Isothiourea-catalyzed asymmetric synthesis of β-lactams and β-amino esters from arylacetic acid derivatives and N-sulfonylaldimines

This work is supported by a Royal Society for a University Research Fellowship and the EPSRC and GSK (Case Award) as well as by the European Research Council under the European Unionʼs Seventh Framework Programme (FP7/2007-2013) (ERC Grant Agreement No.279850)The isothiourea HBTM-2.1 (5 mol %) catalyzes the asymmetric formal [2 + 2] cycloaddition of both arylacetic acids (following activation with tosyl chloride) and preformed 2-arylacetic anhydrides with N-sulfonylaldimines, generating stereodefined 2,3-diaryl-β-amino esters (after ring-opening) and 3,4-diaryl-anti-β-lactams, respectively, with high diastereocontrol (up to >95:5 dr) and good to excellent enantiocontrol. Deprotection of the N-tosyl substituent within the β-lactam framework was possible without racemization by treatment with SmI2.PostprintPeer reviewe