SELECTIVE SYNTHESIS OF OPTICALLY-ACTIVE 3-HALOAZETIDIN-2-ONES OR AZIRIDINES BY THE CONDENSATION OF VARIOUS METAL ENOLATES OF ALPHA-HALOACETATE WITH A CHIRAL IMINE

Reaction products and their diastereofacial selectivity in the condensation of the ester enolates of alpha-haloacetate with a chiral imine possessing 1,3-dioxolane ring derived from (2S,3S)-1,4-dimethoxy-2,3-butanediol as a chiral auxiliary can be fully controlled by the metal enolate used; i.e., (3R,4R)-3-haloazetidine-2-one is obtained stereoselectively by the use of the triisopropoxytitanium enolates, while condensation with the lithium or zinc enolates provides (2R,3S)- or (2S,3R)-aziridine, respectively.