Synthesis of an Ir complex with functionalized N-heterocyclic carbene ligand for stereoselective reduction of ketone

Abstract

Recently, we succeed in developing hydroxy-amide-functionalized azolium compound as N-heterocyclic carbene (NHC) precursor. Now, a new NHC-Ir complex was synthesized by using the azolium salt derived from chiral .beta.-aminoalcohol. Azolium salt was converted into the NHC-Ag complex, which subsequently reacted with [IrCp*Cl₂]₂ to form the NHC-Ir complex whose structure was characterized by X-ray crystallographic studies. The Ir complex thus obtained catalyzed asymmetric transfer hydrogenation of acetophenone by 2-propanol to give the corresponding sec-alcohol in 60% ee.