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The homogeneously catalyzed Guerbet upgrading of ethanol to butanol can be modulated by the application of partial H2 pressure before the reaction. Ruthenium(II) PNP pincer complexes with methylene‐extended acridine‐based ligands and singly‐chelated ruthenium(II) complexes with PN ligands perform best at very low catalyst loadings and upon the application of catalyst‐specific pre‐reaction partial H2 pressure. The combination of ruthenium(II) PNP pincer complexes and manganese(I) pincer complexes with MACHO‐type PNP ligands allows for even lower ruthenium loadings while retaining low base load and consumption, thus enabling high space‐time yields, catalyst productivity and recyclability. Mechanistically, Mn is proposed to stabilize coordinatively unsaturated Ru species and allow coordination of ethoxide to Ru instead of attacking the electrophilic ligand backbone based on NMR spectroscopy and X‐ray crystallography. [ABSTRACT FROM AUTHOR]

Polyurethanes are synthesized on industrial scale by the reaction of diisocyanates with diols in the presence of catalysts which are commonly based on tin complexes and amines. However, due to the toxicity and volatility of these tin catalysts and amines, there is the need to develop new catalysts that are more environmentally benign. Herein, we report the synthesis of O^N^O pincer‐ligated Mn(III) and Fe(III) complexes that serve as suitable catalysts for urethane formation and are stable to hydrolysis as predicted by computations and observed experimentally. The O^N^O pincer scaffold is vital to the activity of these catalysts, simultaneously ensuring increased solubility in the reaction medium as well as providing a stable framework upon dissociation of co‐ligands in the catalytic cycle. In silico mechanistic investigations for urethane formation show that the stabilization of active species in square‐planar geometries enabled by these O^N^O ligands permit the simultaneous coordination of alcohol and isocyanate in suitable configuration at the metal center. [ABSTRACT FROM AUTHOR]

An organocatalytic route has been developed for the isomerization of exo‐vinylene carbonates (exo‐VCs) to endo‐vinylene carbonates (endo‐VCs). The exo‐VC starting material can easily be obtained from propargylic alcohols via cyclization with carbon dioxide. In this study, these exo‐VCs are shown to isomerize to the thermodynamically more stable endo‐VCs in the presence of an N‐heterocyclic base and phenol. Density functional theory (DFT) studies were conducted to elucidate the mechanism, tackling difficulties of the description of charge separation steps. This isomerization process delivers an ample diversity of endo‐VCs in good to excellent yields and chemoselectivities under mild reaction conditions. [ABSTRACT FROM AUTHOR]

Herein, a general applicable method for the atom‐economic catalytic construction of a broad range of 1,2‐dialkylaminoethers is presented. By taking advantage of an elaborated protocol for the photocatalyzed anti‐Markovnikov selective hydroamination of nonactivated alkenes, a series of 1,2‐dialkylaminoethers was accessed by reacting readily available vinyl ethers with secondary alkyl amines. It was demonstrated that the reaction can be performed at low catalyst loadings while the commonly employed triisopropylbenzene thiol Hydrogen Atom Transfer (HAT)‐catalyst was replaced by an easier accessible mesityl thiol. Furthermore, the inexpensive and readily available diphenyl disulfide was proven as suitable HAT‐catalyst alternative for the efficient hydroamination of simple vinyl ethers. [ABSTRACT FROM AUTHOR]

Anilides are often found in pharmaceuticals and active ingredients in crop protection. Although of great interest, the atom‐ and step economic formation of the amide bond between a less nucleophilic aniline with an acid or ester remains still a major challenge. Herein, we report an aminolysis of aromatic and alkyl esters with anilines catalyzed by a readily available catalytic system comprising of an earth‐abundant Mn‐salt in combination with an inexpensive base. [ABSTRACT FROM AUTHOR]

The influence of the ligand backbone on the enantioselectivity in the ruthenium‐catalyzed direct asymmetric reductive amination of acetophenone with NH3 and H2, using bidentate binaphthyl‐substituted phosphine ligands, was investigated in a combined computational and experimental study. A model for the bite angle dependence of the enantiomeric excess (ee) when using diphosphines bearing binaphthyl‐groups on the P‐atoms was developed. This revealed a significant potential for increasing the enantioselectivity, if ligands with a larger bite angle than the previously reported (S,S)‐f‐binaphane are used. Suitable backbone candidates were selected from more than one million structures provided by the Cambridge Structural Database (CCDC‐CSD) and the most promising candidates were synthesized accordingly. Despite all efforts, an increase of the ee was not possible with this approach. The larger backbones resulted in the preference of different ligand coordination modes avoiding the formation of the more strongly enantiodiscriminant substrate pocket between the naphthyl wings. [ABSTRACT FROM AUTHOR]

A copper(I)/phosphine system that homogeneously catalyses the alkynylation of formaldehyde with acetylene or terminal alkynes is reported. Using acetylene at atmospheric pressure, the catalyst consisting of <1 mol% copper(I) phenylacetylide and a trialkyl bisphosphine ligand shows a high selectivity towards the formation of propargyl alcohol rather than 1,4‐butynediol, which is not reported for common heterogeneous copper acetylide catalysts. The biphasic water/toluene reaction mixture allows the separation of targeted products with the aqueous layer and catalyst recycling via the organic layer. [ABSTRACT FROM AUTHOR]

SINCE World War II, American literature has repeatedly questioned the existence of social and religious meaning in a society capable of destroying itself. In Walker Percy's The Moviegoer, Binx Bolling, [...]

The hydrogenation of (+)‐Sclareolide to (−)‐ambradiol catalyzed by a manganese pincer complex is reported. The hydrogenation reaction is performed with an air‐ and moisture‐stable manganese catalyst and proceeds under relatively mild reaction conditions at low manganese and base loadings. A range of other esters could be successfully hydrogenated leading to the corresponding alcohols in good to quantitative yields using this easy‐to‐make catalyst. A scale‐up experiment was performed leading to 99.3 % of the isolated yield of (−)‐Ambradiol. [ABSTRACT FROM AUTHOR]

Chemical recycling, in particular hydrogenative depolymerization, offers a promising way to utilize plastic waste. This report covers the manganese‐catalyzed hydrogenation of polyurethane materials to the corresponding monomeric units. The key to success is a Mn pincer complex as a potent hydrogenation catalyst in combination with elevated temperatures (up to 200 °C) and appropriate solvents to ensure sufficient solubility of the polymers. A wide range of polyurethane samples of varying polyol and isocyanate compositions, some of which feature significant amounts of urea functionalities, are depolymerized, releasing polyetherols and diaminotoluene (TDA) in yields of up to 89 % and 76 %, respectively. [ABSTRACT FROM AUTHOR]