Regioselective Synthesis of 3-Benzazepinones and Unexpected 5-Bromo-3-benzazepinones

Lei Zhang, Deju Ye, Yu Zhou, Guannan Liu, Enguang Feng, Hualiang Jiang, and Hong Liu

A regioselective hydroamidation of 2-(1-alkynyl)phenylacetamides with Au(PPh3)Cl/AgSbF6 as
the catalyst proceeded by a 7-endo-dig pathway to afford 3-benzazepinones. This method accommodates
a broad range of alkyl and aryl alkynyl substitutes in moderate to high yields (63-91%).
Moreover, unexpectedly, we also discovered a gold-mediated transformation from 2-(1-alkynyl)-
phenylacetamides to 5-bromo-3-benzazepinones, and AuBr3 was found to not only play an activation
role but also act as a reactant in the reaction for the first time.