PdCl_2-Catalyzed Efficient Transformation of Propargylic Amines to (E)-alpha-Chloroalkylidene-beta-lactams

摘要

The PdCl_2-catalyzed cyclocarbonylation reaction of propargylic amines with CuCl_2 and benzoquinone afforded (E)-alpha-chloroalkylidene-beta-lactams in moderate to good yields.The formation of the corresponding Z-isomers or five-membered products was not observed.The reaction of the readily available optically active propargylic amines provides a convenient synthesis of the corresponding (E)-alpha-chloroalkylidene-beta-lactams with high ee values.The structure and the stereochemistry of the products were established by the X-ray single-crystal diffraction study of (E)-6d and (E)-6e,which indicates that the stereoselectivity in this reaction is different from what was observed with propargylic alcohols.A rationale for this reaction was proposed.