A highly enantioselective and regioselective organocatalytic direct Mannich reaction of methyl alkyl ketones with cyclic imines benzo[e][1,2,3]-oxathiazine 2,2-dioxides

A highly enantioselective direct Mannich reaction of methyl alkyl ketones with cyclic imines benzo[e][1,2,3] oxathiazine 2,2-dioxides, catalyzed by the combination of cinchona alkaloid derived primary amine and TFA, is disclosed. For unsymmetrical methyl alkyl ketones, it is favoured that specific regioselective addition to the imine substrates occurs at the less-substituted methyl group by steric control.