Methanol as Hydrogen Source: Transfer Hydrogenation of Aldehydes near Room Temperature

Abstract

A cyclometalated rhodium complex has been found to show excellent activity in dehydrogenation of methanol at room temperature. This feature allows for the catalytic transfer hydrogenation of various aldehydes with methanol as both hydrogen source and solvent under very mild conditions. A hydroxy functionality on the ligand is shown to be critical for this unusual activity.

N-Methylation of Amines with Methanol Catalyzed by Iridium(I) Complexes Bearing an N,O-Functionalized NHC Ligand

“…Anal. calcd for C 23 (10). A solution of 3 (50 mg, 0.085 mmol) in toluene/methanol 1:1 (5 mL) was treated with Cs 2 CO 3 (138 mg, 0.425 mmol) and stirred for 30 min at room temperature.…”

“…The reductive amination involving formic acid, formaldehyde, or carbon dioxide, and the use of dimethyl carbonate, , dimethyl sulfoxide (DMSO), CH 3 NO 2 , or Me 3 NBH 3 as methylating agents are more sustainable alternatives that have been intensively studied in the last decade. Nonetheless, some of them still suffer from low atom economy and require harsh reaction conditions or an excess of reducing agents. , Methanol has been actively investigated as a hydrogen source, C1 reagent for catalytic organic transformations, , and energy applications, and has emerged as a greener approach in the methylation of amines and nitroarene derivatives . In this regard, methanol is a convenient methyl source because it is less hazardous, cheap, and available from many plentiful sources, and it only produces water as a byproduct in the methylation processes.…”

Catalytic Base‐Free Transfer Hydrogenation of Biomass Derived Furanic Aldehydes with Bioalcohols and PNP Pincer Complexes

“…[%] [b] 1 Ru-3 (0. hazardous deuterated reducing reagents such as NaBD 4 or LiAlD 4 . [33] Therefore, our regioselective and straightforward TH method based on direct catalytic H/D exchange using Ru-4 and ethanol-d 6 as deuterium source is of high interest.…”

Recent Development in the Synthesis and Catalytic Application of Iridacycles

“…Notably, the analogous rhodacycles are active in methanol dehydrogenation even at room temperature, allowing for TH reactions with methanol as the hydrogen source. For example, a wide range of aromatic and aliphatic aldehydes were reduced to the corresponding alcohols with methanol as both the hydrogen source and solvent near room temperature (Scheme 41) [85,86] …”

“…For example, a wide range of aromatic and aliphatic aldehydes were reduced to the corresponding alcohols with methanol as both the hydrogen source and solvent near room temperature (Scheme 41). [85,86]…”