| 摘要 |
This invention relates to a novel process for making a cephem of formula II from 2-(3-amino-2-oxo-azetidin-1-yl)-2,3-butadienoate of formula I. In another aspect, this invention is concerned with a process of further converting a compound of formula II into an antibacterial cephem of formula III. <IMAGE> <IMAGE> +TR <IMAGE> In formulae I, II and III, R1 is hydrogen, a conventional amino protecting group or an acyl group; R2 is an aromatic heterocyclic or aryl group; R3 is a conventional carboxy protecting group or -CO2R3 taken together forms a physiologically hydrolyzable ester; and R4 is a group selected from the group consisting of C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, cyclic C3-6 alkyl, and aryl; and n is 0 or 2.
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