Stereospecific synthesis of isocephalosporins and 2-oxa isocephalosporins

摘要

A process is described whereby a synthetically produced 4-styryl-cis-3,4-azetidinone is converted to an isocephalosporin or its 2-oxa analog. The process is based upon the condensation of enamine and imine synthons. Novel intermediate azetidinones are also disclosed. Control of the stereochemical course of the process allows economical, high yield preparation of the racemic form of the product or when a single enantiomer of the imine synthon derived from the beta -hydroxy- alpha -amino acid starting material is used, both enantiomers of the product may be prepared and separated without optical resolution.