Halogenation process for preparing 2-(oxoazetidinyl)-3-chloromethyl-3-butenoate

摘要

A process for preparing an azetidinone derivative represented by the formula (I) <IMAGE> (I) wherein R1 represents an aryl group, arylmethyl group or aryloxymethyl group, R2 represents hydrogen atom or a carboxyl-protecting group and R3 represents an alkyl group or aryl group, the process comprising reacting an azetidinone derivative represented by the formula (II) <IMAGE> (II) wherein R1, R2 and R3 are as defined above with a chlorinating agent.