Iridium-catalyzed efficient reduction of ketones in water with formic acid as a hydride donor at low catalyst loading

Abstract

Simple and functionalized ketones are readily reduced in water with very low catalyst loading using formic acid as a hydride donor.

Reduction of Aldehydes with Formic acid in Ethanol using Immobilized Iridium Nanoparticles on a Triazine‐phosphanimine Polymeric Organic Support

“…A reaction mechanism for the reduction of aldehydes in the presence of INP-TPA-POP was proposed according to the literature as shown in Scheme 5. [35][36][37][38] Accordingly, the formate anion can coordinate with catalyst metal center (II) to form iridium hydride (III) by evaluation of carbon dioxide. [39] In this situation, the formed Ir-hydride centers can trap aldehyde to transfer the hydride to the carbon of carbonyl group probably via a four-member ring transition state.…”

pH-Dependent transfer hydrogenation or dihydrogen release catalyzed by a [(η6-arene)RuCl(κ2-N,N-dmobpy)]+ complex: a DFT mechanistic understanding

“…[4][5][6][7][8] However, due to environmental and ecological advantages and reaction-specic pH selectivity, using water as the solvent for the TH of ketones is very convenient and attractive compared to traditional organic solvents. [9][10][11][12] Two hydrogen sources have primarily been used in TM-catalyzed TH, namely isopropanol and formic acid. The conception of metalligand bifunctional cooperation is oen used to explain the reaction mechanism of TH and the HH of polar double bonds catalyzed by TM complexes with different ligand environments such as diphosphine-diamine ruthenium catalyst A (see Scheme 1) [13][14][15][16][17][18][19] as well as those of TH using formic acid hydrogen sources.…”

“…A number of TH reactions of polar double bonds catalyzed by cyclometallated TM complexes have been developed in the past decades. 11,[24][25][26][27] Most of the TM catalysts for ketone/imine hydrogenation have a Lewis acidic site in the TM center and a Lewis basic site in the ligand moiety of the structure (TM-LB catalyst) or a Lewis basic site in the TM center and a Lewis acidic site in the ligand moiety (TM-LA catalyst). 2,28 In 1986, Shvo et al reported a useful TH catalyst (B in Scheme 2) for ketones, which is an example of a ligand-metal bifunctional catalyst wherein the redox activity is distributed between the metal center and a cyclopentadienone ligand.…”

“…In general, the dihydrogen release pathway, driven by the cyclometallated TM single-site system, is more favorable than the hydride transfer pathway under strongly acidic conditions, which is in agreement with the experimental results. 11,25 Compared with that of the H 1 atom of H 5 O 2 + and H 7 O 3 + , the H 1 atom in H 3 O + carries a more positive charge (see Table S1 in ESI †). This means that H 3 O + is more acidity.…”

A New and Eco‐Friendly Method for Reduction of Ketones in Water

“…have achieved reduction of some ketones in water with formic acid. In their study, they have demonstrated that TH reduction rates of some ketones are dependent on the pH values and catalyst TC‐7 (Iridium catalyst) have behaved best at pH=1.5, resulting in an 88% conversion . Yang et al.…”