A New Phenoxide Chelated IrIII N-Heterocyclic Carbene Complex and Its Application in Reductive Amination Reactions

A new phenoxide chelated [Ir(NHC)Cp*Cl] (NHC = N-heterocyclic carbene; Cp* = pentamethylcyclopentadienyl) complex (3) has been prepared by reaction of [IrCp*Cl2]2 with an in situ prepared NHC-Ag complex in dichloromethane at ambient temperature. The IrIII complex was stable toward air and moisture and was fully characterized by 1H, 13C NMR, HRMS, and single-crystal X-ray diffraction. The new complex was found to be an active catalyst for transfer hydrogenative reductive amination under aqueous conditions with formate as hydrogen source as well as hydrogenative reductive amination reactions using H2. Various carbonyl compounds such as aliphatic and aromatic ketones and aldehydes were successfully reacted with amines to give new amines. In comparison with transfer hydrogenative reductive amination, the reductive amination with H2 is faster and permits higher molar ratios of the substrate to the catalyst (S/C). © 2015 American Chemical Society.Engineering and Physical Sciences Research Council, EPSRC Swansea Universit