Verfahren zur Herstellung von enantiomerenreinen Estern

摘要

The invention relates to a method for producing enantiomer-free esters of formula (I) (Ia or Ib), where the substituents represent the following: R<1> is a hydrogen or a substituted or unsubstituted C1-C6-alkyl-, C1-C6-alkoxy-, or C1-C6-alkanoyl; R<2> and R<3> independently of each other are hydrogen or a substituted or unsubstituted C1-C6-alkyl-, C1-C6-alkoxy-, or C1-C6-alkanoyl-, C1-C6-alkylthio-, C1-C6-alkyl sulfinyl or C1-C6-alkyl sulfonyl-; R<4> is not equal to R<5> and independently of each other they are either hydrogen or an substituted or unsubstituted C1-C6-alkyl-, or together with the hydrogen atoms, to which they are bound, form a substituted or unsubstituted C3-C6-cyclo alkylidene; and R<6> is a substituted or unsubstituted aryl-, C1-C20-alkyl-, C3-C20-alkenyl-, C3-C20-alkynyl-, C1-C20-alkoxy-C1-C20-alkyl. The method is characterized in that racemic compounds of the formula (II), in which the substituents R<1> to R<5> have the meanings given above, are reacted with a lipase or esterase in the presence of vinyl esters of formula (III), where R<6> has the meaning given above and R<7> represents hydrogen or methyl, to form compounds of formula (I).