阅读说明：本技术 4-溴-2-(4’-乙氧基-苄基)-1-氯苯的制备 (Preparation of 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene ) 是由 胡林 徐涛 邱小龙 李小跃 左智伟 刘文博 储玲玲 袁希萌 邹平 于 2020-12-04 设计创作，主要内容包括：本发明的目的在于提供一种步骤更短、更绿色的合成4-溴-2-(4’-乙氧基-苄基)-1-氯苯的方法,为达格列净、索格列净和埃格列净等SGLT-2抑制剂药物的关键中间体生产提供更有效的合成策略。选择2-氯-5-溴苯甲酸与苯乙醚,在三氟乙酸酐存在下,以三氟化硼乙醚为催化剂,完成直接酰基化反应,不经处理,加入三乙基硅烷一锅反应得到目标化合物4-溴-2-(4’-乙氧基-苄基)-1-氯苯。(The invention aims to provide a method for synthesizing 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene in a shorter and greener step, and provides a more effective synthesis strategy for the production of key intermediates of SGLT-2 inhibitor drugs such as dapagliflozin, soagliflozin, egagliflozin and the like. 2-chloro-5-bromobenzoic acid and phenetole are selected, in the presence of trifluoroacetic anhydride, boron trifluoride ethyl ether is used as a catalyst to complete direct acylation reaction, and triethylsilane is added for one-pot reaction without treatment to obtain the target compound 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene.)

1. A method for synthesizing 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene in one pot, which has the following reaction formula:

the method is characterized in that: reaction of 2-chloro-5-bromobenzoic acid with phenetole in trifluoroacetic anhydride (TFAA) and catalytic amount of boron trifluoride etherate (BF)₃EtOEt), and then directly adding triethylsilane to react in one pot without treatment to obtain the target compound 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene.

Technical Field

The invention belongs to the field of compound synthesis methods, and particularly relates to synthesis of a compound 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene.

Background

SGLT-2 protein exists in the tubular cavity of glomerular epithelial cell of human body, and under the action of the SGLT-2 protein, the reabsorption rate of glucose filtered through renal tubules is as high as 90%, so that the biological action of the SGLT-2 protein is inhibited, and the purpose of reducing blood sugar can be achieved. As a novel hypoglycemic medicament, the unique hypoglycemic mechanism of the SGLT-2 inhibitor is irrelevant to insulin, is a new target of the hypoglycemic medicament independent of insulin, and has low risk of causing hypoglycemia. Compared with other hypoglycemic drugs, the hypoglycemic drug has a novel action mechanism and opens a new way for discharging the redundant glucose in blood. SGLT-2 inhibitors have unusual manifestations in reducing blood glucose, protecting cardiovascular system and kidney, and may even be used in combination with ascorbic acid and quinones for cancer treatment.

Currently, many SGLT-2 inhibitor drugs in China are in the research stage, such as Henggliflozin of Henry medicine, Ronggliflozin of Guangdong Dongyuang, Gaggezin of Shandong Xuanyao medicine, and the like. The main commercially available products are Dapagliflozin (Dapagliflozin), Canagliflozin (Canagliflozin), engagliflozin (Empagliflozin), ertuglozin (Ertugliflozin) luagliflozin (Luseogliflozin), rigagliflozin (Ipragliflozin), Tofogliflozin (Tofogliflozin), and sotalozin (Sotagliflozin). Their chemical structures are shown below:

as can be seen from the above, these SGLT-2 inhibitors share chemical structural similarities, all of which comprise a similar glycosyl group (a six-membered heterocyclic ring, primarily a tetrahydropyran ring) attached to an aryl group. Among them, dapagliflozin, egagliflozin and suagliflozin have the same aryl group, and the compound 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene is a common key intermediate for synthesizing them, for example, from which dapagliflozin is synthesized in US2004138439 as follows:

the synthesis of the compound 4-bromo-2- (4 '-ethoxy-benzyl) -1-chlorobenzene has been reported mainly as follows, in US2004138439, WO2010/22313a2 and WO2015/132803a2, 2-chloro-5-bromobenzoic acid is selected as an initiator, the initiator is subjected to acyl chlorination, then under the catalysis of aluminum trichloride, the precursor and phenetole are subjected to Friedel-crafts acylation reaction, the diaryl ketone compound is obtained by purification and separation, and then the aryl ketone compound is reduced to obtain 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene.

The method has the advantages of short steps, good selectivity and high yield, and has the defects of using a large amount of acid acyl chlorination reagents in the acyl chlorination reaction, generating acid wastes, using aluminum trichloride in the Friedel-crafts reaction and solving the problem of acid waste water, being not in line with the requirement of green production, and greatly increasing the corrosion resistance requirement and the maintenance cost of production equipment.

Another class of processes reported in patents CN107382679A, CN107573311A, CN107540648A and CN108084130A is based on Friedel-crafts alkylation. The method has longer steps, completes the construction of diarylmethane by Friedel-crafts alkylation reaction with benzyl alcohol or benzyl halide, has reaction steps of halogenation, Sandmeyer reaction and the like, has selectivity problems and some safety problems of alkylation reaction, and is not as efficient and convenient as acylation reaction.

Therefore, the existing acylation method for synthesizing 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene has the problems of using acid materials, generating acid waste gas (hydrogen chloride and the like) and acid waste water (aluminum trichloride and the like); the alkylation process has problems of long steps, poor selectivity and safety of reaction, which are very troublesome for industrial scale-up.

As mentioned above, SGLT-2 inhibitor hypoglycemic drugs have a broad market prospect, empagliflozin, dapagliflozin, etc. have become heavy pound varieties sold over $ 10 billion a year, 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene is used as a common key intermediate of dapagliflozin, egagliflozin and suagliflozin, and further development of efficient and green synthetic methods thereof is necessary.

Disclosure of Invention

The invention aims to provide a method for synthesizing 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene with shorter steps and more efficiency, which is used for the industrial production of some SGLT-2 inhibitor hypoglycemic drugs. The synthetic route of the invention is as follows:

2-chloro-5-bromobenzoic acid is used as an initiator to react with phenetole in the presence of trifluoroacetic anhydride (TFAA) and a catalytic amount of boron trifluoride ethyl ether (BF 3. EtOEt), and then triethylsilane is directly added to react in one pot without treatment to obtain the target compound 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene. The method has mild conditions, is simple and efficient, does not relate to the use of an acyl chlorination reagent and aluminum trichloride, only uses catalytic amount of boron trifluoride diethyl etherate and trifluoroacetic acid associated with the reaction as an acid catalyst, and completes acylation and reduction of carbonyl in one pot. Compared with the traditional synthesis method, the post-treatment is easy, the target can be obtained through simple washing, concentration and crystallization, meanwhile, the treatment of a large amount of acid gas, aluminum trichloride acid wastewater and other difficult-to-treat wastes is not involved, the method is green and environment-friendly, has good practicability, and is suitable for industrial amplification production and use.

Detailed Description

The present invention can be understood more specifically by the following examples, which are intended to be illustrative rather than limiting in scope, and various alternatives, modifications, and equivalents which may be apparent to those skilled in the art are intended to be included within the scope of the present invention.

EXAMPLE one Synthesis of 4-bromo-2- (4' -ethoxy-benzyl) -1-chlorobenzene

Trifluoroacetic anhydride (84.0g, 400mmol), phenetole (14.7g, 120mmol) and boron trifluoride etherate (1.42g, 10mmol) were added successively to a 250mL four-necked flask, and 2-chloro-5-bromo-benzoic acid (23.5g, 100mmol) was added in portions, and the mixture was heated to 30. + -. 5 ℃ with stirring and allowed to react for 6 hours to obtain a dark brown solution. The temperature is reduced to room temperature, triethylsilane (34.9g, 300mmol) is added, the temperature is raised to 55-60 ℃ again, and the reaction is kept for 18 h. After cooling, the mixture was concentrated under reduced pressure to remove the low-boiling solvent, and the residue was washed with methylene chloride (150mL) and a saturated sodium bicarbonate solution (60mL) to separate layers, and the organic layer was collected, washed twice with water (60 mL. times.2), and concentrated. The residue was recrystallized by addition of ethanol, filtered and dried by blowing at 40 ℃ to give the title compound (24.3g, yield 74.5%) as a white solid.