Cyanide-Catalyzed Cyclizations via Aldimine Coupling

Aldimine coupling (AIC) is the nitrogen analogue
of the benzoin condensation and has been applied to dialdimines, providing the first examples of cyclizations effected
by cyanide-catalyzed AIC. Sodium cyanide promoted the
facile, intramolecular cyclization of several dialdimines in
N,N-dimethylformamide, methanol, or methylene chloride/water (phase-transfer conditions) yielding a variety of six-membered heterocycles. Under aerobic conditions, an oxidative cyclization occurs to provide the diimine heterocycle.
Oligomerization was observed with rigid dialdimines for
which cyclization was precluded.