| 摘要 |
A process for preparing enantiomerically pure esters of the formula I (Ia and Ib)where the substituents have the following meanings:R1hydrogen or substituted or unsubstituted C1-C6-alkyl, C1-C6-alkoxy or Cl-C6-alkanoyl,R2 and R3independently of one another hydrogen or substituted or unsubstituted C1-C6-alkyl, C1-C6-alkoxy, C1-C6-alkanoyl, C1-C6-alkylthio, C1-C6-alkylsulfinyl or C1-C6-alkylsulfonyl,R4 and R5R4<> R5 and independently of one another hydrogen or substituted or unsubstituted C1-C6-alkyl or R4 and R5 form together with the carbon atoms to which they are bonded a substituted or unsubstituted C3-C6-cycloalkylidene,R6substituted or unsubstituted aryl, C1-C20-alkyl, C3-C20-alkenyl, C3-C20-alkynyl, C1-C20-alkoxy-C1-C20-alkylcomprises converting racemic compounds of the formula II,where the substituents R1 to R5 have the abovementioned meanings, with a lipase or esterase in the presence of vinyl esters of the formula III,where R6 has the abovementioned meaning, and R7 is hydrogen or methyl, into compounds of the formula I.
|
