Chemoselective carbene insertion into the N-H bonds of NH·HO.

The conversion of inexpensive aqueous ammonia (NH·HO) into value-added primary amines by N-H insertion persists as a longstanding challenge in chemistry because of the tendency of Lewis basic ammonia (NH) to bind and inhibit metal catalysts. Herein, we report a chemoselective carbene N-H insertion of NH·HO using a TpAg-catalyzed two-phase system. Coordination by a homoscorpionate Tp ligand renders silver compatible with NH and HO and enables the generation of electrophilic silver carbene. Water promotes subsequent [1,2]-proton shift to generate N-H insertion products with high chemoselectivity. The result of the reaction is the coupling of an inorganic nitrogen source with either diazo compounds or N-triftosylhydrazones to produce useful primary amines. Further investigations elucidate the reaction mechanism and the origin of chemoselectivity.