| Abstract: | New β-lactam antibiotics. Cephem derivatives with electron withdrawing substituents at position 3 Oxidation of the 3-formyl-2-cephem compound 1 according to Corey [6] gave 2-cephem-3-carboxylic esters 4a, b, c (Scheme 1), which proved to be useful intermediates for the synthesis of cephalosporins bearing in position 3 a methoxycarbonyl group (10a, b, c, d / Scheme 2) or a carboxy group (20, 25, 30/Schemes 3, 4). The 3-formyl-3-cephem compounds 31a, b could be transformed into cyano- (33a) or methoxyiminomethyl- (36a, c, d) cephems (Scheme 5), which represent further examples of cephalosporins with electron withdrawing groups in position 3. |
