Asymmetric construction of enantioenriched spiro gem-diamines via [3 + 3] annulation of α,β-unsaturated N-sulfonyl ketimines and 3-aminobenzofurans

Abstract

A general and facile catalytic asymmetric protocol for the construction of enantioenriched spiro gem-diamines through [3 + 3] annulation of α,β-unsaturated N-sulfonyl ketimines and 3-aminobenzofurans has been accomplished under the catalysis of bifunctional organocatalysts. In this reaction, α,β-unsaturated N-sulfonyl ketimines acted as dielectrophiles, and 3-aminobenzofurans acted as 1,3-C,N-dinucleophiles. Excellent yields, exclusive diastereoselectivities, high enantioselectivities, and a wide substrate scope were obtained in this efficient organocatalytic reaction.