Desulfurization of 7-Aminodeacetoxycephalosporanic Acid

Abstract

The Raney nickel desulfurization of 7-aminodeacetoxycephalosporanic acid (7-ADCA) was investigated to obtain 2-(3-amino-2-oxo-1-azetidinyl)-3-methyl-2-butenoic acid derivative (3a), a useful intermediate in a synthesis of monobactam compounds. The desulfurization of 7-ADCA gave a monocyclic β-lactam 3a and an unexpected 5-oxazolone derivative 5a. Compound 5a would be formed by the lactonization of alanyldehydrovaline derivative 4 derived from the hydrogenolytic cleavage of N-C4 bond of β-lactam ring in 7-ADCA. Similarly the desulfurization of cephalexin with Raney nickel gave the monocyclic β-lactam 3b and the 5-oxazolone derivative 5b. Compound 3a on treatment by the reported procedure gave 3-amino-2-azetidinone-1-sulfonic acid (7). Monobactam compounds 8 were obtained by acylation or arylation of 7. None of compounds 8a-e showed in vitro antibacterial activity against gram-positive and -negative bacteria.