Phase-Transfer-Catalyzed Asymmetric Conjugate Cyanation of Alkylidenemalonates with KCN in the Presence of a Brønsted Acid Additive

Highly enantioselective conjugate cyanation of alkylidenemalonates with KCN was achieved under mild phase-transfer conditions with a bifunctional phase-transfer catalyst. The effect of Brønsted acid additives was examined based on the hypothetical catalytic cycle, and the Brønsted acid additive was found to be essential to promote the conjugate cyanation efficiently.