Catalytic Asymmetric Staudinger Reactions to Form β-Lactams: An Unanticipated Dependence of Diastereoselectivity on the Choice of the Nitrogen Substituent
journal contributionposted on 24.08.2005, 00:00 by Elaine C. Lee, Brian L. Hodous, Enda Bergin, Crystal Shih, Gregory C. Fu
There are relatively few methods for the catalytic asymmetric synthesis of β-lactams, and those that have been reported are generally cis selective. This communication describes the first catalytic enantioselective Staudinger reactions that preferentially furnish trans β-lactams (trans = relationship of Ph to R). The key to this method is the use of an N-triflyl protecting group for the imine. Along with serving as interesting targets in their own right, N-triflyl β-lactams readily react with nucleophiles to generate useful families of compounds, such as γ-amino alcohols and β-amino acids.