Cobalt-Catalyzed Hydrosilylation of Carbon Dioxide to the Formic Acid, Formaldehyde, and Methanol Level─How to Control the Catalytic Network?

JACS Au, Journal Year: 2021, Volume and Issue: 1(11), P. 2058 - 2069

Published: Oct. 4, 2021

The selective hydrosilylation of carbon dioxide (CO2) to either the formic acid, formaldehyde, or methanol level using a molecular cobalt(II) triazine complex can be controlled based on reaction parameters such as temperature, CO2 pressure, and concentration. Here, we rationalize catalytic mechanism that enables arrival at each product platform. Key reactive intermediates were prepared spectroscopically characterized, while energy profile analyzed with density functional theory (DFT) methods microkinetic modeling. It transpired stepwise reduction involves three consecutive cycles, including same cobalt(I) hydride active species. increasing kinetic barriers associated step competing transfer steps in cycles corroborate strong influence catalyst environment selectivity. fundamental mechanistic insights provide consistent description system rationalize, particular, experimentally verified opportunity steer toward formaldehyde chemically most challenging level.

Language: Английский

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Aminotriazole Mn(I) Complexes as Effective Catalysts for Transfer Hydrogenation of Ketones

ChemCatChem, Journal Year: 2018, Volume and Issue: 10(20), P. 4514 - 4518

Published: Sept. 16, 2018

Abstract A catalytic system based on complexes comprising abundant and cheap manganese together with readily available aminotriazole ligands is reported. The new Mn(I) are catalytically competent in transfer hydrogenation of ketones 2‐propanol as hydrogen source. reaction proceeds under mild conditions at 80 °C for 20 h 3 % catalyst loading using either KO t Bu or NaOH base. Good to excellent yields were obtained a wide substrate scope broad functional group tolerance. results by varying the substitution pattern ligand consistent an out‐sphere mechanism H‐transfer.

Language: Английский

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Facile reduction of carboxylic acids to primary alcohols under catalyst-free and solvent-free conditions

Chemical Communications, Journal Year: 2018, Volume and Issue: 55(10), P. 1386 - 1389

Published: Dec. 21, 2018

We report the development of a facile protocol for deoxygenative hydroboration aliphatic and aryl carboxylic acids to afford corresponding primary alcohols under solvent-free catalyst-free conditions. The reaction proceeds ambient temperature exhibits good tolerance towards various functional groups generates quantitative yields. plausible mechanism involves formation Lewis acid-base adducts as well liberation hydrogen gas.

Language: Английский

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Efficient Cobalt Catalyst for Ambient-Temperature Nitrile Dihydroboration, the Elucidation of a Chelate-Assisted Borylation Mechanism, and a New Synthetic Route to Amides

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(38), P. 15327 - 15337

Published: Aug. 28, 2019

N,N-Diborylamines have emerged as promising reagents in organic synthesis; however, their efficient preparation and full synthetic utility yet to be realized. To address both shortcomings, an effective catalyst for nitrile dihydroboration was sought. Heating CoCl2 the presence of PyEtPDI afforded six-coordinate Co(II) salt, [(PyEtPDI)CoCl][Cl]. Upon adding 2 equiv NaEt3BH, hydride transfer one chelate imine functionality observed, resulting formation (κ4-N,N,N,N-PyEtIPCHMeNEtPy)Co. Single-crystal X-ray diffraction density functional theory calculations revealed that this compound possesses a low-spin ground state featuring antiferromagnetic coupling singly reduced imino(pyridine) moiety. Importantly, (κ4-N,N,N,N-PyEtIPCHMeNEtPy)Co found catalyze nitriles using HBPin with turnover frequencies up 380 h–1 at ambient temperature. Stoichiometric addition experiments adds across Co–Namide bond generate intermediate can react additional or nitriles. Computational evaluation reaction coordinate B–H insertion steps occur on antiferromagnetically coupled triplet spin manifold. Interestingly, borylimine following BPin from borylated arm regenerate Borylimine reduction is turn facile follows same ligand-assisted borylation pathway. The independent hydroboration alkyl aryl imines also demonstrated 25 °C. With series N,N-diborylamines hand, carboxylic acids allowed direct synthesis amides 120 °C, without need exogenous reagent.

Language: Английский

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Reduction of Cyclic and Linear Organic Carbonates Using a Readily Available Magnesium Catalyst

ACS Catalysis, Journal Year: 2019, Volume and Issue: 9(12), P. 11634 - 11639

Published: Nov. 20, 2019

Efficient reduction of cyclic and linear organic carbonates catalyzed by a readily available earth alkaline catalyst has been achieved. The described homogenous reaction based on ligand-free magnesium provides an indirect route for the conversion CO2 into valuable alcohols. proceeds with high yields under mild conditions, low loading short times, shows broad applicability toward various carbonates. Additionally, it can be applied depolymerization polycarbonates.

Language: Английский

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