Abstract
The syntheses and the antibacterial activities of new 3-dimethoxyphosphinylmethyl and 3-dihydroxyphosphinylmethyl cephalosporins I-(Z), II-(Z), III-(Z) and III-(E), possessing the chloromethylene or methoxyimino substituent at the α-position to the 7-(2-aminothiazol-4-yl)acetamido or 7-(thiazol-4-yl)acetamido moiety of the cephem nucleus, are described. The key steps of these syntheses were the Michaelis-Arbusov reaction of the 3-halomethylcephem 1 with trimethyl phosphite and the dealkylation reactions of both the dimethoxyphosphinyl group and the p-methoxybenzyl ester of 7a, b-(Z) by treatment with bromotrimethylsilane to afford 9a, b-(Z).
