| 摘要 |
The invention relates to novel sulfonic acid esters of formula I <IMG> ( I ) wherein R1 is C5-C6 cycloalkyl which is unsubstituted or substituted by C1-C7 alkyl, or is phenyl that may be substituted by one or more substituents selected from the group consisting of C1-C7 alkyl, hydroxy, C1-C7 alkoxy, C1-C7 alkanoyloxy, fluorine, C1-C7 alkylenedioxy, amino, C1-C7 alkylamino, di(C1-C7) alkylamino, C1-C7 alkanoylamino, carbamoyl, C1-C7 alkylcarbamoyl, di(C1-C7)alkylcarbamoyl, C1-C7 alkanesulfonylamino, sulfamoyl, C1-C7 alkylsulfamoyl, di(C1-C7)alkylsulfamoyl, C1-C7 haloalkyl, C1-C7 hydroxyalkyl and C1-C7 aminoalkyl, R2 is C1-C7 alkyl, 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.
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