Organocatalytic Asymmetric Vinylogous Michael Addition of Dicyanoolefins to Imine Intermediates Generated in situ from Arenesulfonylalkylindoles

An organocatalytic asymmetric vinylogous Michael addition of dicyanoolefins to vinylogous imine intermediates generated in situ from arenesulfonylalkylindoles has been developed. This protocol provides an easy and convenient approach to C-3 alkyl-substituted indole derivatives with high yields (up to 93%), diastereomeric ratios (up to 99:1 dr) and enantioselectivities (up to 99% ee). The resulting adducts can be also readily converted to pyrazolo derivatives or alpha-alkylation products of ketones without any decrease of the diastereoselectivities and enantioselectivities.