Enantioselective benzoin condensation catalyzed by spirocyclic terpene-based N-heterocyclic carbenes

The synthesis of new chiral spirocyclic triazolium salts, derived from (1S)-fenchone and (1R)-camphorquinone, are described. These salts, which are N-heterocyclic carbene precatalysts, were successfully employed in the catalytic asymmetric benzoin condensation affording acyloins with good yields and moderate enantioselectivities.