Catalytic asymmetric Staudinger reactions to form beta-lactams: an unanticipated dependence of diastereoselectivity on the choice of the nitrogen substituent.
There are relatively few methods for the catalytic asymmetric synthesis of beta-lactams, and those that have been reported are generally cis selective. This communication describes the first catalytic enantioselective Staudinger reactions that preferentially furnish trans beta-lactams (trans = relationship of Ph to R1). 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 beta-lactams readily react with nucleophiles to generate useful families of compounds, such as gamma-amino alcohols and beta-amino acids.
Lee
Elaine C
EC
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Hodous
Brian L
BL
Bergin
Enda
E
Shih
Crystal
C
Fu
Gregory C
GC
D002384:Catalysis; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D013237:Stereoisomerism; D047090:beta-Lactams / Q000138:chemical synthesis*
D047090:beta-Lactams; D009584:Nitrogen