PROCESS FOR THE SELECTIVE PREPARATION OF Z-ISOMERS OF 3-(2-SUBSTITUTED VINYL)CEPHALOSPORINS

摘要

Z-Isomers of compounds of general formula (IV): Äwherein R<1> is 2-(2-N-protected aminothiazol-4-yl)-2-alkoxyiminoacetyl or the like, R<1> is hydrogen or the like; R<3> is hydrogen, a carboxyl-protecting group or the like; and R<1> is alkyl or the likeÜ can be prepared at high selectivities and in high yields by reacting a compound of general formula (I): Äwherein R<1>, R<2> and R<3> are each as defined above; and R<4> is aryl or the likeÜ with a 4-substituted or -unsubstituted thiazole-5-carbaldehyde in a mixed solvent comprising a chlorinated hydrocarbon and a lower alkanol at a temperature of as low as +5 DEG C or below.