PROCESS FOR PRODUCING OPTICALLY ACTIVE 2-ALKOXYCYCLOHEXANOL DERIVATIVES

Abstract: A process for efficiently producing (S,S)-2-alkoxycyclohexanols in a single step by using (± )-trans-2-alkoxycyclohexanols which are inexpensive and can be easily obtained. The process comprises treating a (± )-trans-2-alkoxycyclohexanol with a hydrolase originating in a microorganism and being capable of esterifying stereospecifically the R-isomer in the presence of an acyl donor under such conditions that no hydrolysis occurs substantially to thereby give (S,S)-2-alkoxycyclohexanols and (R,R)-2-alkoxycyclohexanol carboxylate and then taking up the (S,S)-2-alkoxycyclohexanols.

Description: Field of the Invention The present invention relates to a process for producing an optically active 2-alkoxycyclohexanol derivative, and more particularly, to a process for producing an (S,S)-2-alkoxycyclohexanol. Prior Art It is known that optically active 2-alkoxycyclohexanol derivatives such as (S,S)-2-alkoxycyclohexanol are important synthetic intermediates in the productions of medicines and agricultural chemicals. As a process for producing an optically active 2-alkoxycyclohexanol derivative, for example, the following methods have been investigated: 1 ○ the process in which a carboxylic ester of a (± )-trans-2-methoxycyclohexanol is hydrolyzed selectively in R-configuration in the presence of hydrolase to give a carboxylic ester of an (S,S)-2-alkoxycyclohexanol and an (R,R)-2-methoxycyclohexanol (Tetrahedron, 50 (35), 10521-30 (1994), Synthesis, 12, 1137-40 (1990), and J. Chem. Soc. Chem. Commun., 3, 148-50 (1989)), 2 ○ the process in which a carboxylic ester of a (± )-trans-2-methoxycyclohexanol is hydrolyzed selectively in S-configuration in the presence of hydrolase to give an (S,S)-2-methoxycyclohexanol and a carboxylic ester of an (R,R)-2-alkoxyhexanol (WO94/20634), and 3 ○ the process for obtaining an (R,R)-2-methoxycyclohexanol by asymmetric hydroboration of 1-methoxycyclohexene (J. Org. Chem., 53 (9), 1903-7 (1988)). Though the process 1 ○ is highly stereoselective, the configuration of an optically active 2-alkoxycyclohexanol obtained is (R,R)-configuration and a further hydrolysis of the carboxylic ester of (S,S)-2-alkoxycyclohexanol produced must be carried out in order to obtain (S,S)-2-alkoxycyclohexanol. Though (S,S)-2-alkoxycyclohexanol can be obtained through the process 2 ○, this method is not sufficiently stereoselective and there are some problems in productive efficiency and economical efficiency. A stereoselectivity of process 3 ○ is low, and further, there are such problems as reagents used in this process are expensive and etc. There is disclosed by Laumen, Kurt et al "Enzymic preparation of enantiomerically pure cyclohexanols : ester synthesis by irreversible acyl transfer" J.CHEM.SOC., CHEM.COMMUN. (1990), 49-51, a process for the preparation of enantiomerically pure cyclohexanols by using enantioselective esterification using vinyl acetate as acyl donor and Pseudomonas lipase. The reaction is disclosed for certain cylcohexanol derivatives including several alkoxy cyclohexanols. Taking an account of the above-mentioned circumstances, the object of the present invention is to provide a process for efficiently producing (S,S)-2-alkoxycyclohexanol in a single step from a (±)-trans-2-alkoxycyclohexanol which is inexpensive and easily available. The invention provides a process for producing an (S,S)-2-alkoxycyclohexanol as set out in claim 1 below. DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention is explained in more details. A (±)-trans-2-alkoxycyclohexanol which is used in this invention is a compound given in the above general formula (1). R 1 in the above formula is not specially limited to but includes a lower alkyl group such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, t-butyl, sec-butyl and the like; an alkenyl group such as vinyl, allyl, isobutenyl and the like; a cycloalkyl group such as cyclohexyl, cyclopentyl and the like; a substituted or unsubstituted aryl group such as p-nitrophenyl, a phenyl and the like; and a substituted or unsubstituted aralkyl group such as p-nitrobenyl, benzyl and the like. Among these, a methyl group is preferable. The above (±)-trans-2-alkoxycyclohexanol can be synthesized easily from cyclohexene oxide which can be obtained commercially, and a corresponding alcohol, for example, by the method which proposed in J. Am. Chem. Soc., 65, 2196 (1943). The acyl donor which is used in the present invention can be compounds expressed by the formula (5); R 3 OOCR 2 Wherein R 2 represents a hydrogen atom, straight-chain or branched alkyl group having 1 to 17 carbon atoms, or straight-chain or branched alkenyl group having 2 to 17 carbon atoms, and R 3 represents a vinyl group. R 2 mentioned above is not particularly limited to but includes a hydrogen; an alkyl group such as methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, sec-butyl, pentyl, heptyl and the like; and an alkenyl group such as vinyl, allyl, isopropenyl, isobutenyl and the like. Among these a propyl group is preferable. The above acyl donor preferably includes butyric anhydride, vinyl butyrate, tributyrin and so on. The hydrolase originating in a microorganism which is capable of esterifying the R-isomer stereospecifically, which is used in the present invention, is not particularly limited to but includes lipase, esterase, acylase, and so on. Preferable are a lipase derived from microorganisms which belong to Alkaligenes , a lipase derived from microorganisms which belong to Candida , a lipase derived from microorganisms which belong to Pseudomonas , a lipase derived from microorganisms which belong to Mucor , and the like. The above lipase derived from microorganisms which belong to Alkaligenes includes "Lipase PL" (a registered trademark of product of MEITO SANGYO Co.) and so on. The above lipase derived from microorganisms which belong to Candida includes "Novozym 435" (a registered trademark of product of Novo-Nordisk A/S), "Lipase OF" (a registered trademark of product of MEITO SANGYO Co.), "Lipase MY" (a registered trademark of product of MEITO SANGYO Co.) and so on. The above lipase derived from microorganisms which belong to Pseudomonas includes "Lipase PS AMANO" (a registered trademark of product of AMANO PHARMACEUTICAL Co.) and so on. The above lipase derived from microorganisms which belong to Mucor includes "Lipozyme IM" (a registered trademark of product of Novo-Nordisk A/S). The above hydrolase originating in microorganisms which is capable of esterifying the R-isomer stereospecifically can also be used in the form of microorganisms cells containing said hydrolase. The example of the above microorganism cells includes a yeast which belongs to Alkaligenes , Candida , Pseudomonas , Mucor and etc. and cells such as filamentous fungi, bacteria and so on. In the present invention, the above microorganism cells can be used in any treatment cells forms such as freeze-dried cells, cells treated by acetone, toluene and so on, cell homogenate, an extract from cells and so on. The above microorganism cells and treatment cells can be used as they are, or after immobilized. The producing process for an optically active 2-alkoxycyclohexanol derivative in the present invention can be carried out, for example, as follows. A (± )-trans-2-alkoxycyclohexanol as a starting material is dissolved in a solvent in the concentration of 0.1 to 70 w/v%, preferably 1 to 50 w/v%, and there are added 0.5 to 10 times equivalent, preferably 0.5 to 2 times equivalent of above-mentioned acyl donor to the (± )-trans-2-alkoxycyclohexanol and 0.001 to 10 parts by weight, preferably 0.01 to 1 parts by weight of the above-mentioned hydrolase which is capable of esterifying the R-isomer stereospecifically to the (± )-trans-2-alkoxycyclohexanol, and the solution was mixed under stirring to carry out asymmetric esterification. After completion of the asymmetric esterification, the hydrolase described above is recovered by filtration or centrifugation as insoluble material. Purified (S,S)-2-alkoxycyclohexanol and purified carboxylic ester of (R,R)-2-alkoxycyclohexanol are obtained by concentration and distillation of the filtrate. In the present invention, the asymmetric esterification described above is carried out under the condition where no hydrolysis reaction occurs substantially. For example, because hydrolysis which is reverse reaction of an above esterification proceeds in the case of the presence of water in the system, it is preferable that above-described asymmetric esterification is performed in the solvent that contains no water or a very little amount of water. The solvent used in the present invention is not particularly limited to but includes solvents which do not inactivate the hydrolase, for example, a hydrocarbon type solvents such as toluene, hexane and so on; ether type solvents such as diisopropyl ether, tetrahydrofuran, methyl tert-butyl ether and so on; ketone type solvents such as acetone and methyl ethyl ketone; and ester type solvents such as ethyl butyrate. In the present invention, the above asymmetric esterification can be carried out without the above solvent except the above substrate and the reaction reagent. The reaction temperature in the process of the above asymmetric esterification is preferably 0°C to 80 °C , and more preferably 10 °C to 50 °C . The reaction time in the process of the above asymmetric esterification is preferably 1 to 240 hours, and more preferably 1 to 72 hours. Best Mode for Carrying Out the Invention The invention will be described in more detail with reference to the following example, which are not intended to restrict the scope of the invention. Examples 1 to 6 The mixture of 260 mg of (± )-trans-2-methoxycyclohexanol, 1.27 ml of vinyl butyrate and 130 mg of various kinds of lipase was poured in 15 ml-screw tubes and a reaction was carried out for 24 hours at room temperature during agitating. The resulted reaction mixture was filtered. The conversion rate was determined by GC analysis of the filtrate. From the residual trans-2-methoxycyclohexanol, a derivative thereof was given (DNB derivative), and the optical purity was measured by HPLC analysis. Every configuration of the trans-2-methoxycyclohexanol was (S,S)-configuration. The conversion rate and the optical purity are shown in table 1. Examples 7 to 30 After 130 mg of (± )-trans-2-methoxycyclohexanol and 127 µl of vinyl butyrate were poured in 15 ml-screw tubes, dissolved in 1 ml of various kind of solvent, and there was added 65 mg of various kind of lipase. The mixture was reacted at 30 °C for 24 hours during stirring. The solution was filtered and the conversion rate was determined by GC analysis of the filtrate. From the residual trans-2-methoxycyclohexanol, a derivative thereof was given (DNB derivative), and the optical purity was measured by HPLC analysis. Every configuration of the trans-2-methoxycyclohexanol was (S,S)-configuration. The conversion rate and the optical purity are shown in table 2. Examples 31 to 54 After 130 mg of (± )-trans-2-methoxycyclohexanol and 127 µl of various kind of acyl donor were poured in 15 ml-screw tubes, dissolved in 1 ml of toluene, and there was added 65 mg of various kind of lipase. The mixture was reacted at 30 °C for 24 to 96 hours during stirring. The solution was filtered and the conversion rate was determined by GC analysis of the filtrate. From the residual trans-2-methoxycyclohexanol, a derivative thereof was given (DNB derivative), and the optical purity was measured by HPLC. Every configuration of the trans-2-methoxycyclohexanol was (S,S)-configuration. The conversion rate and the optical purity are shown in table 3. Industrial Applicability Because of the above-mentioned constitute according to the present invention, we can produce an (S,S)-2-alkoxycyclohexanol efficiently and easily, which are useful for intermediates on production of medicines.

Claims: A process for producing an optically active 2-alkoxycyclohexanol derivative which comprises treating a (±)-trans-2)-trans-2-alkoxycyclohexanol which is expressed by the general formula (1): (wherein R 1 represents an alkyl group having 1 to 4 carbon atoms or an alkenyl group) with a hydrolase derivable from microorganisms which belong to Alkaligenes, Candida, Pseudomonas or Mucor, in the presence of an acyl donor which is expressed by the following formula (5); R 3 OOCR 2 (wherein R 2 represents a hydrogen atom, straight-chain or branched alkyl group having 1 to 17 carbon atoms, or straight-chain or branched alkenyl group having 2 to 17 carbon atoms, and R 3 represents a vinyl group, under a condition with no water or very little amount of water in which no hydrolysis occurs, to thereby give an (S,S)-2-alkoxycyclohexanol which is expressed by the general formula (2); (wherein R 1 is the same as previously defined), and a carboxylic ester of an (R, R)-2-alkoxycycloheaxanol which is expressed by the general formula (3); (wherein R 1 is the same as previously defined and R 2 is the same as previously defined, and then taking up said (S,S)-2alkoxycyclohexanol. The process for producing an optically active 2-alkoxycyclohexanol derivative according to claim 1 wherein said (±)-trans-2-alkoxycyclohexanol is (±)-trans-2-methoxycyclohexanol. The process for producing an optically active 2-alkoxycyclohexanol derivative according to claim 1 or 2 wherein R 2 in the acyl donor expressed by the general formula (5) is a hydrogen atom, straight-chain or branched alkyl group having 2 to 17 carbon atoms, or straight-chain or branched alkenyl group having 2 to 17 carbon atoms. The process for producing an optically active 2-alkoxycyclohexanol derivative according to claim 1, 2 or 3 wherein the acyl donor is vinyl butyrate or vinyl capronate. The process for producing an optically active 2-alkoxycyclohexanol derivative according to claim 1, 2, 3 or 4 wherein said hydrolase is a lipase derivable from microorganisms which belong to Alkaligenes , a lipase derivable from microorganisms which belong to Candida , a lipase derivable from microorganisms which belong to Pseudomonas or a lipase derivable from microorganisms which belong to Mucor .

Inventors: HONDA MIZUHO, INOUE KENJI, KAN KAZUNORI, TAOKA NAOAKI, HONDA, MIZUHO, INOUE, KENJI, KAN, KAZUNORI, TAOKA, NAOAKI
Applicants: KANEKA CORP, KANEKA CORPORATION
Application year: 1996
Main classification: C12P41
IPC codes: C07C69, C12P41, C07C43, C07C67, C12R1, C12P7, C12N9