A novel synthetic approach to α-alkylidene-α-lactams

PdCl2-Catalyzed Efficient Transformation of Propargylic Amines to (E)-α-Chloroalkylidene-β-lactams

[reaction: see text] The PdCl2-catalyzed cyclocarbonylation reaction of propargylic amines with CuCl2 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.

Transformation of 4-Acetoxy-3-Vinylazetidin-2-Ones to 3-(1-Hydroxyethyl)Azetidin-2-Ones and 3-Ethylideneazetidin-2-Ones: Intermediates for Carbapenem Antibiotics

4-Acetoxy-3-vinylazetidin-2-one and 4-formyl-3-vinylazetidin-2-one are transformed to the carbapenem intermediates 4-acetoxy-3-(1-hydroxyethyl)azetidin-2-one and 4-acetoxy-3-ethylideneazetidin-2-one respectively, and the synthesis of a 6-vinylcarbapenem is reported.