Synthesis and antibacterial activity of new 1-oxa-1-dethiacephalosporins

A series of 3-(deacetoxymethyl)-1-oxa-1-dethiacephalosporins (1) bearing the 7-(alpha-alkoxyimono)acyl side chain were synthesized and their antibacterial properties were examined in comparison with that of FK-749 (2). (Z)-2-(Ethoxyimino)-2-(2 aminothiazol-4-yl)acetic acid was found to be a prefered side chain in the 1-oxa series, and the derivative 18b with this side chain proved to be a potential broad-spectrum antibiotic not at all inferior to 2.