Diastereo- and enantioselective direct vinylogous Michael addition of γ-substituted butenolides to 2-enoylpyridines catalyzed by chiral bifunctional amine-squaramides.

Abstract

The diastereo- and enantioselective direct vinylogous Michael addition reaction of γ-substituted butenolides to 2-enoylpyridines has been achieved. A range of γ,γ-disubstituted butenolide derivatives, bearing two consecutive tri- and tetrasubstituted stereogenic centers, were readily obtained in good yields with excellent stereoselectivities (up to >99 : 1 dr and >99% ee).