Reusable Gold(I) Catalysts with Unique Regioselectivity for Intermolecular Hydroamination of Alkynes

Two gold(I) phosphine complexes bearing the low-coordinating bis(trifluoromethanesulfonyl)imidate ligand, namely AuSPhosNTf(2) and AuPPh3NTf2, are active catalysts for the regioselective intermolecular hydroamination of both internal and terminal alkynes under mild reaction conditions. The catalysts show a regioselectivity based on electronic rather than steric factors, which allow the preferential synthesis of regioisomers opposite to those described previously. This subtle chemo- and regioselectivity depends on the catalyst, substrates and reaction conditions employed, and allows one to perform new tandem reactions. These gold(I) complexes operate under free-solvent conditions, without exclusion of air, without addition of acidic promoters and can be quantitatively recovered and reused by simple precipitation in hexane.