Catalytic Asymmetric α-Alkylation of Ketones and Aldehydes with N-Benzylic Sulfonamides through Carbon-Nitrogen Bond Cleavage

A range of ketones and aldehydes smoothly undergo asymmetric S(N)1 alpha-alkylation with N-benzylic sulfonamides in the presence of 10 mol % of a chiral imidazolidinone and trifluoroacetic acid to give the corresponding products in good to excellent yields and with good enantioselectivity. This chemistry has been successfully extended to the asymmetric desymmetrization of 4-substituted cyclohexanones, which exhibits greater than 99:1 diastereoselectivity and good enantioselectivity.