阅读说明：本技术 匹莫范色林及其中间体的制备方法 (Preparation method of pimavanserin and intermediate thereof ) 是由 郭四根 徐苗焕 于 2018-09-12 设计创作，主要内容包括：本发明公开了一种匹莫范色林及其中间体的制备方法,该中间体的制备方法包括下述步骤：在碱存在下,将化合物M在有机溶剂中,与化合物SM和二氧化碳反应,即得化合物A；其中,R为C<Sub>1</Sub>-C<Sub>4</Sub>的烷基、苄基或者取代的苄基,X为Cl、Br或I。本发明的制备方法操作简单,反应条件温和,收率较高,并且杂质含量低,易于纯化,能显著降低生产成本,易于工业化生产。<Image he="107" wi="700" file="DDA0001796640200000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>(The invention discloses a preparation method of pimavanserin and an intermediate thereof, and the preparation method of the intermediate comprises the following steps: in the presence of alkali, reacting the compound M with a compound SM and carbon dioxide in an organic solvent to obtain a compound A; wherein R is C 1 ‑C 4 And X is Cl, Br or I. The preparation method has the advantages of simple operation, mild reaction conditions, higher yield, low impurity content, easy purification and obvious effectThe production cost is reduced obviously, and the industrial production is easy to realize.)

1. A preparation method of a pimavanserin intermediate is characterized by comprising the following steps:

in the presence of alkali, reacting the compound M with a compound SM and carbon dioxide in an organic solvent to obtain a compound A; the reaction formula is as follows:

wherein R is C₁-C₄And X is Cl, Br or I.

2. The method of claim 1, wherein R is methyl, ethyl, or propyl;

the mol ratio of the compound SM to the compound M is (1.0-3.0) to 1.0;

the alkali is organic alkali or inorganic carbonate; the organic base is selected from one or more of triethylamine, DIEA, pyridine, DMAP and DBU; the inorganic carbonate alkali is selected from one or more of lithium carbonate, sodium carbonate, potassium carbonate and cesium carbonate;

and/or the organic solvent is one or more of N, N-methylformamide, acetonitrile, tetrahydrofuran and dioxane.

3. The process according to claim 1 or 2, wherein the molar ratio of the base to the compound M is (1.0-10.0) to 1.0;

and/or the temperature of the reaction is 0-50 ℃; the reaction time is 1-10 hours.

4. The process according to claim 3, wherein the molar ratio of the base to the compound M is (2.0-3.0) to 1.0;

and/or the temperature of the reaction is 15-30 ℃; the reaction time is 1-5 hours.

5. The preparation method of pimavanserin is characterized by comprising the following steps of:

(1) preparing compound a according to the preparation process as claimed in any one of claims 1 to 4;

(2) reacting a compound N with a compound A in an organic solvent in the presence of alkali to generate a compound B;

the reaction formula in the step (2) is as follows:

6. the process according to claim 5, wherein in the step (2), the molar ratio of the compound N to the compound A is (1.0-3.0) to 1.0;

in the step (2), the alkali is one or more of sodium methoxide, sodium ethoxide, sodium hydride, sodium amide, LDA, butyl lithium, tert-butyl lithium and potassium tert-butoxide;

in the step (2), the molar ratio of the alkali to the compound N is (0.2-1.0) to 1.0;

in the step (2), the organic solvent is one or more of toluene, tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether and methyl tert-butyl ether;

and/or, in the step (2), the temperature of the reaction is 80-110 ℃; the reaction time is 4-10 hours.

7. The method according to claim 6, wherein in the step (2), the molar ratio of the compound N to the compound A is (1.0-1.5) to 1.0;

in the step (2), the molar ratio of the alkali to the compound N is (0.2-0.6) to 1.0;

and/or, in the step (2), the temperature of the reaction is 95-105 ℃; the reaction time is 6-8 hours.

8. The preparation method of pimavanserin hemitartrate is characterized by comprising the following steps of:

s1: preparing compound B according to the preparation process as claimed in any one of claims 5 to 7;

s2: and salifying the compound B and tartaric acid to obtain the compound.

9. The method of claim 8, wherein in step S2, the molar ratio of compound B to tartaric acid is (1.0-3.0) to 1.0;

in the step S2, the salifying temperature is 0-100 ℃; the salifying time is 2-10 hours;

and/or in step S2, the solvent for salt formation is one or more of ethanol, isopropanol, isopropyl acetate, tetrahydrofuran, acetone and butanone.

10. The method of claim 9, wherein in step S2, the molar ratio of compound B to tartaric acid is (1.95-2.05) to 1.0;

in the step S2, the salifying temperature is 60-80 ℃; the salifying time is 4-6 hours;

and/or, in the step S2, the salifying solvent is ethanol and/or isopropanol.

Technical Field

The invention relates to a preparation method of pimavanserin and an intermediate thereof.

Background

Pimavanserin, or Pimavanserin, the hemitartrate of which is shown in formula I below, is a selective inverse agonist of the serum 5-hydroxytryptamine type 2A receptor (5-HT2A) developed by acardia pharmaceutical company and is mainly used for treating hallucinations and delusional disorders complicated with parkinson's disease.

The preparation of pimavanserin by the following reaction is disclosed in WO2006036874a 1:

the general route of the patent is long, and the process of preparing isocyanate uses virulent phosgene, so that the danger is high, and the method has high requirements on reaction equipment and the like, and is not beneficial to industrial scale-up production.

The use of Curtius rearrangement for the preparation of isocyanates is disclosed in US2008280886A, but the use of DPPA, which is expensive, is costly and not suitable for industrial production.

In the synthetic route disclosed in CN104961672A, phenyl N- (4-isobutoxybenzyl) carbamate, N- (4-fluorobenzyl) -1-methyl-4-piperidinamine and tartaric acid are reacted to generate pimavanserin hemitartrate, and in the early stage of the synthetic route, chloroformate with high toxicity is still used, and the total reaction steps are more and the reaction byproducts are more.

In the synthetic route disclosed in CN104844502A, N- (4-fluorobenzyl) -1-methyl-4-piperidinamine is reacted with chloroformate, wherein the R group in chloroformate is phenyl or p-nitrophenyl, chloroformate with higher toxicity is still used, and the number of byproducts in the reaction is large.

The synthesis route disclosed in CN105820110A, in which the acid salt of N- (4-fluorobenzyl) -1-methyl-4-piperidinamine is dissociated and then reacted with dicarbonyl imidazole to form an intermediate active urea compound, however, the imidazole impurity in this route is not easily removed in the post-treatment, and the content of impurity 1 in this synthesis route is high (about 8-15%).

The synthetic route disclosed in CN105153016A, in which 4-isobutoxybenzylamine reacts with dicarbonyl imidazole to form an intermediate active urea, but repeated experiments show that the imidazole impurity in this route is also not easily removed in post-treatment, and that the content of impurity 1 in this synthetic route is high (about 8-15%).

Disclosure of Invention

The invention provides a preparation method of pimavanserin and an intermediate thereof, aiming at overcoming the defects that a reagent used in the reaction in the existing synthetic route has high toxicity, or the contents of byproducts and impurities are high. The preparation method disclosed by the invention is simple to operate, mild in reaction conditions, high in yield, low in impurity content, easy to purify and easy for industrial production, and particularly has no impurity 1.

The invention solves the problems through the following technical scheme.

The invention provides a preparation method of a pimavanserin intermediate, which comprises the following steps:

in the presence of alkali, reacting the compound M with a compound SM and carbon dioxide in an organic solvent to obtain a compound A; the reaction formula is as follows:

wherein R is C₁-C₄And X is Cl, Br or I.

Among them, R is preferably methyl, ethyl or propyl.

Wherein the substituted benzyl group may be a substituted benzyl group as is conventional in the art, provided that the reaction can be carried out in accordance with common general knowledge in the art, typically an electron withdrawing group, and the substituted substituent is preferably a nitro group (-NO)₂)。

Wherein the molar ratio of compound SM to compound M is preferably (1.0-3.0): 1.0.

wherein, the carbon dioxide can participate in the reaction in different forms, for example, carbon dioxide gas can be introduced, or solid carbon dioxide, namely dry ice, can also be added. The pressure of the reaction is generally controlled to be 1.0MPa or less, according to common knowledge in the art.

The base may be, among others, a base conventional for such reactions, such as an organic base or an inorganic carbonate. The organic base is preferably one or more of triethylamine, DIEA, pyridine, DMAP and DBU; the inorganic alkali carbonate is preferably one or more of lithium carbonate, sodium carbonate, potassium carbonate and cesium carbonate. The molar ratio of the base to the compound A is preferably (1.0-10.0) to 1.0, more preferably (2.0-3.0) to 1.0.

Wherein, the organic solvent can be an organic solvent conventionally used for such reactions, generally an aprotic polar solvent, preferably one or more of N, N-methylformamide, acetonitrile, tetrahydrofuran and dioxane.

The methods and conditions of the reaction may be those conventional in the art for such reactions, among others. The temperature of the reaction is preferably 0 to 50 ℃ and more preferably 15 to 30 ℃. The reaction time is preferably 1 to 10 hours, more preferably 1 to 5 hours.

Among them, the compound M is commercially available, or can be obtained by further liberating an acetate salt of the commercially available compound M.

The invention also provides a preparation method of pimavanserin, which comprises the following steps:

(1) compound a was prepared according to the aforementioned preparation method of pimavanserin intermediate;

(2) reacting a compound N with a compound A in an organic solvent in the presence of alkali to generate a compound B;

the reaction formula in the step (2) is as follows:

in step (2), compound N is commercially available, or can be prepared by further liberating a commercially available hydrochloride of compound N.

In step (2), the group R in compound N is as defined above.

In the step (2), the molar ratio of the compound N to the compound A is preferably (1.0 to 3.0) to 1.0, more preferably (1.0 to 1.5) to 1.0.

In step (2), the base may be a conventional base for such a reaction, and preferably is one or more of sodium methoxide, sodium ethoxide, sodium hydride, sodium amide, LDA, butyllithium, tert-butyllithium, and potassium tert-butoxide. The molar ratio of the base to the compound N is preferably (0.2-1.0) to 1.0, more preferably (0.2-0.6) to 1.0.

In step (2), the organic solvent may be one or more of organic solvents conventionally used for such reactions, preferably toluene, tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether and methyl tert-butyl ether.

In step (2), the methods and conditions of the reaction may be those conventional in the art for such reactions. The reaction is generally carried out at reflux temperature, preferably at a temperature of from 80 to 110 deg.C, more preferably from 95 to 105 deg.C, for example 100 deg.C. The reaction time is preferably 4 to 10 hours, more preferably 6 to 8 hours.

The invention also provides a preparation method of the pimavanserin hemitartrate, which comprises the following steps:

s1: pimavanserin (i.e., compound B) was prepared according to the aforementioned method for preparing pimavanserin;

s2: salifying pimavanserin with tartaric acid to obtain the intermediate.

In step S2, the molar ratio of compound B to tartaric acid is preferably (1.0-3.0) to 1.0, more preferably (1.95-2.05) to 1.0, e.g., 2.0: 1.0.

In step S2, the methods and conditions for salt formation may be those conventional in such reactions in the art. The temperature for the salt formation is preferably 0 to 100 ℃, more preferably 60 to 80 ℃. The time for the salt formation is preferably 2 to 10 hours, more preferably 4 to 6 hours.

In step S2, the methods and conditions for salt formation may be those conventional in such reactions in the art. The solvent for salt formation is preferably one or more of ethanol, isopropanol, isopropyl acetate, tetrahydrofuran, acetone and butanone, more preferably ethanol and/or isopropanol.

On the basis of the common knowledge in the field, the above preferred conditions can be combined randomly to obtain the preferred embodiments of the invention.

The reagents and starting materials used in the present invention are commercially available.

The positive progress effects of the invention are as follows:

the preparation method disclosed by the invention is simple to operate, mild in reaction conditions, high in yield, low in impurity content, easy to purify, capable of obviously reducing the production cost and easy for industrial production.

Detailed Description

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention. The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions.

In the following examples, the detection method and conditions of HPLC are as follows:

a chromatographic column: 5 μm, Fortis C18 column, 250 mm. times.4.6 mm;

the mobile phase is shown in table 1 below:

TABLE 1

Operating time: 43 min; wavelength: 220nm/254 nm; column temperature: 35 ℃; flow rate: 1.0 mL/min.

The retention times of the partial substances were as follows:

pimavanserin: 15.46 min;

impurity 1: 28.32 min;

imidazole: 2.45 min.