Ruthenium(II) and rhodium(III) catalyzed asymmetric transfer hydrogenation (ATH) of acetophenone in isopropanol and in aqueous sodium formate using new chiral substituted aromatic monosulfonamide ligands derived from (1R,2R)-diaminocyclohexane

Computational Prediction of Chiral Iron Complexes for Asymmetric Transfer Hydrogenation of Pyruvic Acid to Lactic Acid

Density functional theory calculations reveal a formic acid-assisted proton transfer mechanism for asymmetric transfer hydrogenation of pyruvic acid catalyzed by a chiral Fe complex, FeH[(R,R)-BESNCH(Ph)CH(Ph)NH2](η6-p-cymene), with formic acid as the hydrogen provider. The rate-determining step is the hydride transfer from formate anion to Fe for the formation and dissociation of CO2 with a total free energy barrier of 28.0 kcal mol-1. A series of new bifunctional iron complexes with η6-p-cymene replaced by different arene and sulfonyl groups were built and computationally screened as potential catalysts. Among the proposed complexes, we found 1g with η6-p-cymene replaced by 4-isopropyl biphenyl had the lowest free energy barrier of 26.2 kcal mol-1 and excellent chiral selectivity of 98.5% ee.

Palladium/zinc co-catalyzed asymmetric transfer hydrogenation of oxabenzonorbornadienes with alcohols as hydrogen sources

Asymmetric transfer hydrogenation of oxabenzonorbornadienes was realized by using alcohols as hydrogen sources under a co-catalytic system of palladium and zinc.

Preparation of Pd-Loaded Hierarchical FAU Membranes and Testing in Acetophenone Hydrogenation

Pd-loaded hierarchical FAU (Pd-FAU) membranes, containing an intrinsic secondary non-zeolitic (meso)porosity, were prepared and tested in the catalytic transfer hydrogenation of acetophenone (AP) to produce phenylethanol (PE), an industrially relevant product. The best operating conditions were preliminarily identified by testing different solvents and organic hydrogen donors in a batch hydrogenation process where micron-sized FAU seeds were employed as catalyst support. Water as solvent and formic acid as hydrogen source resulted to be the best choice in terms of conversion for the catalytic hydrogenation of AP, providing the basis for the design of a green and sustainable process. The best experimental conditions were selected and applied to the Pd-loaded FAU membrane finding enhanced catalytic performance such as a five-fold higher productivity than with the unsupported Pd-FAU crystals (11.0 vs. 2.2 mg_product g_cat⁻¹·h⁻¹). The catalytic performance of the membrane on the alumina support was also tested in a tangential flow system obtaining a productivity higher than that of the batch system (22.0 vs. 11.0 mg_product g_cat⁻¹·h⁻¹).

Aqueous biphasic iron-catalyzed asymmetric transfer hydrogenation of aromatic ketones

For the first time, an iron(ii) catalyst is used in the biphasic asymmetric transfer hydrogenation (ATH) of ketones to enantioenriched alcohols employing water and potassium formate as the proton and hydride source, respectively.

Half-sandwich Ru(η6-C6H6) complexes with chiral aroylthioureas for enhanced asymmetric transfer hydrogenation of ketones – experimental and theoretical studies

The efficiency of Ru–benzene complexes towards ATH of ketones was studied.

Synthesis of imine and reduced imine compounds containing aromatic sulfonamide: use as catalyst for in situ generation of ruthenium catalysts in transfer hydrogenation of acetophenone derivatives

Three imine and three reduced imine ligands containing aromatic sulfonamide (2-7) were isolated by a simple method and characterized by FT-IR, NMR, and elemental analysis. Meanwhile, the interaction of 2-7 ligands with [(p-cymene)RuCl2]2 was analyzed in situ by UV-vis spectrophotometer. The in situ generated catalytic system derived from N-(2-(benzylideneamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides and N-(2-(benzylamino)phenyl)-2,4,6-trimethyl-benzenesulfonamides with [(p-cymene)RuCl2]2 was used as a catalyst in the transfer hydrogenation (TH) of p-substituted acetophenone derivatives. The catalytic systems displayed high activities, which increased in the order 7<4<5<6<1<2<3. The best activity for the TH of 4-chloroacetophenone was provided with the [(p-cymene)RuCl2]2/ligand (3) catalytic system (turnover frequency values: 720 h(-1) for 10 min on S/C: 500/1).

The N-H functional group in organometallic catalysis

The organometallic approach is one of the most active topics in catalysis. The application of NH functionality in organometallic catalysis has become an important and attractive concept in catalyst design. NH moieties in the modifiers of organometallic catalysts have been shown to have various beneficial functions in catalysis by molecular recognition through hydrogen bonding to give catalyst-substrate, ligand-ligand, ligand-catalyst, and catalyst-catalyst interactions. This Review summarizes recent progress in the development of the organometallic catalysts based on the concept of cooperative catalysis by focusing on the NH moiety.

Chemically engineered papain as artificial formate dehydrogenase for NAD(P)H regeneration

Organometallic complexes of the general formula [(η(6)-arene)Ru(N⁁N)Cl](+) and [(η(5)-Cp*)Rh(N⁁N)Cl](+) where N⁁N is a 2,2'-dipyridylamine (DPA) derivative carrying a thiol-targeted maleimide group, 2,2'-bispyridyl (bpy), 1,10-phenanthroline (phen) or ethylenediamine (en) and arene is benzene, 2-chloro-N-[2-(phenyl)ethyl]acetamide or p-cymene were identified as catalysts for the stereoselective reduction of the enzyme cofactors NAD(P)(+) into NAD(P)H with formate as a hydride donor. A thorough comparison of their effectiveness towards NAD(+) (expressed as TOF) revealed that the Rh(III) complexes were much more potent catalysts than the Ru(II) complexes. Within the Ru(II) complex series, both the N⁁N and arene ligands forming the coordination sphere had a noticeable influence on the activity of the complexes. Covalent anchoring of the maleimide-functionalized Ru(II) and Rh(III) complexes to the cysteine endoproteinase papain yielded hybrid metalloproteins, some of them displaying formate dehydrogenase activity with potentially interesting kinetic parameters.