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Ethers are of fundamental importance in organic chemistry and they are an integral part of valuable flavors, fragrances, and numerous bioactive compounds. In general, the reduction of esters constitutes the most straightforward preparation of ethers. Unfortunately, this transformation requires large amounts of metal hydrides. Presented herein is a bifunctional catalyst system, consisting of Ru/phosphine complex and aluminum triflate, which allows selective synthesis of ethers by hydrogenation of esters or carboxylic acids. Different lactones were reduced in good yields to the desired products. Even challenging aromatic and aliphatic esters were reduced to the desired products. Notably, the in situ formed catalyst can be reused several times without any significant loss of activity., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Aromatic ketones are enantioseletively hydrogenated in alcohols containing [RuX{(S,S)-Tsdpen}(eta(6)-p-cymene)] (Tsdpen=TsNCH(C(6)H(5))CH(C(6)H(5))NH(2); X=TfO, Cl) as precatalysts. The corresponding Ru hydride (X=H) acts as a reducing species. The solution structures and complete spectral assignment of these complexes have been determined using 2D NMR ((1)H-(1)H DQF-COSY, (1)H-(13)C HMQC, (1)H-(15)N HSQC, and (1)H-(19)F HOESY). Depending on the nature of the solvents and conditions, the precatalysts exist as a covalently bound complex, tight ion pair of [Ru(+)(Tsdpen)(cymene)] and X(-), solvent-separated ion pair, or discrete free ions. Solvent effects on the NH(2) chemical shifts of the Ru complexes and the hydrodynamic radius and volume of the Ru(+) and TfO(-) ions elucidate the process of precatalyst activation for hydrogenation. Most notably, the Ru triflate possessing a high ionizability, substantiated by cyclic voltammetry, exists in alcoholic solvents largely as a solvent-separated ion pair and/or free ions. Accordingly, its diffusion-derived data in CD(3)OD reflect the independent motion of [Ru(+)(Tsdpen)(cymene)] and TfO(-). In CDCl(3), the complex largely retains the covalent structure showing similar diffusion data for the cation and anion. The Ru triflate and chloride show similar but distinct solution behavior in various solvents. Conductivity measurements and catalytic behavior demonstrate that both complexes ionize in CH(3)OH to generate a common [Ru(+)(Tsdpen)(cymene)] and X(-), although the extent is significantly greater for X=TfO(-). The activation of [RuX(Tsdpen)(cymene)] during catalytic hydrogenation in alcoholic solvent occurs by simple ionization to generate [Ru(+)(Tsdpen)(cymene)]. The catalytic activity is thus significantly influenced by the reaction conditions.

An efficient and halogen-free catalytic methodology for the synthesis of β-amino alcohols from aromatic amines and biomass-derived carbohydrates is demonstrated for the first time. The activation of C5/C6 sugars by a ruthenium catalyst selectively generates the C2 alkylating reagent glycolaldehyde. The transformation involves metal-catalyzed hydrogen borrowing for the reduction of the imine intermediate. A series of arylamines bearing various substituents were successfully transformed into the desired products in good to excellent yields. [ABSTRACT FROM AUTHOR]

Abstract: Hydrogen is of fundamental importance for the construction of modern clean‐energy supply systems. In this context, the catalytic dehydrogenation of formic acid (FA) is a convenient method to generate H2 gas from an easily available liquid. One of the issues associated with current catalytic dehydrogenation systems is insufficient stability. Here, we present a robust and recyclable system for FA dehydrogenation by combining a ruthenium 1,1,1‐tris(diphenylphosphinomethyl)ethane complex and aluminum trifluoromethanesulfonate (Al(OTf)3). This robust system allows steady H2 production under pressure and recycling for an additional 14 runs without any apparent loss of activity (turnover frequencies up to 1920 h−1, turnover numbers up to 20 000). Notably, the catalyst can also be used for the dehydrogenation of formates and the reverse hydrogenation of bicarbonates and CO2. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Ethers are of fundamental importance in organic chemistry and they are an integral part of valuable flavors, fragrances, and numerous bioactive compounds. In general, the reduction of esters constitutes the most straightforward preparation of ethers. Unfortunately, this transformation requires large amounts of metal hydrides. Presented herein is a bifunctional catalyst system, consisting of Ru/phosphine complex and aluminum triflate, which allows selective synthesis of ethers by hydrogenation of esters or carboxylic acids. Different lactones were reduced in good yields to the desired products. Even challenging aromatic and aliphatic esters were reduced to the desired products. Notably, the in situ formed catalyst can be reused several times without any significant loss of activity. [ABSTRACT FROM AUTHOR]

Formation of C-C bonds from CO2 is a much sought after reaction in organic synthesis. To date, other than C-H carboxylations using stoichiometric amounts of metals, base, or organometallic reagents, little is known about C-C bond formation. In fact, to the best of our knowledge no catalytic methylation of C-H bonds using CO2 and H2 has been reported. Described herein is the combination of CO2 and H2 for efficient methylation of carbon nucleophiles such as indoles, pyrroles, and electron-rich arenes. Comparison experiments which employ paraformaldehyde show similar reactivity for the CO2/H2 system. [ABSTRACT FROM AUTHOR]

Formation of C-C bonds from CO2 is a much sought after reaction in organic synthesis. To date, other than C-H carboxylations using stoichiometric amounts of metals, base, or organometallic reagents, little is known about C-C bond formation. In fact, to the best of our knowledge no catalytic methylation of C-H bonds using CO2 and H2 has been reported. Described herein is the combination of CO2 and H2 for efficient methylation of carbon nucleophiles such as indoles, pyrroles, and electron-rich arenes. Comparison experiments which employ paraformaldehyde show similar reactivity for the CO2/H2 system. [ABSTRACT FROM AUTHOR]

Formation of C-C bonds from CO2 is a much sought after reaction in organic synthesis. To date, other than C-H carboxylations using stoichiometric amounts of metals, base, or organometallic reagents, little is known about C-C bond formation. In fact, to the best of our knowledge no catalytic methylation of C-H bonds using CO2 and H2 has been reported. Described herein is the combination of CO2 and H2 for efficient methylation of carbon nucleophiles such as indoles, pyrroles, and electron-rich arenes. Comparison experiments which employ paraformaldehyde show similar reactivity for the CO2/H2 system. [ABSTRACT FROM AUTHOR]

Formation of C-C bonds from CO2 is a much sought after reaction in organic synthesis. To date, other than C-H carboxylations using stoichiometric amounts of metals, base, or organometallic reagents, little is known about C-C bond formation. In fact, to the best of our knowledge no catalytic methylation of C-H bonds using CO2 and H2 has been reported. Described herein is the combination of CO2 and H2 for efficient methylation of carbon nucleophiles such as indoles, pyrroles, and electron-rich arenes. Comparison experiments which employ paraformaldehyde show similar reactivity for the CO2/H2 system. [ABSTRACT FROM AUTHOR]

The authors focus on the methylation of amines with carbon dioxide and hydrogen molecule (H2). They mention that two catalysts formed from ruthenium acetylacetonate [Ru(acac)3] and 1,1,1-tris(diphenylphosphinomethyl) ethane, enabled the conversion of carbon dioxide and carboxylic acid derivatives into N,N-dimethylaniline and N-methylaniline. They mention that methylation reaction with formamide and methanol formed intermediates, which then reduced to a methylated product.

The authors focus on the methylation of amines with carbon dioxide and hydrogen molecule (H2). They mention that two catalysts formed from ruthenium acetylacetonate [Ru(acac)3] and 1,1,1-tris(diphenylphosphinomethyl) ethane, enabled the conversion of carbon dioxide and carboxylic acid derivatives into N,N-dimethylaniline and N-methylaniline. They mention that methylation reaction with formamide and methanol formed intermediates, which then reduced to a methylated product.

Kohlendioxid kann zur selektiven reduktiven Methylierung sekundärer und primärer aromatischer und aliphatischer Amine verwendet werden. Vielfältige tertiäre Amine werden durch Einwirkung von CO2 und käuflichen Silanen in hohen Ausbeuten erhalten. Die Katalysereaktion toleriert Nitril ‐ , Olefin ‐ , Ether ‐ , Ester ‐ und Hydroxygruppen in den Substraten. [ABSTRACT FROM AUTHOR]

On the way to a green carbon cycle: Ding and co‐workers developed the highly efficient catalyst 1 for the hydrogenation of cyclic carbonates to diols and methanol (TON up to 87 000) by modification of the industrially applied omega process. [ABSTRACT FROM AUTHOR]

• P/N-H ligand facilitates Ru to exhibit efficient hydrogenation under CO. • The NH effect of ligands promote the hydrogenation process. • Co/Ru- L1 system smoothly achieves alcohol production under hydroformylation conditions. Efficient hydrogenation of aldehydes is highly desirable in hydroformylation process to obtain alcohol products. This work developed carbazole-derived phosphine ligands for efficient Ru-catalyzed hydrogenation of aldehydes in the presence of carbon monoxide. Up to 99 % yields of alcohols were obtained in the presence of high-pressure CO at 130 ℃. The results of different ligands revealed the crucial role of N H moiety on carbazole in promoting the catalytic hydrogenation. It was applied to the Co/Ru-catalyzed hydroformylation process, resulting in the production of long-chain alcohols with excellent yields. [Display omitted] [ABSTRACT FROM AUTHOR]