2-(2-AZETIDINON-N-YL)-2- AND 3-BUTENOIC ACIDS DERIVATIVES AND THEIR USE IN THE CEPHALOSPORINE SYNTHESIS

摘要

Esters of 2-(2-azetidinon-N-yl)-2- and 3-butenoic acids of formula (I), wherein X is an acylamino group, Y is a S-substituted dithio group or a sulfonylthio group, or X and Y are joined to form a group (a), wherein R<1> is the aliphatic, aromatic or arylaliphatic residue bound to the carbonyl of said acylamino group and R<2> represents a carboxy-protecting group. The compounds (I) are intermediates in the preparation of cephem derivatives unsubstituted in the 3-position.