Dai Z, Pan YM, Wang SG, Zhang X, Yin Q. Direct reductive amination of ketones with ammonium salt catalysed by Cp*Ir(III) complexes bearing an amidato ligand.
Org Biomol Chem 2021;
19:8934-8939. [PMID:
34636833 DOI:
10.1039/d1ob01710a]
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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.
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