阅读说明：本技术 外消旋西酞普兰二醇的拆分精制方法 (Resolution refining method of racemic citalopram diol ) 是由 艾林 李新生 徐敏忠 赵颂扬 郭华栋 蒋国飞 马向阳 应嘉沛 于 2019-09-25 设计创作，主要内容包括：本发明公开了一种外消旋西酞普兰二醇的拆分精制方法,包括：对外消旋西酞普兰二醇和拆分剂交替使用溶剂A和溶剂B进行溶解-析晶操作,分别收集每次析晶得到的(S)-西酞普兰二醇盐和(R)-西酞普兰二醇盐；分别合并每次收集到的(S)-西酞普兰二醇盐和(R)-西酞普兰二醇盐进行进一步精制,得到(S)-西酞普兰二醇盐和(R)-西酞普兰二醇盐。本发明使用了少于理论上拆分剂的使用量,达到了文献报道拆分(S)-西酞普兰二醇的效果。通过改换溶剂,方便的回收(R)-西酞普兰二醇盐,减少了三废的排放量。(The invention discloses a resolution and refining method of racemic citalopram diol, which comprises the following steps: carrying out dissolving-crystallization operation on racemic citalopram diol and a resolving agent by alternately using a solvent A and a solvent B, and respectively collecting (S) -citalopram diol salt and (R) -citalopram diol salt obtained by crystallization each time; the (S) -citalopram diol salt and the (R) -citalopram diol salt collected each time were combined separately and further refined to give (S) -citalopram diol salt and (R) -citalopram diol salt. The method uses less than the theoretical use amount of the resolving agent, and achieves the effect of resolving (S) -citalopram diol reported in literatures. The (R) -citalopram dialkoxide is conveniently recycled by changing the solvent, and the discharge amount of three wastes is reduced.)

1. A method for resolving and refining racemic citalopram diol is characterized by comprising the following steps: carrying out dissolving-crystallization operation on racemic citalopram diol and a resolving agent by alternately using a solvent A and a solvent B, and respectively collecting (S) -citalopram diol salt and (R) -citalopram diol salt obtained by crystallization each time; the (S) -citalopram diol salt and the (R) -citalopram diol salt collected each time were combined separately and further refined to give (S) -citalopram diol salt and (R) -citalopram diol salt.

2. The method for resolving and refining racemic citalopram diol as claimed in claim 1, wherein the dissolving-crystallizing process of racemic citalopram diol and resolving agent in solvent A comprises: mixing a sample to be resolved, a resolving agent and a solvent A, heating to dissolve, cooling to crystallize, filtering, washing and drying to obtain (S) -citalopram dialkoxide; the procedure for the dissolution-crystallization operation using solvent B was: and (R) -citalopram dialkoxide is obtained by mixing the resolved sample after the (S) -citalopram dialkoxide is separated out with a solvent B, heating for dissolving, cooling for crystallizing, filtering, washing and drying.

3. The method for resolution and purification of racemic citalopram diol as claimed in claim 1, wherein said solvent A is isopropanol; the solvent B is one or more of methyl acetate, ethyl acetate, propyl acetate, butyl acetate and acetone.

4. The method for resolving and refining racemic citalopram diol as claimed in claim 1, wherein the (S) -citalopram diol salt is a salt of (S) -citalopram diol and D-di-p-toluene tartaric acid in a molar ratio of 2: 1; the (R) -citalopram dialkoxide is a salt formed by (R) -citalopram dialkoxide and D-di-p-toluene tartaric acid according to the molar ratio of 2: 1.

5. The method for resolving and refining racemic citalopram diol as claimed in claim 1, wherein the molar ratio of the racemic citalopram diol to the resolving agent is 1: 0.2-0.5 mmoL.

6. The process according to claim 1, wherein the solvent A is used for the dissolution-crystallization operation, and the solvent A is selected from the group consisting of: the volume of solvent A added is (3-10 mL) calculated by the weight of citalopram diol in the initial sample: 1g of a compound; during the dissolution-crystallization operation using solvent B: the volume of the added solvent B is (3-10 mL) calculated by the weight of citalopram diol in the initial sample: 1g of the total weight of the composition.

7. The process according to claim 1, wherein the solvent A is used for the dissolution-crystallization operation, and the solvent A is selected from the group consisting of: heating to dissolve the mixture, wherein the temperature is 40-80 ℃, and the time is 5-30 min; cooling and crystallizing at the temperature of 25-40 ℃ for 1-8 hours; during the dissolution-crystallization operation using solvent B: heating to dissolve the mixture, wherein the temperature is 40-80 ℃, and the time is 10-60 min; cooling and crystallizing at 25-40 ℃ for 4-24 hours.

8. The method of claim 1, wherein the step of further refining the obtained (S) -citalopram diol salt or (R) -citalopram diol salt comprises: mixing the (S) -citalopram dialkoxide or (R) -citalopram dialkoxide obtained by combination with isopropanol respectively, heating and pulping, cooling, filtering, washing, and drying the solid to obtain the (S) -citalopram dialkoxide or (R) -citalopram dialkoxide refined product.

9. The method for resolving and refining racemic citalopram diol as claimed in claim 8, wherein the volume ratio of isopropanol added during further refining is 1-20 mL based on the weight of the combined (S) -citalopram diol salt or (R) -citalopram diol salt: 1g of the total weight of the composition.

10. The method for resolving and refining racemic citalopram diol as claimed in claim 8, wherein the refining is carried out at a temperature of 40-80 deg.C for 1-6 h, at a cooling temperature of 25-40 deg.C for 0.5-4 h.

Technical Field

The invention belongs to the technical field of organic chemistry, and particularly relates to a resolution and refining method of racemic citalopram diol.

Background

Citalopram is used clinically mainly for the treatment of depression, the compound was first developed by Lundbeck, switzerland. The molecule has one chiral carbon atom and is a chiral drug, and the racemate of the molecule is used as a preparation in the early stage, but researches prove that the drug effect of the R enantiomer is weak and is only one percent of that of the S isomer. The preparation with its S isomer as active ingredient became escitalopram, marketed in the us in 2002. With the improvement of living standard, escitalopram gradually replaces citalopram which originally takes racemate as raw material. The preparation of chiral citalopram diol is therefore the key to the preparation of escitalopram.

At present, the S configuration is mainly obtained by resolution, and documents WO2006106531A1, US2009099375A1, CN201310303327.1 (publication number is CN103342664A) and Organic precursors and products International,2006,38,423 report resolution methods of racemic citalopram diol, and all resolving agents used are D-di-p-toluoyltartaric acid. The mass ratio of the racemic citalopram diol to the D-di-p-toluyltartaric acid is 2:1, and the resolution yield of the racemic citalopram diol and the D-di-p-toluyltartaric acid with the optical purity of more than 98 percent is 28 to 33 percent (the theoretical yield is 50 percent) as the result of only one resolution in the above documents. Since the remainder of the solvent removal after the resolution is a thick gum difficult to form a solid, there is no report on how to reuse the remaining about 20% of (S) -citalopram diol and (R) -citalopram diol, which results in a low resolution yield and a large amount of waste.

The literature reports that (R) -citalopram diol can be cyclized under the action of acid to obtain (S) -citalopram, (Bioprocess biosystem Eng 2013, 36: 1031-. Theoretically, after the (S) -citalopram diol is resolved, the remainder is alkalized to obtain a mixture of (R) and (S) -citalopram diol free base, and the mixture is reacted with L-di-p-toluylene tartaric acid to obtain (R) -citalopram diol salt. How to omit the operation, the optically pure (R) -citalopram dialkoxide can be conveniently obtained only by using the D-di-p-toluol tartaric acid, and the (S) -citalopram is synthesized by the optically pure (R) -citalopram dialkoxide, so that the cost of the (S) -citalopram can be greatly reduced, and the generation of waste can be reduced.

Document CN201310303327.1 reports a resolution yield of up to 44%, which is caused by calculation errors, and the correct calculation result is 35%, but the optical purity is only 93%. The document CN200410044335.X reports the resolution of racemic citalopram diol by a crystallization-inducing method, and the results of the document are not achieved in the experiment.

Disclosure of Invention

The invention aims to provide a method for resolving and refining racemic citalopram diol with high yield aiming at the defects of the prior art.

A method for resolving and refining racemic citalopram diol comprises the following steps: carrying out dissolving-crystallization operation on racemic citalopram diol and a resolving agent by alternately using a solvent A and a solvent B, and respectively collecting (S) -citalopram diol salt and (R) -citalopram diol salt obtained by crystallization each time; the (S) -citalopram diol salt and the (R) -citalopram diol salt collected each time were combined separately and further refined to give (S) -citalopram diol salt and (R) -citalopram diol salt.

Preferably, the solvent A is isopropanol; the solvent B is one or more of methyl acetate, ethyl acetate, propyl acetate, butyl acetate and acetone.

In the invention, when the solvent A is adopted for carrying out dissolving-crystallization operation, the precipitated product is (S) -citalopram dialkoxide; when the solvent B is adopted for carrying out dissolving-crystallization operation, the precipitated product is (R) -citalopram dialkoxide. After each crystallization, the corresponding citalopram dialkoxide was collected to complete the resolution of (S) -citalopram dialkoxide and (R) -citalopram dialkoxide.

In the present invention, when the solvent a or the solvent B is used for dissolution-crystallization, the number of dissolution-crystallization operations may be one or two or more, and the preparation and purification of (S) -citalopram dialkoxide and (R) -citalopram dialkoxide can be achieved by one or more dissolution-crystallization operations.

In the present invention, the solvent B is preferably ethyl acetate.

In the invention, the (S) -citalopram dialkoxide is a salt formed by (S) -citalopram diol and D-di-p-toluene tartaric acid in a molar ratio of 2: 1; the (R) -citalopram dialkoxide is a salt formed by (S) -citalopram diol and D-di-p-toluene tartaric acid in a molar ratio of 2: 1; it can also be said that the (S) -citalopram diol salt is a salt of 1mol of (S) -citalopram diol and 0.5mol of D-di-p-toluyltartaric acid; the (R) -citalopram diol salt is a salt formed by 1mol of (S) -citalopram diol and 0.5mol of D-di-p-toluylene tartaric acid.

In the invention, in a solvent A, the dissolving-crystallizing process of racemic citalopram diol and a resolving agent is as follows: mixing a sample to be resolved, a resolving agent and a solvent A, heating to dissolve, cooling to crystallize, filtering, washing and drying to obtain (S) -citalopram dialkoxide; the procedure for the dissolution-crystallization operation using solvent B was: and (R) -citalopram dialkoxide is obtained by mixing the resolved sample after the (S) -citalopram dialkoxide is separated out with a solvent B, heating for dissolving, cooling for crystallizing, filtering, washing and drying. When the dissolution-crystallization operation is carried out using the solvent B, the resolved sample after the precipitation of the (S) -citalopram dialkoxide comes from the following process: and (3) crystallizing the solvent A, filtering and washing to obtain a liquid, and removing the solvent from the liquid to obtain the resolution sample after the (S) -citalopram dialkoxide is separated out.

In the invention, the first citalopram diol racemic citalopram diol is obtained by reacting citalopram diol with a resolving agent, and preferably, the molar ratio of the citalopram diol racemic body to the resolving agent is 1: 0.2-0.5. More preferably, the molar ratio of the citalopram diol racemate to the resolving agent is 1: 0.3-0.4. The invention can adopt the resolving agent with the input amount less than the theoretical amount, can obtain the yield equal to or more than the theoretical input amount, improves the utilization degree of the resolving agent from another angle and reduces the product cost.

In the present invention, reference to the racemic citalopram diol refers to a racemic mixture comprising equimolar amounts of (S) -citalopram diol and (R) -citalopram diol.

Preferably, the resolving agent is D-di-p-toluyltartaric acid.

In the present invention, in the process of performing the dissolution-crystallization operation using the solvent a: the volume of solvent a added is (3-10 mL) calculated as the weight of citalopram diol (or converted weight) in the starting sample: 1g of a compound; namely, the volume weight ratio of the solvent A to the citalopram diol in the initial sample is (3-10 mL): 1g of a compound; more preferably (3 to 6 mL): 1g of a compound; during the dissolution-crystallization operation using solvent B: the volume of the added solvent B is (3-10 mL) calculated by the weight of the initial sample: 1g of a compound; namely, the volume weight ratio of the solvent B to the citalopram diol in the initial sample is (3-10 mL): 1g, more preferably (4 to 8 mL): 1g of the total weight of the composition.

In the present invention, in the process of performing the dissolution-crystallization operation using the solvent a: heating to dissolve the mixture, wherein the temperature is 40-80 ℃, and the time is 5-30 min; cooling and crystallizing at the temperature of 25-40 ℃ for 1-8 hours; during the dissolution-crystallization operation using solvent B: heating to dissolve the mixture, wherein the temperature is 40-80 ℃, and the time is 10-60 min; cooling and crystallizing at 25-40 ℃ for 4-24 hours.

In the present invention, the process for further refining the obtained (S) -citalopram diol salt or (R) -citalopram diol salt comprises: respectively combining the (S) -citalopram dialkoxide or (R) -citalopram diol salt obtained by each crystallization, respectively mixing the combined (S) -citalopram dialkoxide or (R) -citalopram dialkoxide with isopropanol, heating and pulping, cooling, filtering, washing, and drying the solid to obtain the (S) -citalopram dialkoxide or (R) -citalopram dialkoxide refined product.

In the present invention, when further refining, the volume ratio of isopropanol added is 1-20 mL based on the weight of the combined (S) -citalopram dialkoxide or (R) -citalopram dialkoxide: 1g of a compound; namely, the volume weight ratio of the added isopropanol to the obtained (S) -citalopram dialkoxide or (R) -citalopram dialkoxide is 1-20 mL: 1g of a compound; more preferably: 6-8 ml of the added isopropanol and the obtained (S) -citalopram dialkoxide: 1g of a compound; the volume weight ratio of the added isopropanol to the obtained (R) -citalopram dialkoxide is 8-10 ml: 1g of the total weight of the composition.

In the invention, the refining is further carried out at the beating temperature of 40-80 ℃ for 1-6 h, the cooling temperature of 25-40 ℃ and the crystallization time of 0.5-4 h.

As a preferred scheme, the method for resolving and refining the racemic citalopram diol comprises the following steps:

(a) dissolving (R, S) -citalopram diol and D-di-p-toluene tartaric acid (D-DTTA) in isopropanol, heating for reaction, cooling to separate out crystal solid, and drying to obtain a salt formed by the (S) -citalopram diol and half of the D-di-p-toluene tartaric acid; the molar ratio of (R, S) -citalopram diol to D-di-p-toluyltartaric acid (D-DTTA) is 1: 0.2-0.5 mmoL; preferably 1: 0.3-0.4; based on the (R, S) -citalopram diol added initially, the weight volume ratio of the (R, S) -citalopram diol to the isopropanol is 1g: 3-10 mL; further preferably, the weight volume ratio of (R, S) -citalopram diol to isopropanol is 1g: 3-6 mL; still more preferably 1g: 5-6 ml. The temperature is 40-80 ℃, the time is 5-30 min, the temperature reduction is 25-40 ℃, and the stirring crystallization time is 1-4 h;

(b) recovering isopropanol from the mother liquor obtained in the step (a), adding a solvent B into the obtained residue, heating for reaction, cooling to separate out crystals, filtering, washing, and drying the solid to obtain a salt formed by (R) -citalopram dialkoxide and half of D-di-p-toluyltartaric acid; the solvent B is methyl acetate, ethyl acetate, propyl acetate butyl acetate and acetone, and ethyl acetate is preferred. The weight-volume ratio of the residue obtained after recovering isopropanol from the mother liquor to ethyl acetate is 1g: 3-10 mL, and the preferable weight-volume ratio is 1g: 5-9 ml; still more preferably 1g: 6-8 ml. The raising temperature is 40-70 ℃, the time is 10-60 min, the lowering temperature is 25-40 ℃, and the stirring crystallization time is 4-24 h;

(c) after recovering ethyl acetate from the mother liquor obtained in the step (b), adding isopropanol into the obtained residue after recovering ethyl acetate, heating to react, cooling to separate out crystals, filtering, washing and drying the solids to obtain a salt formed by (S) -citalopram dialkoxide and half of D-di-p-toluylene tartaric acid; the weight-to-volume ratio of the residue after recovering the ethyl acetate to the isopropanol is 1g: 3-10 mL, more preferably 1g: 4 to 8ml, more preferably 1g: 5-6 ml. The temperature is 40-80 ℃, the time is 5-30 min, the temperature reduction is 25-40 ℃, and the stirring crystallization time is 1-4 h;

(d) after recycling isopropanol from the mother liquor obtained in the step (c), adding a solvent B into a residue of the mother liquor obtained after recycling isopropanol, cooling to separate out crystals after heating reaction, filtering, washing and drying solids to obtain a salt formed by (R) -citalopram diol and half of D-di-p-toluylene tartaric acid; the solvent is ethyl acetate; the weight-volume ratio of the residue after recovering isopropanol from the mother liquor to ethyl acetate is 1g: 3-6 mL. The raising temperature is 40-70 ℃, the time is 10-60 min, the lowering temperature is 25-40 ℃, and the stirring crystallization time is 4-24 h;

(e) finally, after ethyl acetate is removed from the mother liquor under reduced pressure, alkalization is carried out, toluene is extracted, the extracting solution is dried, the toluene is removed under reduced pressure, and the residue is crystallized by the toluene to recover (R, S) -citalopram diol;

(f) collecting the (S) -citalopram dialkoxide and the (R) -citalopram dialkoxide obtained in the steps (a) to (d) respectively; and (S) -citalopram dialkoxide and (R) -citalopram dialkoxide which are obtained are respectively refined twice by utilizing isopropanol, and the processes are respectively as follows: mixing (S) -citalopram dialkoxide (or (R) -citalopram dialkoxide) with a certain amount of isopropanol, heating and pulping, cooling, filtering, washing, and drying the solid to obtain the refined S) -citalopram dialkoxide (or (R) -citalopram dialkoxide). The weight-volume ratio of the citalopram dialkoxide to the isopropanol is 1g: 1-20 mL, the pulping temperature is 40-80 ℃, the pulping time is 1-6 hours, the reducing temperature is 25-40 ℃, and the stirring crystallization time is 0.5-4 hours.

Compared with the prior art, the invention has the beneficial effects that:

(1) the amount of the resolving agent used in the method is less than (for example, about 60-80%) of the theoretical amount of the resolving agent, so that the effect of resolving (S) -citalopram diol reported in the literature is achieved. The (R) -citalopram dialkoxide is conveniently recycled by changing the solvent, and the discharge amount of three wastes is reduced.

(2) The invention alternately separates out (S) -citalopram dialkoxide and (R) -citalopram dialkoxide through the transformation of solvent, theoretically nearly can achieve 100 percent of resolution yield, and greatly reduces the production cost.

(3) The invention refines the product by pulping rather than crystallizing, reduces the dosage of solvent, improves the crystallization yield, has simple and easy operation, and is suitable for industrialized production.

Drawings

FIG. 1 is a schematic flow chart showing the purification process of (S) -citalopram dialkoxide and (R) -citalopram dialkoxide according to the present invention.

Detailed Description

The present invention is further illustrated by the following specific examples.

Referring to FIG. 1, in the reported data and the experiments of specific resolution, the yield of the first resolution was about 30% calculated by the amount of racemic citalopram diol, and the chiral HPLC analysis of the mother solution after resolution (area normalization) revealed that the (S) -citalopram diol content was 33% and the (R) -citalopram diol content was about 67%, which is the result of many experiments. Thus, during the resolution of racemic citalopram diol with D-di-p-toluoyltartaric acid in an amount of 50% of the material, one molecule of resolving agent is combined with two molecules of diol. 25% of the resolving agent D-di-p-toluenediol will preferentially combine with 50% of the (S) -citalopram diol to form a salt, and about 25% of the resolving agent and (R) -citalopram diol will form a salt, and the system will form a stable balance. The results show that the salt of D-di-p-toluylene tartaric acid and two molecules of (S) -citalopram diol is preferentially separated out from the solution with about 15% of the temperature being reduced, the salt of the remaining D-di-p-toluylene tartaric acid and citalopram diol is difficult to separate out from the solution with about 35% of the salt of D-di-p-toluylene tartaric acid and citalopram diol, and the amount of D-di-p-toluylene tartaric acid is adjusted from 25-60% of the substance to obtain almost the same results. Based on the experimental results, the resolving agent with the amount of less than 50% of the substance can completely achieve the resolving effect, so that the using amount of the resolving agent can be reduced, and the resolving yield is not influenced. The resolution agent is theoretically required in an amount of about 35% (equivalent resolution agent should be 1mol of citalopram diol requiring 0.5mol of resolution agent, and 1mol of citalopram diol requiring about 0.35mol of resolution agent after modification) based on the actual resolution yield of about 30%, wherein the equilibrium system contains 25% of D-di-p-toluenediol and 50% of (S) -citalopram diol salt, 10% of D-di-p-toluenediol and 20% of (R) -citalopram diol salt, and about 30% of citalopram diol is in a free state, and as the temperature is lowered, the equilibrium is broken, about 15% of the salt formed by D-di-p-toluenediol and two molecules of (S) -citalopram diol is preferentially separated out of the solution, and the rest of the raw materials are dissolved in the system, thereby completing the first resolution.