Direct Ruthenium‐Catalyzed Hydrogenation of Carboxylic Acids to Alcohols

Abstract

The "green" reduction of carboxylic acids to alcohols is a challenging task in organic chemistry. Herein, we describe a general protocol for generation of alcohols by catalytic hydrogenation of carboxylic acids. Key to success is the use of a combination of Ru(acac)3, triphos and Lewis acids. The novel method showed broad substrate tolerance and a variety of aliphatic carboxylic acids including biomass-derived compounds can be smoothly reduced.

TiO2‐Supported Re as a General and Chemoselective Heterogeneous Catalyst for Hydrogenation of Carboxylic Acids to Alcohols

“…Also, Beller et al. used Ru(acac) 3 (triphos) (acac=acetylacetonate) as a homogeneous catalyst in the presence of a Lewis acid to promote the selective hydrogenation for various carboxylic acids . Saito et al.…”

Synergetic Catalysis for One‐pot Bis‐alkoxycarbonylation of Terminal Alkynes over Pd/Xantphos−Al(OTf)3 Bi‐functional Catalytic System

“…Knowingly, the non‐coordinating ability of OTf − confers Al(OTf) 3 the Lewis super‐acidity . The synergetic activation of MeOH by Al(OTf) 3 upon Lewis‐acid pair interaction makes MeOH be an available hydride‐source …”

“…In the literature, metal triflates are powerful Lewis‐acid catalysts in organic synthesis in charge of activation of electron‐rich O‐atom (oxophilicity) in carbonyl group (−CO), hydroxyl (−OH) or epoxy ring . In addition, metal triflates also can serve as the co‐catalysts in transition metal catalyzed hydrogenation of carboxylic acids and alkoxycarbonylation of olefins . In comparison to Bronsted acids as the most typical hydride‐sources, metal triflates also can interact with proton‐donor like H 2 O or alcohol (usually as the nucleophilic reactants) to promote the formation of metal‐hydride intermediate, with advantages of low‐cost, no need of overdosage, less corrosion to equipment, and satisfactory robustness against hydrolysis .…”

An Improved Strategy for the Synthesis of Ethylene Glycol by Oxamate‐Mediated Catalytic Hydrogenation

“…Rapid industrialization in recent years, which has greatly increased the amounts of CO andC O 2 emitted into the atmosphere, is am ajor global concern. [16,17] Milstein and co-workersr eported ah ighly active ruthenium PNN pincer catalystf or ester and amide hydrogenation. Upgrading C1 feedstocks (for example, CO, CO/H 2 ,o rC O 2 )t hrough CÀCb ond formationi sa ne conomical and sustainable means of synthesizing bulk chemicals.…”

“…Over the past decade, progress in the development of highly efficient hydrogenation catalysts has greatly accelerated. [16,17] Milstein and co-workersr eported ah ighly active ruthenium PNN pincer catalystf or ester and amide hydrogenation. [16,17] Milstein and co-workersr eported ah ighly active ruthenium PNN pincer catalystf or ester and amide hydrogenation.…”