Selective Transfer Hydrogenation of C=O and Conjugated C=C Bonds Using An NHC‐Based Pincer (CNC)Mn^I Complex in Methanol**

Abstract

Base metal catalyzed transfer hydrogenation reactions using methanol is highly challenging. Employing a single N-heterocyclic carbene (NHC)-based pincer (CNC)Mn I complex, chemoselective single and double transfer hydrogenation of α, βunsaturated ketones to saturated ketones or alcohols by utilizing methanol as the hydrogen source is disclosed. The protocol was tolerant towards the selective transfer hydrogenation of C=C or C=O bonds in the presence of several other reducible functional groups and led to the synthesis of several biologically relevant molecules and natural products. Notably, this is the first report of a Mn-catalyzed transfer hydrogenation of carbonyl groups with methanol. Several control experiments, kinetic studies, Hammett studies, and density functional theory (DFT) calculations were carried out to understand the mechanistic details of this catalytic process.

Selectivity-controllable hydrogen transfer reduction of α,β-unsaturated aldehydes over high-entropy catalysts

“…In recent years, the hydrogen transfer reaction using aliphatic alcohols as hydrogen sources in place of hydrogen has been proposed as an efficient method of reduction of the unsaturated CC and CO double bonds of organic compounds. 15–18 Also, the modification of solid catalysts by means of alloying or selective poisoning can modulate the product selectivity of hydrogenation of unsaturated compounds. 19 It is found that, in the hydrogen transfer reaction of 5-hydroxymethyl furfural, noble metals such as Pd, Ru, and Rh preferentially undergo furan ring saturation to generate tetrahydrofuran-based products.…”