Highly Functional Group Tolerant, (E)-Selective Transfer Semihydrogenation of Alkynes Catalysed by Iridium Complex Bearing Unsymmetrical Ferrocene-Based Phosphine Ligand

Abstract

Herein, we present (E)-selective transfer semihydrogenation of alkynes based on in situ generated iridium complex from [Ir(COD)Cl]2 and unsymmetrical ferrocene-based phosphine ligand in the presence of formic acid as a hydrogen donor. The catalytic system is distinguished by unprecedented chemoselectivity and exceptional stereoselectivity substantiated by the broad scope of test-ed substrates, including natural products derivatives. The uniform reaction conditions may be applied to various alkynes, owing to a lack of over-reduction. The intriguing difference in catalytic activity between unsymmetrical and symmetrical ferrocene-based ligands was attributed to diver-gent coordination and steric hindrance. The presented methodology constitutes a solution to the common limitations of the published catalytic systems.