Catalytic enantioselective Gilman-Speeter synthesis of β-lactams by nucleophilic activation of carboxylic acids

A novel Gilman-Speeter synthesis of β-lactams has been developed that was rendered highly enantioselective by virtue of isothiourea catalyst’s nucleophilicity. This process depends upon the HATU conversion of carboxylic acids to activated esters which then undergo attack by the homochiral catalyst and subsequently deprotonated by inorganic base to furnish catalytic quantities of the corresponding enolate ions that react with imines to provide the requisite β-lactams in good yields and enantiomeric excesses.