Aminocatalytic enantioselective 1,6 additions of alkyl thiols to cyclic dienones: vinylogous iminium ion activation.

Remote transmission: In the presence of chiral amines, 2,4-dienones are activated toward the attack of a nucleophile at the δ position, a mode of activation that is termed vinylogous iminium ion catalysis. Specifically, the 1,6 addition of alkyl thiols to β-substituted cyclic dienones was catalyzed by a cinchona-based primary amine; the reaction was highly stereoselective and displayed high selectivity for reaction at the δ position.