SYNTHESIS OF PHENOXIDE-COORDINATED IRIDIUM(III) N-HETEROCYCLIC CARBENE COMPLEXES AND APPLICATION IN REDUCTIVE AMINATION REACTIONS
Project no. 462 · Status: Kapanmış · 2017
Summary
In the present study, a series of new o-aryloxide chelated [Ir(NHC)Cp*Cl] (NHC = N-heterocyclic carbene; Cp* = pentamethylcyclopentadienyl) complexes (2a-g) has been prepared by reaction of [IrCp*Cl2]2 with an in situ prepared NHC-Ag complex at ambient temperature. The IrIII complexes were stable towards air and moisture and were fully characterized by 1H, 13C NMR, HRMS, elemental analysis and single crystal X-ray diffraction. The new complexes were found to be active catalysts for transfer hydrogenative reductive amination under aqueous conditions with formate as hydrogen source at 50 °C. Among the complexes tested, o-naphthoxide chelated NHC-IrIII complex (2g) exhibited the highest catalytic activity for this reaction. Various carbonyl compounds including aliphatic and aromatic ketones and aldehydes reacted with amines to give corresponding amines with turnover numbers up to 490 (for ketones) and 14800 (for aldehydes). Keywords: N-heterocyclic carbene, iridium, reductive amination