Au(I)–N-heterocyclic carbene complex-catalyzed synthesis of 1-substituted benzo[b][1,4]diazepines from N-substituted o-phenylenediamines and terminal alkynes

1-Substituted benzo[b][1,4]diazepines which are difficult to synthesize by traditional methods have been prepared by an Au(I)–N-heterocyclic carbene complex-catalyzed tandem hydroamination/cyclization process. This protocol features the one-pot formation of a seven-membered N-heterocycle via atom-economic hydroamination/cyclization reactions of readily available N-substituted o-phenylenediamines and terminal alkynes. Based on this strategy, fused tricyclic benzo[b][1,4]diazepines have been accessed for the first time.