Tandem cationic cyclisation-aziridinium ion formation-nucleophilic ring opening: new methodology for the stereocontrolled synthesis of substituted pyrrolidines

A novel tandem cationic cyclisation-aziridinium ion formation-nucleophilic ring opening procedure has been developed which provides powerful new metho dology for the stereocontrolled synthesis of a wide variety of substituted pyrrolidines from acyclic precursors. The intermediate bicyclic aziridinium ions can be isolated and their structure has been confirmed by X-ray cryst allography.