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Chemistry of cephalosporin antibiotics. 30. 3-Methoxy- and 3-halo-3-cephems

1975; American Chemical Society; Volume: 18; Issue: 4 Linguagem: Inglês

10.1021/jm00238a017

1520-4804

Robert R. Chauvette, Pamela A. Pennington,

Synthesis of β-Lactam Compounds

The exo-methylene group in esters of 7-acylamido- and 7-amino-3-methylenecephams was ozonized to give 3-hydroxy-3-cephems. Conditions are described to effect a selective N-acylation of a 3-hydroxy-3-cephem nucleus ester. Vilsmeier reagents converted 7-acylamido-3-hydroxy compounds to 3-halo-3-cephem derivatives. Diazomethane converted the 3-hydroxy compounds to 3-methoxy-3-cephem derivatives. Removal of the ester-protecting group at the C4-carboxyl afforded a select group of cephalosporins with direct halo and methoxy substitution at C3. A number of these compounds are potent antibiotics.