SO₄The powder was dried, filtered and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to a golden yellow liquid. The crude product was purified on a Biotage using a 340g silica column and EtOAc-hexane gradient [ 15% (1CV) 15% -75% (7.5CV) 100% (3CV) ]]Purification by chromatography and fractions were collected in 25X 150mm tubes. The product-containing fractions were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to give a golden yellow liquid which was further pumped on a vacuum line for several hours, yielding purified (lR,4R,6S,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1]-hept-6-yl acetate (4) (23 g; 82%).

Example 3

Preparation of (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5)

Method A

Reacting (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1]Hept-6-ylacetate (4) (12.8g, 34.7mmol) was dissolved in MeOH (270mL) and K was added₂CO₃(14.40g, 104.28mmol, 3.0 equiv.). The reaction was stirred for 1h, filtered and then concentrated. Ethyl acetate and water were added and the layers were separated. The organic layer was washed with Na₂SO₄Dried and concentrated to give ((1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [ 2.2.1) as an off-white solid]Hept-3-one) (25), which was used directly in the next step.

The compound was placed in a 500mL flask and purged with argon. Dichloromethane (170mL) was added followed by dichloromethaneMolecular sieves (10 g). TPAP (122.2mg, 0.35mmol, 0.01 equiv.) and NMO (8.14g, 69.52mmol, 2.0 equiv.) were then added and the reaction mixture was stirred overnight. The reaction mixture was then filtered and concentrated to a volume of 20mL and loaded directly onto a flash chromatography column. The resulting yellow solid can be recrystallized from hexane/ethyl acetate to obtain (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] as a white powder]Hepta-3, 6-dione (5) (5.96g, 18.38mmol, 52% yield). The spectra match those in the literature. See Qiu, j.; silverman, R.B.J.Med.chem.2000,43, 706-.

Method B

Reacting (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1]Hept-6-ylacetate (4) (25.5g, 69.2mmol) was dissolved in MeOH (300mL) and K was added₂CO₃(30g, 0.23mol, 3 equivalents). The reaction was stirred for 1h, filtered and then concentrated. Ethyl acetate and water were added and the layers were separated. The organic layer was washed with Na₂SO₄Dried and concentrated to give ((1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [ 2.2.1) as an off-white solid]Hept-3-one), which was used directly in the next step. The three-necked flask was equipped with a vent line to the gas bubble, dropping with nitrogen inletA funnel and a septum. Dichloromethane (160mL) was added and the flask was purged with nitrogen. Oxalyl chloride (8.40mL, 98.0mmol, 1.4 equiv.) was added and the reaction cooled to-78 ℃. DMSO (11.60mL, 0.16mol, 2.3 equivalents) was added to the addition funnel and then slowly added dropwise at a rate that controlled vigorous gas evolution (evolution). After addition, the reaction was stirred at-78 ℃ for 10 min. The deacylated material was dissolved in dichloromethane (160mL) and added slowly to the reaction via an addition funnel. The reaction was stirred at-78 ℃ for 10 min. Triethylamine (68.3mL, 0.49mol, 7 equivalents) was then added dropwise via the addition funnel. Upon completion, the reaction was stirred at-78 ℃ for 10min, warmed to room temperature, and quenched with 1M HCl. After separation, the organic layer was passed over Na₂SO₄Dried and concentrated in a fume hood. Purification via flash chromatography yielded (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] as a beige solid]Hepta-3, 6-dione (5) (13.5g, 41.7mmol, 60% yield).

Method C

To (1R,4R,6S,7R) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo [2.2.1] in MeOH (680mL)]Hept-6-ylacetate (4) (96.5g, 262.0mmol, 1 eq.) was added K₂CO₃(108.6g, 786.2mmol, 3 equiv.). The mixture was stirred at 25 ℃ for 1 h. TLC (petroleum ether: ethyl acetate: 1, R)_f0.65) showed the reaction was complete. The mixture was filtered and the filtrate was concentrated under reduced pressure to give a dark brown solid. MTBE (500mL) was added to the brown solid and the mixture was stirred for 3h, then filtered to give a filtrate which was concentrated under reduced pressure to give the crude product. The crude compound was obtained as an off-white solid (76.5g, 234.5mmol, 89.5% yield), which was used in the next step without further purification.

The above crude compound (76.5g, 234.5mmol, 1 eq) was added to MeCN (400 mL). IBX (65.6g, 234.5mmol, 1.0 equiv.) was added to the above mixture in one portion at 20 deg.C-30 deg.C for 0.5 h. The reaction mixture was stirred at 75-80 ℃ for 2h, after which time TLC (petroleum ether: ethyl acetate ═ 3:1, R)_f0.23) showed completion of the reaction. The mixture was concentrated under reduced pressure to give the crude product, which was purified by column chromatography on silica gel with petroleum ether: ethyl acetate (20: 1-1: 1) purification to give (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] as an off-white solid]Hepta-3, 6-dione (5) (48.5g, 149.6mmol, 63.7% yield).

Example 3(a)

Preparation of (1R,4R,6S,7R) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (25)

Mixing (1R,4R,6S,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -3-oxo-2-azabicyclo- [2.2.1]-hept-6-yl acetate (4) (22.25g, 60.42mmol, 1 eq.) was dissolved in a solvent mixture of methanol (120mL) and water (15mL) in a 500mL round bottom flask. Potassium carbonate powder (12.5g, 90.45mmol, 1.5 equiv.) was added to the golden yellow solution and the resulting cloudy reaction mixture was capped with serum/N₂The needle was sealed and stirred at room temperature overnight. The progress of the reaction was monitored by LCMS and HPLC. The reaction was worked up by evaporating the volatiles (rotary evaporator/vacuum/water bath at 40 ℃). Distilled water (200ml) was added to the dark golden yellow oil obtained from evaporation. The pH of the aqueous layer was adjusted to pH 7 with 1M hydrochloric acid and the product was extracted into dichloromethane (200ml, then 2 × 150 ml). The dichloromethane extracts were combined and washed with water (200ml), brine (250ml), Na₂SO₄And (5) drying the powder. The dried extracts were filtered and the spent desiccant was rinsed with dichloromethane (2 × 50ml) and the combined extracts were concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to a golden yellow oil. The golden yellow product was divided into two approximately equal portions and each portion was purified on a 100g silica column on Biotage using an EtOAc-hexanes gradient [ 20% (1CV) 20% -100% (7CV) 100% (5CV)]Purification by chromatography and fractions were collected in 25X 150mm tubes. The product fractions were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to a golden yellow liquid which was pumped on a vacuum line for several hours. Two chromatographically purified samples (20g) were combined and crystallized from hexane-EtOAc. The first batch of crystals (17g) was collected. Mixing the mother liquorConcentrated and crystallized from hexane-EtOAc to provide a second crop of crystals (2 g). (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-aza-bicyclo [2.2.1] is obtained as a white crystalline powder]Hept-3-one (25) (15 g total; 75%).

Example 3(b)

Preparation of (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) by Swern oxidation

Will be equipped with an overhead stirrer, a 50ml dropping funnel and a serum cap/thermocouple/N₂A1 liter 3-necked round bottom flask of needles was loaded with a solution of oxalyl chloride (3.4g (2.3ml), 1.25 equivalents) and methylene chloride (90ml) and the stirred acidic chloride solution was placed in acetone/CO₂Cooling to-60 ℃ in a cooling bath. The dropping funnel was loaded with a solution of DMSO (2.6g (2.35ml), 1.5 equivalents) in dichloromethane (18ml) and this solution was added to the cold acidic chloride solution over 3 minutes. The resulting mixture was stirred at-60 ℃ for 7 minutes and then (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] was added to the solution over 10 minutes]-hept-3-one (25) (7.2g, 22.1mmol, 1 equiv.). The reaction mixture was kept at-60 ℃ for 25 minutes, and then pure trimethylamine (21.5ml, 7 equivalents) was placed in the dropping funnel and added to the flask. The resulting milky white solution was kept cold for 1 hour, the reaction was checked by HPLC/LCMS, and then allowed to warm to room temperature within 2.5 hours before treatment. Saturated brine (125ml) was added to the flask, and then diethyl ether (125ml) was added during the treatment. The quenched reaction was transferred to a 1L separatory funnel. The upper layer was stored and the lower aqueous layer was extracted with diethyl ether (2X 125 ml). These ether extracts were combined with the original extract and then washed with 1M hydrochloric acid (125ml), brine (125ml) and water (50 ml). The organic phase is passed through anhydrous Na₂SO₄The powder was dried, filtered and the filter cake was washed with dichloromethane (2 × 50ml) and the washings were combined with the filtrate. The volatiles were removed (rotary evaporator/vacuum/water bath at 40 ℃) to obtain a yellow liquid which solidified upon standing. The solid was crystallized from EtOAc-hexanes and the first crop (5.31g) was obtained. Will be femaleThe solution was concentrated and crystallized to give a second crop (1.36 g). Mother liquors from the second crystallization were applied on Biotage with a gradient of EtOAc-hexanes [ 20% (2CV), 20% -100% (8CV), 100% (2Cv)]Eluted 25g silica column was purified and fractions were collected in 16X 150mm tubes. 250mg of product was obtained by chromatography. (1R,4R,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]The combined yield of hepta-3, 6-dione (5) was 6.8g (94% yield).

Example 3(c)

Preparation of (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) by TPAP oxidation

Will be equipped with an overhead stirrer and serum cap/thermocouple/N₂A2 liter 3-necked round bottom flask with needle was loaded with (1R,4R,6S,7R) - (+) -7-bromo-6-hydroxy-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] in dichloromethane (400ml)]-hept-3-one (25) (12g, 36.8mmol, 1 equiv.), 4-morpholine-N-oxide (12.9g, 110mmol, 3 equiv.), and 4A molecular sieve powder. A catalytic amount of TPAP (25mg, 0.07mmol, 0.002 equiv.) was then added. The solution was stirred at room temperature under nitrogen as a green solution that darkened over time. The reaction was monitored daily by LC-MS. On day 2, the reaction stagnated and passed through using a filter flask and a vacuum sourceThe pad filters the reaction. The solution was returned to a 2 liter 3-neck round bottom reaction flask and fresh 4-morpholine-N-oxide (5.5g), 4A molecular sieve powder (10g) and TPAP (25mg) were added. The reaction was arrested later on day 3, and the reaction was filtered and restarted with fresh NMO (5.5g), 4A sieve (10g) and TPAP (25 mg). At the end of day 4, -7% of bromohydrin remained, and the TPAP oxidation reaction was therefore worked up. Using a Buchner flask and vacuum source, the flask was sealed by filling with 1/2-cm sand, 1/2-cm anhydrous Na₂SO₄A plastic sintered funnel of powder and 1-cm thick diatomaceous earth was filtered to remove solids from the reaction solution. The filter cake was washed with dichloromethane (2X 100ml and 50ml) until the filtrate stream was colourless. The filtrate was concentrated to a dark golden oil (rotary evaporator/vacuum/water bath at 40 ℃), which appeared on the glass surfaceShowing evidence of curing. The crude product was split in half and each half was subjected to chromatography on silica gel (100g) eluted with an EtOAc-hexanes gradient of 20% (lCV), 20% -100% (7.5CV) and 100% (4CV) on Biotage, and the fractions were collected in 25 x 150mm tubes. The product fractions from both chromatographs were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to obtain a white powder.

The powder was crystallized from EtOAc-hexanes to give the first crystals (8.5 g). The mother liquor was concentrated and crystallized to give a second crop (1.5 g). The combined yield of (1R,4R,7R) - (+) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] hepta-3, 6-dione (5) was 10g (80%).

Example 4

Preparation of (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] heptan-3-one (6)

Method A

Reacting (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Hepta-3, 6-dione (5) (1.00g, 3.09mmol) and 2- ((difluoromethyl) sulfinyl) pyridine (20) (715.10mg, 3.70mmol, 1.2 eq) were added to a round-bottomed flask and purged with argon. DMF (15mL) was added and the reaction was cooled to between-55 ℃ and-65 ℃. KO was added via syringe pump over 1h^tBu (623.0mg, 5.55mmol, 1.8 eq, 0.5M in DMF). The temperature was maintained between-55 ℃ and-65 ℃. After the addition was complete, the reaction was stirred at-60 ℃ for an additional 30 min. Adding saturated NH₄Cl (5.00mL), and the reaction was stirred at-60 ℃ for 5min before adding 6M HCl (5.00 mL). After stirring at-60 ℃ for 5min, the reaction mixture was warmed to room temperature and then to 65 ℃ for 1 h. After cooling, the reaction was diluted with brine, extracted with ethyl acetate (2 × 20mL), and washed with brine (10 mL). Through Na₂SO₄Drying and concentration gave a yellow oil which was purified via flash chromatography to give a white solid (620.0mg, 1.73mmol, 58% yield).m.p.85-87℃；¹H NMR(500MHz,CDCl₃) δ 7.14(d, J ═ 8.4Hz,1H),6.86(d, J ═ 8.5Hz,1H),4.60(d, J ═ 14.6Hz,1H),4.19(s,0H),4.14(s,0H),3.90(d, J ═ 14.7Hz,1H),3.79(s,1H),3.00(s,0H),2.83(dq, J ═ 14.6,3.0Hz,1H),2.27(d, J ═ 15.2Hz, 1H). See fig. 1.¹³C NMR (126MHz, CDCl3) δ 173.0,159.5,153.9(dd, J287.5,283.8 Hz),129.7,127.5,114.3,87.1(dd, J24.9, 23.5Hz),63.4,63.3,55.3,50.8(d, J17.1 Hz),44.6, 24.8. See fig. 2.¹⁹F NMR(376MHz,CDCl₃) Delta-88.15 (dp, J ═ 55.1,2.7Hz), -88.88(dq, J ═ 54.8,2.8 Hz). See fig. 3. IR (film, cm)^-1)3013,1785,1683,1551, respectively; for C₁₅H₁₄BrF₂NO₂+Na⁺HMRS (ESI)⁺) The calculated values are: 380.0074, respectively; found 380.0075.

Method B

2- (Difluoromethylsulfonyl) pyridine (20) (2.5g, 12.94mmol, 1.2 equiv.) and (1R,4R,7R) - (+) -7-bromo-2- (4-methoxy-benzyl) -2-azabicyclo [2.2.1]Hepta-3, 6-dione (5) (3.5g, 10.8mmol, 1 eq.) was combined in a round bottom flask with stir bar to which dimethylformamide (32ml) was added. The resulting yellow solution was capped with serum/N₂The needle/thermocouple was sealed and cooled to-40 ℃. A solution of potassium bis (trimethylsilyl) amide (KHMDS) (15.1ml, 15.1mmol, 1.4 equivalents) was added and the temperature was maintained between-40 deg.C and-35 deg.C. As the base was added, the reaction solution became dark orange. The resulting reaction mixture was stirred at-40 ℃ for 1 hour and then allowed to gradually warm to room temperature. Reacting with saturated NH₄The Cl solution (10ml) was quenched, stirred for 10 minutes, 3M hydrochloric acid (40ml) was added, stirred for 10 minutes, and then the flask contents were heated in a heating bath at 60 ℃ for 1.5 hours, and then cooled to room temperature. Water (35ml) was added and the reaction was extracted with tert-butyl methyl ether (MTBE) (3X 75 ml). The ether extracts were combined in one portion and washed with brine, anhydrous Na₂SO₄The powder was dried and filtered through a Chem-R-Us plastic sinter funnel to remove the used desiccant. The filtrate was concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to obtain a light brown oil. The crude product was passed over EtOA on a 100g silica column on Biotagec-Hexane gradient [ 15% (1CV) 15% -75% (7.5CV) 100% (3CV)]And fractions were collected in 16 x 100mm tubes. The product fractions were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) into a golden yellow liquid which was pumped on a vacuum line for several hours to yield (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1 ℃]Hept-3-one (6) (2.5 g; 63%).

Method C

To (1R,4R,7R) -7-bromo-2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]A solution of hepta-3, 6-dione (5) (48.5g, 149.6mmol, 1 equiv.) and 2- ((difluoromethyl) sulfinyl) pyridine (20) (31.8g, 164.6mmol, 1.1 equiv.) in DMF (800mL) was added dropwise very slowly to a solution of t-BuOK (30.2g, 269.3mmol, 1.8 equiv.) in DMF (800mL) at-57 deg.C to-52 deg.C. The reaction was stirred at-55 ℃ for 0.5h, then saturated NH was added at a temperature below-30 ℃₄A Cl solution (400mL) was slowly added dropwise to the reaction mixture. After addition, 6N HCl solution (360mL) was added to the above mixture at below-20 ℃. The mixture was warmed to 10 ℃ and stirred at 65 ℃ for 1 h. TLC (petroleum ether: ethyl acetate: 3:1, R)_f0.50) shows a new point. The mixture was added to water (4L) and extracted with MTBE (2L × 2). The organic layer was separated and washed with brine (2L) then Na₂SO₄Dried and concentrated under reduced pressure to give a residue as a red oil. The crude product was purified by column chromatography on silica gel with petroleum ether: ethyl acetate (20: 1-1: 1) to give (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1] as a white solid]Hept-3-one (6) (32.5g, 90.7mmol, 60.6% yield).

Example 5

Preparation of (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] heptan-3-one (7)

Method A

Reacting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-azabicyclo [2.2.1]Hept-3-one (6) (140mg, 0.39mmol) was added to MeCN (2.0mL) and cooled to 0 ℃. Is added dropwise to H₂O(075mL) of cerium ammonium nitrate (643.5mg, 1.17mmol, 3 equivalents). The reaction was allowed to warm to room temperature and stirred for 1 h. After completion, water was added and the solution was extracted with ethyl acetate (2 × 15 mL). Subjecting the organic layer to Na₂SO₄Dried and concentrated under reduced pressure. Flash chromatography yields (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1] as a white solid]Hept-3-one (7) (75mg, 0.315mmol, 80% yield). m.p.139-141℃；¹H NMR(500MHz,CDCl₃) δ 5.87(s,1H),4.41(s,1H),4.32(s,1H),2.96(s,1H),2.87(dq, J ═ 15.4,3.4Hz,1H),2.32(d, J ═ 15.2Hz, 1H). See fig. 4.¹³C NMR(126MHz,CDCl₃) δ 174.9,153.5(t, J ═ 287.5Hz),88.7(t, J ═ 24.1Hz),60.6,51.5,50.3, 24.3. See fig. 5.¹⁹F NMR(376MHz,CDCl₃) Delta-88.60 (dq, J ═ 55.1,2.8Hz), -88.88(dp, J ═ 54.6,2.5 Hz). See fig. 6. IR (film, cm-1)3249.1788,1678,1397; for C₇H₆BrF₂NO+H⁺Calculated HMRS (ESI +) of: 237.9679, respectively; found 237.9678.

Method B

An aqueous solution of cerium (IV) ammonium nitrate (CAN) (6.4g, 11.67mmol, 2.94 equiv.) in 20ml of distilled water was prepared 10 minutes before the oxidative cleavage reaction was carried out. Reacting (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2- (4-methoxybenzyl) -2-aza-bicyclo [ 2.2.1%]Hept-3-one (1.4g, 3.91mmol, 1 eq.) was dissolved in acetonitrile (70ml) and stirred with a stir bar in a round bottom flask. Aqueous CAN solution was added dropwise to the flask and the resulting mixture was stirred at room temperature for several hours, monitoring the progress of the reaction by HPLC and LCMS. The reaction was worked up by pouring the reaction into a 500ml separatory funnel, and then EtOAc (300ml) was added, shaken, and the upper layer was saved. The lower aqueous layer was extracted with more EtOAc (2X 50 mL). The ethyl acetate extracts were combined in one portion and washed with water (4X 10ml) and saturated brine (25ml)Then passing through anhydrous Na₂SO₄And (5) drying. After filtration through a plastic sintered funnel to remove the used desiccant, the filtrate was concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to obtain a light brown oil. The crude product was passed through an EtOAc-hexane gradient [ 15% (1CV) 15% -75% (7.5CV) 100% (3CV) on a 25g silica column on a Biotage]And fractions were collected in 16 x 100mm tubes. The product-containing fractions were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to a golden yellow liquid which was pumped on a vacuum line for several hours to yield purified (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1 ℃]Hept-3-one (7) (0.65 g; 70%).

Example 6

Preparation of methyl (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] heptan-3-one (8) and (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9)

Method A

Reacting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]Hept-3-one (7) (890.0mg, 3.74mmol) was added to dichloromethane (18.0mL), followed by the sequential addition of Boc₂O (978.8mg, 4.49mmol, 1.2 equiv.), DMAP (45.7mg, 0.37mmol, 0.1 equiv.), and Et₃N (0.78mL, 5.61mmol, 1.5 equiv). The reaction was stirred for 1h and then washed with 1M HCl (10mL) over Na₂SO₄Dried and concentrated. The resulting compound containing (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [ 2.2.1%]The oil of hept-3-one (8) was dissolved in methanol (18.0mL), and K was then added₂CO₃(1.55g, 11.21mmol, 3.0 equiv.) and the reaction stirred for 6 h. After completion, the reaction was diluted with brine and extracted with ethyl acetate (3 × 200mL) as indicated by LC/MS (methanolysis of the lactam occurred within the first 10 min). In the presence of Na₂SO₄After drying, concentration and purification by flash chromatography, (S) -methyl 3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) was obtained as a white solid (570mg, 1.97mmol, 52% yield).m.p.95-97℃；¹H NMR(500MHz,CDCl₃) δ 6.58(s,1H),5.50(d, J ═ 9.1Hz,1H),4.63(d, J ═ 8.7Hz,1H),3.75(s,3H),3.33(d, J ═ 20.4Hz,1H),3.21(dd, J ═ 20.3,2.7Hz,1H),1.42(s, 9H). See fig. 7.¹³C NMR(126MHz,CDCl₃) δ 164.3,154.7,154.6,152.4(t, J ═ 288.5Hz),150.1,140.6,135.5,88.9(dd, J ═ 21.8,20.2Hz),80.1,55.3,51.9,31.1, 28.3. See fig. 8.¹⁹F NMR(376MHz,CDCl₃) δ -84.49(d, J ═ 43.6Hz), -85.91(d, J ═ 43.4 Hz). See fig. 9. IR (film, cm)^-1)3347,2987,1773,1681, respectively; for C₁₃H₁₇F₂NO4+Na⁺HMRS (ESI)⁺) The calculated values are: 312.1023, respectively; found 312.1018.

Method B

To (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]A solution of heptan-3-one (7) (14.4g, 60.5mmol, 1 eq) in DCM (150mL) was added DMAP (739.0mg, 6.05mmol, 0.1 eq) and TEA (9.18g, 90.7mmol, 12.6mL, 1.5 eq). Then slowly add (Boc)₂O (15.8g, 72.6mmol, 16.6mL, 1.2 equiv.). After the addition, the mixture was stirred at 25 ℃ for 1 h. TLC (petroleum ether: ethyl acetate: 1, R)_f0.20) showed the reaction was complete. The mixture was adjusted to pH 3-4 with 1N HCl solution, then the organic layer was separated and washed with brine (100mL), Na₂SO₄Dried and concentrated under reduced pressure to give (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1] as a dark brown solid]Hept-3-one (8) (7.50g, crude), which was used in the next step without further purification. Reacting (1R,4R,7R) -7-bromo-6- (difluoromethylene) -2- (tert-butoxycarbonyl) -2-azabicyclo [2.2.1]Hept-3-one (8) (7.50g, 22.1mmol, 1 eq.) was dissolved in MeOH (55mL) and CH was added₃ONa (1.44g, 26.6mmol, 1.2 equiv.). The mixture was stirred at 0 ℃ for 1 h. TLC (petroleum ether: ethyl acetate: 1, R)_f0.70) showed the reaction was complete. Water (100mL) was added to the reaction mixture, and the mixture was usedMTBE (200 mL. times.2) extracted, washed with brine (150mL), Na₂SO₄Dried, filtered, and concentrated under reduced pressure to give a residue (crude) as a red solid. The crude product was purified by column chromatography on silica gel with petroleum ether: ethyl acetate (20:1 to 1:1) was purified to give methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) (5.20g, 17.9mmol, 81.0% yield) as a white solid.

Example 7

Preparation of tert-butyl (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -3-oxo-2-azabicyclo [2.2.1] hepta-2-carboxylate (8)

The dichloromethane (30ml) used in the reaction was deoxygenated with a gas dispersion tube and nitrogen before being used for the reaction. Reacting (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -2-azabicyclo [2.2.1]-heptan-3-one (7) (1.4g, 5.88mmol, 1 equiv.) and di-tert-butyl dicarbonate (2.56g, 11.73mmol, 2 equiv.) are dissolved in dichloromethane (30ml) in a 100ml round-bottom flask. 4- (dimethylamino) -pyridine (DMAP) (0.3g, 2.46mmol, 7.3 equivalents) was dissolved in triethylamine (6ml, 43mmol, 0.4 equivalents) and then the amine was added dropwise to the reaction under a nitrogen atmosphere blanket. The reaction mixture obtained in the flask was capped with serum/N₂The needle was sealed and the contents were stirred at room temperature for 1 hour. Small aliquots were removed and the reaction progress was checked by HPLC and LCMS. In the treatment, the volatiles were removed (rotary evaporator/vacuum/water bath at ambient temperature) to obtain a dark golden yellow liquid. The liquid was dissolved in dichloromethane (50ml) and partitioned with l M hydrochloric acid (25ml) and washed with brine (50 ml). Extracting with anhydrous Na₂SO₄The powder was dried, filtered, and the filtrate was concentrated (rotary evaporator/vacuum/water bath at ambient temperature) to provide a brown oil. The crude product was passed through an EtOAc-hexane gradient [ 15% (1CV) 15% -75% (7.5CV) 100% (3CV) on a 25g silica column on a Biotage]And fractions were collected in 16 x 100mm tubes. The fractions containing the product were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to a golden yellow liquid which was pumped on a vacuum lineDelivery continued for several hours, resulting in purified (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -3-oxo-2-azabicyclo [ 2.2.1%]Tert-butyl hepta-2-carboxylate (1.65 g; 82%).

Example 8

Preparation of (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19)

The solvent used in the reaction, methanol-water (3:1v/v), was deoxygenated with a gas dispersion tube and nitrogen immediately before use in the reaction. Reacting (1R,4R,7R) - (+) -7-bromo-6- (difluoromethylene) -3-oxo-2-azabicyclo [2.2.1]Tert-butyl (8) -hepta-2-carboxylate (1.6g, 4.73mmol, 1 eq) was dissolved in aqueous methanol (35ml) and stirred with a stir bar under a nitrogen atmosphere, and potassium carbonate powder (1.96g, 14.18mmol, 3 eq) was added to the solution in one portion. The reaction flask was sealed with a serum cap and a nitrogen needle, and the mixture inside was stirred for 12 hours. Dichloromethane (50ml) was added and the two phase crude reaction mixture was then acidified with 1M hydrochloric acid to break up excess potassium carbonate and bring the pH to 7(pH paper). The phases were separated and then the volatiles were removed from the dichloromethane layer. The crude product was passed through methanol-CH on a 25g silica column on Biotage₂Cl₂Gradient [ 1% (1CV) 1% -20% (7.5CV) 20% (3CV)]And fractions were collected in 16 x 100mm tubes. The product containing fractions were combined and concentrated (rotary evaporator/vacuum/water bath at 40 ℃) to a golden yellow solid which was pumped on a vacuum line for several hours to yield purified (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid (19) (0.733g, 56%).

Example 9

Preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid hydrochloride (1)

Method A

Methyl (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-ene-1-carboxylate (9) (570.0mg, 1.97mmol) was dissolved in dioxane (1.00mL) and 6M HCl (9mL) was added. After heating at 80 ℃ for 2h, the reaction was concentrated to give (S) -3-amino-4- (difluoroylidene) as a light brown powderMethyl) cyclopent-1-ene-1-carboxylic acid hydrochloride (1) (403.0mg, 1.90mmol, 97% yield). Crystallization from ethanol/diethyl ether increases purity to>99％。 m.p.207 ℃ (decomposition);¹H NMR(500MHz,D₂o) δ 6.59(s,1H),4.70(s,13H),3.39(d, J ═ 20.5Hz,1H),3.33(d, J ═ 20.8Hz, 1H). See fig. 10.¹³C NMR(126MHz,D₂O) δ 167.2,153.0(dd, J-290.1,288.4 Hz),141.8,134.3,86.1(dd, J-26.6, 21.2Hz),54.8(d, J-5.7 Hz), 31.1. See fig. 11.¹⁹F NMR(470MHz,D₂O) δ -83.1(dq, J ═ 40.8,2.8Hz), -83.5(dq, J ═ 40.4,2.1 Hz). See fig. 12. IR (film, cm)^-1)3348,3075,2981,2883,2829,2600,2434,1771,1686, respectively; for C₇H₇F₂NO₂HMRS (ESI) of-H^-) The calculated values are: 174.0372, respectively; found 174.0369.

Method B

(S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) cyclopent-1-en-1-carboxylate (9) (5.20g, 17.9mmol, 1 eq.) was added to 4M HCl (g)/EtOAc (100mL) and the mixture was stirred at 20 ℃ -30 ℃ for 2 h. TLC (petroleum ether: ethyl acetate: 5:1, R)_f0) indicates that the starting material is completely consumed. The mixture was concentrated under reduced pressure to give (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid methyl ester hydrochloride (3.00g, crude, HCl salt) as a yellow solid, which was used in the next step without further purification. The above compound (3.00g, 13.3mmol, 1.0 equiv.) was added to MeOH (15mL) and LiOH. H was added at 20 deg.C-30 deg.C₂O (1.39g, 33.2mmol, 2.5 eq.) in H₂A solution in O (10mL) was added slowly to the above mixture. The mixture was stirred at 20-30 ℃ for 3 h. TLC (dichloromethane: methanol ═ 5:1, R)_f0.40) indicates that the starting material is completely consumed. The mixture was adjusted to pH 2-3 with 6M HCl solution and concentrated to give crude product, which was passed throughReverse phase HPLC (Agela C18330 g; mobile phase: [ water (0.1% HCl) -MeOH)](ii) a B%: 10% -20%, 20min, 70mL/min) to give (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid hydrochloride (1) (1.80g, 8.46mmol, 63.7% yield, 99.5% purity) as a white solid.

Example 10

Preparation of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid hydrochloride (1)

6M hydrochloric acid was prepared by mixing concentrated hydrochloric acid (10ml) and water (10 ml). The THF used in the reaction was deoxygenated with a gas dispersion tube and nitrogen immediately before use in the reaction. (S) -3- ((tert-butoxycarbonyl) amino) -4- (difluoromethylene) -cyclopent-1-ene-1-carboxylic acid (19) was dissolved in THF (2ml) and stirred in a 10ml round-bottom flask with stir bar. 6M hydrochloric acid (2ml) was added. The reaction mixture was stirred at room temperature for 2 hours and then THF and water were removed with a stream of active nitrogen overnight. The pink solid residue was pumped on a vacuum line for several hours to remove any residual solvent, yielding (S) -3-amino-4- (difluoromethylene) -1-cyclopentene-1-carboxylic acid hydrochloride (1) (-100 mg; 86%) as a pink solid.

It is understood that the examples and embodiments provided herein are exemplary examples and embodiments. Those of skill in the art will envision various modifications to the examples and embodiments consistent with the scope of the disclosure herein. Such modifications are intended to be covered by the claims.

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Process for the synthesis of (S) -3-amino-4- (difluoromethylene) cyclopent-1-ene-1-carboxylic acid

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