Nuclear analogs of β-lactam antibiotics. X. Synthesis of 2-substituted desthiocephalosporins

Abstract
The syntheses of the desthiocephem system from the enol 2 is described. Thus conversion of 2 to its triflate 3 followed by treatment with the sodium salts of malonate esters gave the cyclized products 4a–c. Azide reduction followed by coupling of phenoxyacetic acid and hydrogenolysis gave the acids 7 and 8. Compound 15 was also prepared.