Asymmetric Synthesis of trans and cis β-Lactams

Article abstract of DOI:10.1016/0040-4039(95)00772-5

The condensation of doubly deprotonated triphenylglycol propionate 4a and imines 1 leads to the formation of trans β-lactams 5 in a diastereoselective and enantioselective manner (85 to > 97percent e.e.).On the other hand, the lithium enolates of the propionates 4b,c, derived from triphenylglycol as well, afford predominantly cis 2-azetidinones 6 in 87 to > 97percent e.e.