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 (see scheme). The methodology was applied to the short total syntheses of bisabolane sesquiterpenes (S)-(+)-curcumene, (E)-(S)-(+)-3- dehydrocurcumene and (S)-(+)-tumerone. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.