Chelation-Controlled Enantioselective Synthesis of Key Intermediates for the Preparation of Carbapenem Antibiotics PS-5 and 1β-Methyl-PS-5

Article abstract of DOI:10.1021/jo00252a025

Reaction of the E silyl ketene acetal derived from (1S,2R)-N-methylephedrine butyrate (7) with TiCl4 and β-alkoxy aldehyde 5 gave the aldol product in 75percent yield as a 78:11:11 mixture of stereoisomers.In agreement with a chelated transition structure