γ-Alkylation of α-Branched Enals with Stable Carbocations

Significance

The asymmetric vinylogous γ-alkyl­ation of α-branched enals with bis-(4-dimethyl­aminophenyl)-methanol is reported. The catalyst involves cinchona alkaloid derived primary amine 1, in combination with chiral phosphoric acid 2, setting the stage for a cooperative mechanism. The catalyst salt formed between 1 and one equivalent of chiral phosphoric acids, is believed to deliver a dienamine, which reacts with the benz-hydryl cation through a highly ordered transition state.