Nuclear analogs of β-lactam antibiotics. IV. Synthesis of 1-oxo-Δ3-O-2-isocephems

Abstract

The synthesis of 7-β-phenoxyacetamido-3-methyl-1-oxo-Δ³-O-2-isocephem-4-carboxylic acid 14 is described. Condensation of amine 2 followed by β -lactam formation and ozonolysis gave the acid 5. This was converted to its trichloroethyl ester 8 and the ketal was hydrolyzed to give 9. Reduction of the azido function followed by amide formation gave 11. The trichloroethyl group was removed and the enol acid 12 closed to yield 13. Hydrogenolysis of the benzyl ester gave 14. The structural assignments to the compounds are discussed.