| abstract |
An enzymatic process for the stereoselective preparation of an enantiomer of a heterobicyclic alcohol of the general formula wherein X is O, S, NH, N- (C 1 -C 4) alkyl or CH 2, Y 1, Y 2 and Y 3 independently of one another are hydrogen or a substituent selected from the group consisting of halogen, C1-C4 alkyl, C1-C4 alkoxy, C1-C4 haloalkyl, nitro and cyano, the substituent NO2 is attached to the bicyclic ring at the 5th or 7th position and the chiral C1-atom has R or S configuration and its corresponding alcoholic racemate by successively carrying out the following reaction steps: (i) acylating the racemate with an acylation reagent under the action of an enzyme with a stereoselective esterifying activity; (ii) separating the unesterified compound from the ester obtained and isolating the desired substantially pure enantiomer of an alcohol of formula I or an ester thereof; (iii) subjecting the resulting hydrolysis ester to conversion to the corresponding alcohol enantiomer, characterized in that the undesired alcohol enantiomer is converted to the starting alcoholic racemate under alkaline conditions so that it can be reused. |