Nuclear analogs of β-lactam antibiotics. XI. Synthesis of 3-methyl-7-β-(phenoxyacetamido)-Δ3-desthiocephem-4-carboxylic acid

Abstract

Treatment of the acid 3 with triethylamine in refluxing tert-butyl alcohol gave the decarboxylated product 4 which was isomerized to the desired Δ3 isomer 5 using DBN. Reduction of the azido functions in 4 and 5 followed by coupling to phenoxyacetic acid and debenzylation gave the acids 11 and 8, respectively. Attempts to prepare dienic cephalosporins failed. The halogenation of 4 and 5 was studied and is discussed.