Phase-Transfer Organocatalyzed Asymmetric Vinylogous Mannich Reaction

Significance

Jørgensen and Niess report an efficient asymmetric vinylogous Mannich reaction of di­cyanoalkylidenes 1 with α-amido sulfones 2 as imine precursors in the presence of the phase-transfer catalyst 3. This can lead to Mannich products of ketones (formally) and N-Boc imines after oxidation of the initial products. The reaction works well with a range of α-amido sulfones 2 derived from aromatic and heteroaromatic aldehydes, and with a variety of cyclic and open-chain dicyanomethylene derivatives 1, to give access to aminoalkylated alkylidene compounds 4 in generally good yields and enantioselectivities. The use of non-cyclic dicyanoalkylidenes or dicyano­alkylidenes derived from cycloheptanone leads to a dramatic decrease in diastereoselectivity.