PREPARATION OF AZETIDINOOXAZOLE DERIVATIVES

摘要

A compound represented by the formula (II) epimerizes by the action of a base and the product is precipitated for shifting the equilibrium to yield the corresponding epimer represented by the formula (I). (II) (I) wherein Ar is an optionally substituted aryl or heterocyclic group; Tet is an optionally substituted tetrazolyl group and B1 and B2 are each ester forming group in the field of penicillin or cephalosporin chemistry.