Ruthenium(ii) complexes with N-heterocyclic carbene–phosphine ligands for the N-alkylation of amines with alcohols

Organic & Biomolecular Chemistry, Год журнала: 2021, Номер 19(15), С. 3451 - 3461

Опубликована: Янв. 1, 2021

A Ru catalyst with the hetero-bidentate NHC-phosphine ligand, which realizes N-alkylation of amines alcohols improved catalytic activity.

Язык: Английский

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Well-Defined Bis(NHC)Mn(I) Complex Catalyzed Tandem Transformation of α,β-Unsaturated Ketones to α-Methylated Ketones Using Methanol

ACS Catalysis, Год журнала: 2022, Номер 12(19), С. 12444 - 12457

Опубликована: Сен. 28, 2022

Tandem transformation of α,β-unsaturated ketones to α-methylated by utilizing methanol as both the hydrogen and C1 sources is reported in presence a phosphine-free bis-N-heterocyclic carbene-Mn(I) (bis-NHC-Mn(I)) catalyst. The dehydrogenative coupling between produces corresponding along with 1 equiv formaldehyde water. Among different bis-NHC-Mn(I) complexes, ethyl wingtip-substituted complex triflate counteranion showed highest catalytic activity. This system was highly effective for reductive methylation wide variety substrates including aromatic, heteroaromatic, aliphatic straight chains containing ketones. Notably, this methodology led synthesis pharmaceutically important drug molecules such eperisone lanperisone. Several control experiments, kinetic studies, Hammett density functional theory (DFT) calculations were carried out understand tandem process.

Язык: Английский

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Recent Advances for Alkylation of Ketones and Secondary Alcohols Using Alcohols in Homogeneous Catalysis

Advanced Synthesis & Catalysis, Год журнала: 2022, Номер 364(18), С. 3100 - 3121

Опубликована: Июль 4, 2022

Abstract The alkylation of ketones or secondary alcohols using as alkylating agents via hydrogen borrowing strategy presents a powerful method for the synthesis ɑ‐alkylated ketones. In this review, we summarize progress catalyzed by Ir, Pd, Rh, Ru, Mn, Fe, Co, Ni, and Cu catalysts α‐alkylation with cross‐coupling from 2017 to 2021. A wide range (aromatic aliphatic ketones) (benzylic primary alcohols, aromatic alkenyl diols) are well tolerated. Furthermore, also discuss current challenges propose perspectives on coming development in filed. objective present review is give an overview recent advances β‐alkylation alcohols. Finally, hope that will inspirations magnified image

Язык: Английский

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Bis(N‐Heterocyclic Carbene) Manganese(I) Complexes: Efficient and Simple Hydrogenation Catalysts

Angewandte Chemie International Edition, Год журнала: 2023, Номер 62(35)

Опубликована: Июль 3, 2023

The use of bis(NHC) manganese(I) complexes 3 as catalysts for the hydrogenation esters was investigated. For that purpose, a series has been synthesized via an improved two step procedure utilizing bis(NHC)-BEt3 adducts. By applying with KHBEt3 additive, various aromatic and aliphatic were hydrogenated successfully at mild temperatures low catalyst loadings, highlighting efficiency novel catalytic system. versatility developed system further demonstrated by other substrate classes like ketones, nitriles, N-heteroarenes alkenes. Mechanistic experiments DFT calculations indicate inner sphere mechanism loss one CO ligand reveal role BEt3 cocatalyst.

Язык: Английский

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Surmounting Alkoxide Trap Strategy: N-Heterocyclic Carbene Chromium(0)-Catalyzed C-Alkylation between Alcohols

ACS Catalysis, Год журнала: 2023, Номер 13(19), С. 12481 - 12493

Опубликована: Сен. 8, 2023

The crucial role of the alkoxide trap problem and impact oxidation state chromium center were demonstrated on catalytic activity due to d-wall issue. Through strategy surmounting trap, a Cr(0) catalyst was presented herein for efficient C-alkylation between alcohols via borrowing hydrogen/hydrogen autotransfer. synthesized bis-(N-heterocyclic carbene)-Cr(0) system shows an performance (40 examples, up 96% yield). Only loading cheap readily available base NaOH is effective enough reaction. Compared with Cr(III)/Cr(II), can well avoid d-p π interaction in key metal-alkoxide intermediate, thus overcoming thermodynamic sink problem. It plausible that Cr(III) systems need be reduced Cr(II) weakening effect enhancing by using reductive strong bases. This should helpful development nonprecious transition metal catalysts.

Язык: Английский

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NNN manganese complex-catalyzed α-alkylation of methyl ketones using alcohols: an experimental and computational study

Dalton Transactions, Год журнала: 2024, Номер 53(7), С. 3236 - 3243

Опубликована: Янв. 1, 2024

A quinoline-based pincer Mn catalyst for α-alkylation of methyl ketones using primary alcohols as alkyl surrogates is presented. The C–C bond formation reaction proceeds via a hydrogen auto-transfer protocol, generating water the only by-product.

Язык: Английский

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Impact of the Methylene Bridge Substitution in Chelating NHC‐Phosphine Mn(I) Catalyst for Ketone Hydrogenation

Chemistry - A European Journal, Год журнала: 2024, Номер 30(22)

Опубликована: Фев. 7, 2024

Abstract Systematic modification of the chelating NHC‐phosphine ligand (NHC = N ‐heterocyclic carbene) in highly efficient ketone hydrogenation Mn(I) catalyst fac ‐[(Ph 2 PCH NHC)Mn(CO) 3 Br] has been performed and catalytic activity resulting complexes was evaluated using acetophenone as a benchmark substrate. While variation phosphine NHC moieties led to inferior results than for parent system, incorporation phenyl substituent into methylene bridge improved performance by ca . times providing maximal TON values range 15000–20000. Mechanistic investigation combining experimental computational studies allowed rationalize this beneficial effect an enhanced stabilization reaction intermediates including anionic hydride species PC(Ph)NHC)Mn(CO) H] − playing crucial role process. These highlight interest such carbon substitution strategy being rarely employed design chemically non‐innocent ligands.

Язык: Английский

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A Proton‐Responsive Pyridyl(benzamide)‐Functionalized NHC Ligand on Ir Complex for Alkylation of Ketones and Secondary Alcohols

Chemistry - A European Journal, Год журнала: 2021, Номер 27(41), С. 10737 - 10748

Опубликована: Май 17, 2021

Abstract A Cp*Ir(III) complex ( 1 ) of a newly designed ligand L featuring proton‐responsive pyridyl(benzamide) appended on N ‐ heterocyclic carbene (NHC) has been synthesized. The molecular structure reveals dearomatized form the ligand. protonation with HBF 4 in tetrahydrofuran gives corresponding aromatized [Cp*Ir(L H)Cl]BF 2 ). Both compounds are characterized spectroscopically and by X‐ray crystallography. acid is examined H NMR UV‐vis spectra. character exploited for catalyzing α ‐alkylation ketones β secondary alcohols using primary as alkylating agents through hydrogen‐borrowing methodology. Compound an effective catalyst these reactions exhibits superior activity comparison to structurally similar iridium )Cl]PF 6 3 lacking pendant amide moiety. catalytic alkylation wide substrate scope, low base loadings, short reaction time. efficacy also demonstrated syntheses quinoline lactone derivatives via acceptorless dehydrogenation, selective two steroids, pregnenolone testosterone. Detailed mechanistic investigations DFT calculations substantiate role process.

Язык: Английский

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Well‐Defined Ni−SNS Complex Catalysed Borrowing Hydrogenative α‐Alkylation of Ketones and Dehydrogenative Synthesis of Quinolines

Advanced Synthesis & Catalysis, Год журнала: 2022, Номер 364(14), С. 2429 - 2437

Опубликована: Май 23, 2022

Abstract The “borrowing hydrogen” (BH) method for C‐alkylation reactions using alcohol as alkylating agents is an important synthetic transformation. In this respect, designing cheap and bench stable earth abundant metal catalyst borrowing hydrogen transformation a key challenge to be witnessed. Herein we have presented synthesis of non‐phosphine, easily accessible SNS−Ni complexes. Ni‐catalyst was successfully applied the ketone enolates α‐alkylated ketones. Primary with different functional groups various heteroaromatic alcohols are well tolerated. present system efficiently gram scale also green chemistry metrics reaction were calculated. protocol extended biologically quinoline moieties. Finally, control experiments deuterium labelled suggest that proceeds via pathway. magnified image

Язык: Английский

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Decoding the CO₂ Reduction Mechanism of a Highly Active Organometallic Manganese Electrocatalyst: Direct Observation of a Hydride Intermediate and Its Implications

ACS Catalysis, Год журнала: 2023, Номер 13(15), С. 10375 - 10385

Опубликована: Июль 25, 2023

A detailed mechanistic study of the electrochemical CO2 reduction catalyzed by fac-[MnI(CO)3(bis-MeNHC)MeCN]+ complex (1-MeCN+) is reported herein combining in situ FTIR spectroelectrochemistry (SEC), synthesis and characterization catalytic intermediates, DFT calculations. Under low proton concentrations, 1-MeCN+ efficiently catalyzes electroreduction with long catalyst durability selectivity toward CO (ca. 100%). The [Mn-I(CO)3(bis-MeNHC)]− anion (1–) tetracarbonyl [MnI(CO)4(bis-MeNHC)]+ (1-CO+) are key intermediates CO2-to-CO mechanism due to their impact on reaction rate, respectively. Increasing concentration increases formate production (up 15% FE), although remains major product. origin ascribed competitive protonation 1– form a Mn(I) hydride (1-H), detected SEC absence CO2. 1-H was also synthesized thoroughly characterized, including X-ray diffraction analysis. Stoichiometric reactivity studies labeled 13CO2 indicate fast formation corresponding neutral species (1-OCOH) at room temperature. modeling confirms intrinsic capability undergo transfer strong σ-donor properties bis-MeNHC moiety. However, large potential required for HCOO– release from 1-OCOH limits overall CO2-to-HCOO– cycle. Moreover, experimentally observed preferential over dictated shallow kinetic barrier binding compared Mn–H bond formation. highlights potential, pKa, hydricity metal intermediate as crucial factors affecting CO2RR molecular systems.

Язык: Английский

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