N-Heterocyclic Carbene-Catalyzed Construction of 1,3,5-Trisubstituted Benzenes from Bromoenals and α-Cyano-β-methylenones.

A direct and efficient approach to 1,3,5-trisubstituted benzenes has been developed via N-heterocyclic carbene-catalyzed [2 + 4] annulation of α-bromoenals and α-cyano-β-methylenones. The reaction worked well for both aryl- and alkylenones.