Substituted azetidinone aldehydes

Abstract

Chemical transformation of the dihydrothiazine ring of a cephalosporin into the dihydrooxazine ring (1-oxacephem) was accomplished utilizing the novel intermediate having the structure ##STR1## wherein R is an amino-protecting group and R.sup.1 is the residue of an ester group which can be removed readily without disrupting the remainder of the molecule as illustrated by phenoxyacetyl as R and benzhydryl as R.sup.1.

Dependencies are inferred from the claim text.