Intramolecular hydroamination catalysed by Ag complexes stabilised in situ by bidentate ligands

A series of silver complexes generated in situ from AgOSO2CF3 (AgOTf) and a range of bidentate ligands were investigated as catalysts for the intramolecular hydroamination of 4-pentyn-1-amine. A variety of P- and N-donor ligands were tested including the novel pyrazole-phosphine ligand 1-(2-(diphenylphosphino)phenyl)pyrazole. The best catalyst was formed from equimolar amounts of the P,N-donor ligand 1-(2-(diphenylphosphino)ethyl)pyrazole and AgOTf, which achieved a turnover rate of 129 h−1 for the cyclisation of 4-pentyn-1-amine.