Chemoselective carbene insertion into the N-H bonds of NH3•H2O

The conversion of inexpensive aqueous ammonia (NH3 center dot H2O) into value-added primary amines by N-H insertion persists as a longstanding challenge in chemistry because of the tendency of Lewis basic ammonia (NH3) to bind and inhibit metal catalysts. Herein, we report a chemoselective carbene N-H insertion of NH3 center dot H2O using a TpBr3Ag-catalyzed two-phase system. Coordination by a homoscorpionate TpBr(3) ligand renders silver compatiblewithNH(3) and H2O 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.