Method for producing 2-methylspiro(1,3-oxathiolane-5,3')quinuclidine

Abstract: A method for producing 2-methylspiro(1,3-oxathiolane-5,3')quinuclidine, which comprises reacting 3-hydroxy-3-mercaptomethylquinuclidine or a salt thereof and a carbonyl compound in the presence of a catalyst made of at least one member selected from the group consisting of tin halides, oxyacids of phosphorus, phosphorus oxyhalides and organic sulfonic acids, to produce cis-form 2-methylspiro(1,3-oxathiolane-5,3')quinuclidine or a salt thereof.

Description: The present invention relates to a method for industrially advantageously producing cis-form 2-methylspiro(l,3-oxathiolane-5,3')quinuclidine (hereinafter referred to simply as C-MSOQ) or a salt thereof useful for the treatment of diseases of the central nervous system in mammals, particularly for the treatment of diseases due to disturbances of central cholinargic function and autoimmune diseases which are so-called Sjoegren syndrome, or its intermediate. Particularly, the present invention relates to a method for producing C-MSOQ, and more particularly to a method for directly producing C-MSOQ by reacting 3-hydroxy-3-mercaptomethylquinuclidine (hereinafter referred to simply as QHT) or a salt thereof and a carbonyl compound in the presence of a certain specific catalyst. 2-Methylspiro(l,3-oxathiolane-5,3')quinuclidine (hereinafter referred to simply as MSOQ) can be produced by condensing QHT and acetaldehyde in the presence of a boron trifluoride-ethyl ether complex catalyst, as disclosed in e.g. published European Patent Application No. 0205247 and Japanese Unexamined Patent Publication No. 280497/1986. However, MSOQ as such a reaction product is usually obtained in the form of a mixture of geometrical isomers i.e. T-MSOQ (the one wherein the methyl group at the 2-position and the nitrogen atom at the 1'-position are located on the opposite sides of the plane of the 1,3-oxathiolane ring) and C-MSOQ (the one wherein the methyl group at the 2-position and the nitrogen atom at the 1'-position are located on the same side of the plane of the 1,3-oxathiolane ring. Then, C-MSOQ is isolated from the mixture of T-MSOQ and C-MSOQ as the above-mentioned reaction product by e.g. fractional crystallization. Further, US Patent No. 4,861,886 and Japanese Unexamined Patent Publications No. 16787/1989, No. 45387/1989 and No. 104079/1989 disclose methods wherein T-MSOQ is isomerized to C-MSOQ in the presence of a Lewis acid of a metal halide, sulfuric acid or an organic sulfonic acid as a catalyst. By the above conventional methods, the productivity of C-MSOQ can be improved to some extent. However, an industrially advantageous method has still been desired which is capable of further improving the productivity and reducing the production costs of C-MSOQ. For example, in each of the conventional methods, it is desired to simplify the reaction process steps and reduce the loads in the purification and separation steps by producing a large amount of C-MSOQ directly from QHT and acetaldehyde. Or, in the case where a mixture of T-MSOQ and C-MSOQ is firstly produced from QHT and acetaldehyde, it is desired to produce a large amount of C-MSOQ and to reduce the loads in the purification and separation steps by using a catalyst which is easy to handle and readily available on an industrial scale. The present inventors have conducted detailed studies on each step of the condensation reaction and the isomerization reaction and as a result, have surprisingly found that when a certain specific catalyst is present in the condensation reaction of QHT and acetaldehyde, rich C-MSOQ can be produced directly, and when QHT and acetaldehyde are reacted for condensation in the presence of a certain catalyst, a mixture of T-MSOQ and C-MSOQ is excellently produced, and when this mixture is reacted in the presence of a catalyst made of a tin halide, if necessary together with a certain cocatalyst, rich C-MSOQ can be produced. According to such methods of the present invention, a reaction product rich in C-MSOQ can be obtained in good yield, whereby purification and separation of C-MSOQ from the reaction product are easy, and the separation yield is high. Further, the catalysts used have no particular problems with respect to the availability and handling efficiency for an industrial operation. Furthermore, the reaction process can be simplified and the loads in the purification and separation steps can be reduced. Thus, the productivity of C-MSOQ can be remarkably improved. It is an object of the present invention to provide a method for producing C-MSOQ industrially advantageously. Another object of the present invention is to provide a method for industrially advantageously producing a reaction product of MSOQ rich in C-MSOQ. Accordingly, the present invention provides a method for producing MSOQ, which comprises reacting QHT or a salt thereof and a carbonyl compound in the presence of a catalyst made of at least one member selected from the group consisting of tin halides, oxyacids of phosphorus, phosphorus oxyhalides and organic sulfonic acids, to produce C-MSOQ or a salt thereof. In the present invention, QHT as the starting material, C-MSOQ, or a mixture of T-MSOQ and C-MSOQ, as the reaction product, includes salts thereof, such as salts thereof with inorganic acids or organic acids. Further, in the present invention, QHT, T-MSOQ, C-MSOQ or acid addition salts thereof include the respective racemic modifications and optical isomers of (d) and (e). When they are used as starting materials or intermediates for the above-mentioned reactions of the present invention, it is possible to produce the corresponding racemic modifications or optical isomers. Now, the present invention will be described. The carbonyl compound to be used in the present invention may be acetaldehyde, acetal or paraacetaldehyde. Among them, acetaldehyde is preferred. The starting material QHT can be produced by various methods. For example, it can readily be produced by reacting spiro(oxylane-2,3')quinuclidine with hydrogen sulfide, as disclosed in e.g. the above-mentioned published European Patent Application No. 0205247 or Japanese Unexamined Patent Publication No. 280497/1986, or by a method similar thereto. The catalyst to be used in the present invention is at least one member selected from the group consisting of tin halides, oxyacids of phosphorus, phosphorus oxyhalides and organic sulfonic acids. Specific examples of the catalyst component include stannic halides such as stannic chloride and stannic bromide; oxyacids of phosphorus such as phosphoric acid, phosphorus oxyhalides such as phosphorus oxychloride and phosphorus oxybromide; and organic sulfonic acids such as benzene sulfonic acid, o, m or p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid and anhydrides thereof. However, from the viewpoint of the ratio of T-MSOQ/C-MSOQ in the reaction product, the reaction yield, etc., a stannic halide, phosphoric acid, phosphorus oxychloride or p-toluenesulfonic acid is preferred. More preferred is stannic chloride or stannic bromide. Most preferred is stannic chloride. The amount of the catalyst component to be used, varies depending upon the types of the carbonyl compound and the solvent, the method for preparation of the catalyst, the reaction temperature, etc., and it can not be generally defined. However, it is usually from 1 to 5 mols, preferably from 2 to 3 mols, per mol of the starting material QHT or a salt thereof. In the reaction of QHT and the carbonyl compound, a solvent is usually employed. As such a solvent, any type may be employed so long as it is inert to the reaction. For example, at least one member selected from the group consisting of halogenated hydrocarbons such as chloroform, methylene chloride and 1,2-dichloroethane; aromatic hydrocarbons such as benzene, toluene and xylene; and aprotic polar solvents such as dimethylsulfoxide and dimethylformamide, may be employed. Preferred is at least one member selected from the group consisting of chloroform, methylene chloride, 1,2-dichloroethane, toluene and dimethylsulfoxide. Among them, chloroform is particularly preferred. The amount of the solvent can not generally be defined for the same reason as in the case of the amount of the above-mentioned catalyst component. However, it is usually from 500 to 10,000 parts by weight, preferably from 500 to 2,000 parts by weight, per mol of the starting material QHT or a salt thereof. The amounts of QHT or a salt thereof and the carbonyl compound in the method of this invention can not generally be defined, since they vary depending upon the types of the carbonyl compound, the catalyst and the solvent, the reaction conditions, etc. However, it is usual to use from 1 to 10 mols, preferably from 2 to 5 mols, of the carbonyl compound per mol of QHT or a salt thereof. In the method of the invention, a predetermined amount of the carbonyl compound is added to a solution having QHT or a salt thereof dissolved or dispersed in a solvent, and then a predetermined amount of the catalyst is added. Then, the reaction is carried out usually at a temperature of from -15 to +50°C, preferably from 0 to 20°C, for from 1 to 48 hours. If necessary, the reaction is conducted in a nitrogen atmosphere while supplying a nitrogen gas during the reaction. The reaction product containing MSOQ thus obtained is purified by washing, extraction or treatment with an aqueous sodium hydroxide solution, chloroform or sulfuric acid. Purified MSOQ may be extracted with a solvent such as n-hexane and obtained as an oily substance. However, it is also possible to supply hydrogen chloride gas or to add an isopropyl alcohol solution of hydrogen chloride, to the extract solution of MSOQ to convert it to an acid addition salt such as MSOQ hydrochloride and to obtain stable crystals. MSOQ composed of a mixture of trans-form and cis-form isomers thus obtained has the ratio of C-MSOQ to T-MSOQ increased, for example, to a level of at least 60/40 (weight ratio). Accordingly, it is readily possible to separate C-MSOQ or a salt thereof from such a mixture of trans-form and cis-form isomers by various methods such as column chromatography, fractional crystallization or their combination. By the method according to the present invention, a reaction product containing a large amount of C-MSOQ or a salt thereof can be obtained directly from QHT or a salt thereof and a carbonyl compound, as compared with the conventional method disclosed in e.g. the above-mentioned published European Patent Application No. 0205247, whereby it is possible to reduce the loads in the process steps for purifying and separating C-MSOQ or a salt thereof from the reaction product. In addition to such a merit, it is unnecessary to conduct two steps for the condensation reaction of QHT or a salt thereof and a carbonyl compound and the isomerization reaction separately, as required in the method disclosed in e.g. the above-mentioned US Patent No. 4,861,886. In the condensation reaction process of QHT or a salt thereof and the carbonyl compound in the present invention, a catalyst which is easy to handle and readily available on an industrial scale, is used, as compared with the conventional method disclosed in e.g. the above-mentioned published European Patent Application No. 0205248. Namely, the boron trifluoride·ethyl ether complex catalyst used in the conventional method is highly volatile and is not easy to handle, and not only that, it requires special treating operations for corrosion prevention of reactor and for waste water treatment. Besides, such a catalyst is expensive and hardly constantly available. Whereas, the above-mentioned catalyst used in the condensation reaction method of the present invention has no such drawbacks. Now, the present invention will be described in further detail with reference to Examples. However, it should be understood that the present invention is by no means restricted by such specific Examples. EXAMPLE 1 Into a 200 ml four-necked flask equipped with a stirrer, a thermometer and a calcium chloride tube, 3.46 g of 3-hydroxy-3-mercaptomethylquinuclidine (QHT) and 149.2 g of chloroform were charged and cooled to 4°C with ice water. Then, 3.96 g of acetaldehyde was added thereto. While maintaining the temperature at a level of from 5 to 10°C, 15.63 g of stannic chloride was dropwise added thereto over a period of about 30 minutes. Then, mixture was maintained at room temperature for 24 hours with stirring. To a white slurry-like reaction product, 50 g of water was introduced, and the product was dissolved. Then, 27 g of a 48% sodium hydroxide aqueous solution was dropwise added to convert the solution to strongly alkaline. The lower chloroform layer was separated, and 10 g of chloroform was added to the remaining aqueous layer for re-extraction. Then, to this chloroform layer, 23.4 g of 5% sulfuric acid was added for conversion to a sulfate, which was then extracted to water. Then, the solution was again made alkaline with 12.7 g of a 10% sodium hydroxide aqueous solution to free the desired product, which was then extracted four times with 8 g of n-hexane. The extract n-hexane layer was dried over anhydrous sodium sulfate, and then sodium sulfate was removed by filtration to obtain a hexane solution of 2-methylspiro(l,3-oxathiolane-5,3')quinuclidine (MSOQ). To this hexane solution, 3.6 g of a 15% hydrochloric acid/iso-propyl alcohol solution was dropwise added to obtain MSOQ hydrochloride. The precipitated white crystals were collected by filtration to obtain 3.67 g of a mixture of hydrochlorides of the cis-form and trans-form MSOQ (yield to QHT: 78%). The ratio of the cis-form to the trans-form of this mixture was analyzed by liquid chromatography, whereby C-MSOQ/T-MSOQ = 91/9 (weight ratio). EXAMPLE 2 Into a 200 ml four-necked flask as used in Example 1, 3.46 g of QHT and 74.5 g of chloroform were charged and cooled to 4°C with ice water. Then, 2.64 g of acetaldehyde was added thereto. While maintaining the mixture at a temperature of from 5 to 10°C, 13.8 g of phosphorus oxychloride was dropwise added over a period of about 30 minutes. Then, the mixture was maintained at room temperature for 24 hours with stirring. Post treatment was carried out in the same manner as in Example 1 to obtain 2.0 g of MSOQ hydrochloride (yield to QHT: 42.5%). The C-MSOQ/T-MSOQ ratio of this product was 65/35 (weight ratio). EXAMPLE 3 Into a 200 ml four-necked flask as used in Example 1, 3.46 g of QHT and 74.5 g of chloroform were charged and cooled to a temperature of from 10 to 15°C with ice water. Then, 2.64 g of acetaldehyde was added thereto. While maintaining the temperature at the same level, 4.41 g of 99% phosphoric acid was introduced thereto, and then the mixture was maintained at room temperature for 24 hours with stirring. Post treatment was carried out in the same manner as in Example 1 to obtain 1.4 g of MSOQ hydrochloride (yield to QHT: 29.7%). The C-MSOQ/T-MSOQ ratio of this product was 72/28 (weight ratio). EXAMPLE 4 Into a 200 ml four-necked flask as used in Example 1, 3.46 g of QHT and 74.5 g of chloroform were charged and cooled to a temperature of from 10 to 15°C with ice water. Then, 2.64 g of acetaldehyde was added thereto. While maintaining the temperature at the same level, 7.74 g of p-toluenesulfonic anhydride was introduced thereto, and then the mixture was maintained at room temperature for 24 hours with stirring. Post treatment was carried out in the same manner as in Example 1 to obtain 3.1 g of MSOQ hydrochloride (yield to QHT: 65.8%). The C-MSOQ/T-MSOQ ratio of this product was 67/33 (weight ratio). COMPARATIVE EXAMPLE 1 Into a 200 ml four-necked flask as used in Example 1, 3.46 g of QHT and 74.5 g of chloroform were charged and cooled to a temperature of from 0 to 5°C with ice water. Then, 2.64 g of acetaldehyde was added thereto. While maintaining the temperature at a level of from 5 to 10°C, 12.8 g of a boron trifluoride·ethyl ether complex compound was dropwise added thereto. Then, the mixture was maintained at room temperature for two hours with stirring. Post treatment was carried out in the same manner as in Example 1 to obtain 1.75 g of MSOQ hydrochloride (yield to QHT: 37.1%). The C-MSOQ/T-MSOQ ratio of this product was 58/42 (weight ratio). In the present invention, C-MSOQ or a salt thereof can be produced directly by reacting QHT or a salt thereof and a carbonyl compound in the presence of a certain specific catalyst, or it is possible to condense these starting materials in the presence of a certain catalyst to produce a mixture of T-MSOQ and C-MSOQ or salts thereof and then isomerize this mixture to C-MSOQ in the presence of a certain specific catalyst to obtain C-MSOQ or a salt thereof. By such methods, the reaction product contains a high proportion of C-MSOQ. Accordingly, it is possible to obtain a large amount of C-MSOQ or a salt thereof, or to reduce the loads in the steps of separating and purifying C-MSOQ from the reaction product. Accordingly, according to the present invention, it is possible to industrially advantageously produce C-MSOQ which is useful for the treatment of diseases of the central nervous system in mammals, particularly for the treatment of diseases due to disturbances of central cholinargic function and autoimmune diseases which are so-called Sjoegren syndrome.

Claims: A method for producing 2-methylspiro(1,3-oxathiolane-5,3')quinuclidine, which comprises reacting 3-hydroxy-3-mercaptomethylquinuclidine or a salt thereof and a carbonyl compound in the presence of a catalyst made of at least one member selected from the group consisting of tin halides, oxyacids of phosphorus, phosphorus oxyhalides and organic sulfonic acids, to produce cis-form 2-methylspiro(1,3-oxathiolane-5,3')quinuclidine or a salt thereof. The method according to Claim 1, wherein the catalyst is a stannic halide, phosphoric acid, phosphorus oxychloride, p-toluenesulfonic acid or a mixture thereof. The method according to Claim 1, wherein the reaction is carried out at a reaction temperature of from -15 to +50°C in the presence of from 1 to 5 mols of the catalyst per mol of 3-hydroxy-3-mercaptomethylquinuclidine. The method according to Claim 1, wherein the carbonyl compound is acetaldehyde. The method according to Claim 1, wherein the catalyst is stannic chloride. The method according to any one of Claims 1 to 5, wherein the reaction is carried out in the presence of a solvent.

Inventors: ANDO TAKAYOSHI, ARIYOSHI HAYATO, HAYASHI KOJI, ISOGAI TATSUO, KATSUYAMA ISAMU, KIMURA MASARU, NAKAMURA TADASHI, SAWAKI MASAHIKO, TOKUMOTO SHO, YOSHIZAWA HIROSHI, ANDO, TAKAYOSHI, ARIYOSHI, HAYATO, HAYASHI, KOJI, ISOGAI, TATSUO, KATSUYAMA, ISAMU, KIMURA, MASARU, NAKAMURA, TADASHI, SAWAKI, MASAHIKO, TOKUMOTO, SHO, YOSHIZAWA, HIROSHI, Ando, Takayoshi, Ishihara Sangyo Kaisha Ltd.,, Ariyoshi, Hayato, Ishihara Sangyo Kaisha Ltd.,, Katsuyama, Isamu, 346-2, Minamishimohara-cho,, Kimura, Masaru, Ishihara Sangyo Kaisha Ltd., Nakamura, Tadashi, Ishihara Sangyo Kaisha Ltd.,, Sawaki, Masahiko, Ishihara Sangyo Kaisha Ltd.,
Applicants: ISHIHARA SANGYO KAISHA, SNOW BRAND MILK PROD CO LTD, ISHIHARA SANGYO KAISHA, LTD., SNOW BRAND MILK PRODUCTS CO., LTD.
Application year: 1995
Main classification: C07D497
IPC codes: C07B61, B01J31, A61K31, A61P43, C07D453, A61P25, C07D497, B01J27