| 摘要 |
The invention is concerned with a new process for the preparation of compounds of formula <IMAGE> I wherein R1 is trityl, acetyl, tetrahydropyranyl or cyclopentyl; R2 is hydrogen, hydroxy, lower alkyl, cycloalkyl, lower alkoxy, lower alkenyl, lower alkynyl, aryl, aryloxy, aryl-lower alkyl, aryl-lower alkoxy or heterocyclyl or heterocyclyl-lower alkyl; the lower alkyl, cycloalkyl, lower alkoxy, lower alkenyl, cycloalkenyl, lower alkynyl, aryl-lower alkyl, aryl, aryloxy, aryl-lower alkoxy, the heterocyclyl moieties being unsubstituted or substituted with at least one group selected from carboxy, amino, nitro, cyano, lower alkyl, lower alkoxy, hydroxy, halogen, -CONR21R22, -N(R22)COOR23, R22CO-, R22OCO- or R22COO-, wherein R21 is hydrogen, lower alkyl, or cycloalkyl; R22 is hydrogen or lower alkyl; R23 is lower alkyl, lower alkenyl or a carboxylic acid protecting group; Y is -S- and Z is -CH2- or Y is -CH2- and Z is -O-, by acylation of a compound of formula <IMAGE> II with an activated carboxylic acid derivative of formula <IMAGE> III wherein R3 is lower alkyl, and R1, R2, X, Y, Z have the significance given above; and it is further concerned with compounds of formula III.
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