An Adaptive Rhodium Catalyst to Control the Hydrogenation Network of Nitroarenes

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(36)

Published: June 27, 2022

An adaptive catalytic system that provides control over the nitroarene hydrogenation network to prepare a wide range of aniline and hydroxylamine derivatives is presented. This takes advantage delicate interplay between rhodium(III) center Lewis acidic borane introduced in secondary coordination sphere metal. The high chemoselectivity catalyst presence various potentially vulnerable functional groups its readiness be deployed at preparative scale illustrate practicality. Mechanistic studies density theory (DFT) methods were used shed light on mode functioning elucidate origin adaptivity. competition for interaction with boron solvent molecule substrate was found crucial When operating THF, reduction stops platform, whereas reaction can directed platform toluene.

Language: Английский

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Aluminium‐Catalyzed Selective Hydroboration of Esters and Epoxides to Alcohols: C−O Bond Activation

Chemistry - A European Journal, Journal Year: 2022, Volume and Issue: 29(4)

Published: Oct. 13, 2022

In this work, the molecular aluminium dihydride complex bearing an N, N'-chelated conjugated bis-guanidinate (CBG) ligand is used as a catalyst for reducing wide range of aryl and alkyl esters with good tolerance alkene (C=C), alkyne (C≡C), halides (Cl, Br, I F), nitrile (C≡N), nitro (NO2 ) functionalities. Further, we investigated catalytic application in C-O bond cleavage epoxides into corresponding branched Markovnikov ring-opening products. addition, chemoselective intermolecular reduction over other reducible functional groups, such amides alkenes, has been established. Intermediates are isolated characterized by NMR HRMS studies, which confirm probable cycles hydroboration epoxides.

Language: Английский

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Mild and Chemoselective Carboxylic Acid Reduction Promoted by Borane Catalysis

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(43)

Published: Sept. 1, 2022

Although considerable advances have been made in developing chemoselective transformations of ubiquitous carboxylic acid groups, many challenges still exist. For instance, their selective reduction is problematic if both more nucleophilic and electrophilic groups are present the starting material. Here, we address this problem with a simple mild protocol using bench-stable reagents at ambient temperatures. This platform able to tolerate diverse range functionality, leaving ketones, esters, nitro-groups, olefins, nitriles amides untouched. A combination experimental computational mechanistic experiments demonstrate that reaction proceeds via hidden borane catalysis small quantities situ generated BH

Language: Английский

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Aluminium‐Catalyzed Selective Reduction of Heteroallenes Through Hydroboration: Amide/Thioamide/Selenoamide Bond Construction and C=X (X=O, S, Se) Bond Activation**

European Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 2022(39)

Published: Sept. 12, 2022

Abstract An unprecedented conjugated bis‐guanidinate (CBG) stabilized aluminium dihydride, [LAlH 2 ; (L={(ArNH)(ArN)−C=N−C=(NAr)(NHAr)}; Ar=2,6‐Et ‐C 6 H 3 )] ( I ) catalyzed chemoselective hydroboration of heteroallenes such as carbodiimide (CDI)s, isocyanates, isothiocyanates, and isoselenocyanates is reported. A wide range heteroallenes, including electron‐donating withdrawing groups, experience to obtain selectively N‐boryl amide, N‐borylaminal, methyl amine products. More importantly, a single sustainable molecular aluminium‐based catalyst effectively catalyzes CDIs, into formamidines, formamides, thioformamides, selenoformamides, respectively. Further, heteroallene substrates undergo hydrodeoxygenation (HDO), hydrodesulfurization (HDS), hydrodeselenization (HDSe) reactions leading amines. In addition, series control kinetic experiments indicate that the hydride species are essential for all partial complete reduction steps breaking C=X (X=O, S, Se) bonds in heteroallenes.

Language: Английский

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Mild and Chemoselective Carboxylic Acid Reduction Promoted by Borane Catalysis

Angewandte Chemie, Journal Year: 2022, Volume and Issue: 134(43)

Published: Sept. 1, 2022

Abstract Although considerable advances have been made in developing chemoselective transformations of ubiquitous carboxylic acid groups, many challenges still exist. For instance, their selective reduction is problematic if both more nucleophilic and electrophilic groups are present the starting material. Here, we address this problem with a simple mild protocol using bench‐stable reagents at ambient temperatures. This platform able to tolerate diverse range functionality, leaving ketones, esters, nitro‐groups, olefins, nitriles amides untouched. A combination experimental computational mechanistic experiments demonstrate that reaction proceeds via hidden borane catalysis small quantities situ generated BH 3 playing key role exquisite selectivity observed.

Language: Английский

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Blue‐Light Enhanced Iron Catalysed Hydrosilylation of Carboxamides and Carboxylic Esters at Ambient Conditions

European Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 27(32)

Published: May 17, 2024

Abstract We report herein a blue‐light‐promoted iron‐catalyzed reduction of carboxamides and carboxylic esters. Conducting the reaction under hydrosilylation conditions blue light (2×24 W, 450–460 nm) in presence an iron(0) based pre‐catalyst, Fe(CO) 4 (IMes), amines alcohols were obtained, respectively, notably at ambient conditions, whereas using white light, higher temperatures up to 100 °C required. Preliminary mechanism studies highlighted crucial role not only generate catalytic active species, but also some steps cycle.

Language: Английский

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Alcohol Synthesis by Cobalt-Catalyzed Visible-Light-Driven Reductive Hydroformylation

Published: July 25, 2022

A cobalt-catalyzed reductive hydroformylation of terminal and 1,1-disubstituted alkenes is described. One-carbon homologated alcohols were synthe-sized directly from CO H2, affording anti-Markovnikov products (34–87% yield) with exclu-sive regiocontrol (linear/branch > 99:1) for mini-mally functionalized alkenes. Irradiation the air-stable cobalt hydride, (dcype)Co(CO)2H (dcype = dicyclohexylphosphinoethane) blue light gen-erated active catalyst that mediates alkene hy-droformylation subsequent aldehyde hydro-genation. Mechanistic origins absolute regiocon-trol investigated by in-situ monitoring tandem catalytic reaction using high-pressure mul-tinuclear NMR spectroscopy.

Language: Английский

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Ein adaptiver Rhodiumkatalysator zur Steuerung des Hydrierungsnetzwerks von Nitroarenen

Angewandte Chemie, Journal Year: 2022, Volume and Issue: 134(36)

Published: June 27, 2022

Abstract Es wird ein adaptives katalytisches System vorgestellt, das die Kontrolle über Nitroaren‐Hydrierungsnetzwerk zur Herstellung einer breiten Palette von Anilin‐ und Hydroxylaminderivaten ermöglicht. Dieses profitiert einem delikaten Zusammenspiel zwischen Rhodium(III)‐Zentrum Lewis‐sauren Boran, in sekundäre Koordinationssphäre des Metalls eingeführt wird. Die hohe Chemoselektivität Katalysators Anwesenheit verschiedener potenziell angreifbarer funktioneller Gruppen seine Bereitschaft, im präparativen Maßstab eingesetzt zu werden, veranschaulichen Praxistauglichkeit. Mechanistische Studien Methoden der Dichtefunktionaltheorie (DFT) wurden eingesetzt, um Funktionsweise untersuchen den Ursprung Adaptivität klären. Konkurrenz Lösungsmittelmolekül Substrat Wechselwirkung mit Bor erwies sich als entscheidend für Adaptivität. Bei Reaktion THF stoppt Reduktionsnetzwerk an Hydroxylamin‐Plattform, während Toluol auf Anilin‐Plattform gelenkt werden kann.

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