Direct reductive amination of ketones with ammonium salt catalysed by Cp*Ir(iii) complexes bearing an amidato ligand

Abstract

A series of half-sandwich Ir(III) complexes 1–6 bearing an amidato bidentate ligand were conveniently synthesized and applied to the catalytic Leuckart–Wallach reaction to produce racemic α-chiral primary amines. With 0.1 mol% of complex 1, a broad range of ketones, including aryl ketones, dialkyl ketones, cyclic ketones, α-keto acids, α-keto esters and diketones, could be transformed to their corresponding primary amines with moderate to excellent yields (40%–95%). Asymmetric transformation was also attempted with chiral Ir complexes 3–6, and 16% ee of the desired primary amine was obtained. Despite the unsatisfactory enantio-control achieved so far, the current exploration might stimulate more efforts towards the discovery of better chiral catalysts for this challenging but important transformation.