Phosphine‐Catalyzed β,γ‐Umpolung Domino Reaction of Allenic Esters: Facile Synthesis of Tetrahydrobenzofuranones Bearing a Chiral Tetrasubstituted Stereogenic Carbon Center
enantio‐, diastereo‐, regio‐, and chemoselective phosphine‐catalyzedβ,γ‐umpolungdominoreaction of allenicesters with dienones has been developed for the first time. The designed sequence, involving oxy‐Michael and Rauhut–Currier reactions, produced highly functionalized tetrahydrobenzofuranones, bearing a chiraltetrasubstitutedstereogeniccenter, in up to 96 % ee.
The acid–base organocatalyzed intramolecularRauhut–Currier (RC) reaction of the dienone enolates has been developed. The enantioselective RC process produces the highly functionalized α-methylidene-γ-butyrolactones as a single diastereomer with up to 98% ee.