Catalytic Enantioselective β‐Alkylation of α,β‐Unsaturated Aldehydes by Combination of Transition‐Metal‐ and Aminocatalysis: Total Synthesis of Bisabolane Sesquiterpenes

Abstract

Branching out! The first co-catalytic enantioselective (up to 98:2 e.r.) β-alkylation of α,β-unsaturated aldehydes by combination of simple chiral amine and copper catalysts provides β-branched aldehydes in a one-pot protocol. The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3-dehydrocurcumene and (S)-(+)-tumerone.