Novel sulfonic acid esters and their preparation

摘要

The invention relates to novel sulfonic acid esters of formula I <IMAGE> (I) wherein R1 is C5-C6cycloalkyl which is unsubstituted or substituted by C1-C7alkyl, unsubstituted or substituted phenyl, R2 is C1-C7alkyl, R3 is phenyl which is substituted by halogen or nitro, and the asterisk denotes a carbon atom that is either present in the preponderant number of molecules in the S configuration or in the preponderant number of molecules in the R configuration. These compounds can be prepared by enantio-selective reduction of 4-R1-substituted alpha -oxobutyric acid compounds and subsequent conversion of the resultant alpha -hydroxy group into the -OSO2-R3 group. The compounds of formula I are suitable intermediates for the preparation of ACE inhibitors or precursors thereof.