Iron-Catalyzed Methylation Using the Borrowing Hydrogen Approach

ACS Catalysis, Journal Year: 2018, Volume and Issue: 8(7), P. 6440 - 6445

Published: June 14, 2018

A general iron-catalyzed methylation has been developed using methanol as a C1 building block. This borrowing hydrogen approach employs Knölker-type (cyclopentadienone)iron carbonyl complex catalyst (2 mol %) and exhibits broad reaction scope. variety of ketones, indoles, oxindoles, amines, sulfonamides undergo mono- or dimethylation in excellent isolated yields (>60 examples, 79% average yield).

Language: Английский

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Isoelectronic Manganese and Iron Hydrogenation/Dehydrogenation Catalysts: Similarities and Divergences

Accounts of Chemical Research, Journal Year: 2018, Volume and Issue: 51(6), P. 1558 - 1569

Published: June 4, 2018

ConspectusSustainable processes that utilize nontoxic, readily available, and inexpensive starting materials for organic synthesis constitute a major objective in modern chemical research. In this context, it is highly important to perform reactions under catalytic conditions replace precious metal catalysts by earth-abundant nonprecious catalysts. particular, iron manganese are promising candidates, as these among the most abundant metals earth's crust, inexpensive, exhibit low environmental impact. As far concerned, hydrogenations acceptorless alcohol dehydrogenation (AAD), sometimes conjunction with hydrogen autotransfer reactions, becoming areas of While first very synthetic process representing atom-efficient clean methodology, AAD an oxidant-free, environmentally benign reaction where carbonyl compounds together dihydrogen valuable product and/or reactant (autotransfer) water formed. Carbonyl compounds, typically generated situ, can be converted into other useful such amines, imines, or heterocycles.In 2016 several groups, including ours, discovered time potential hydride biscarbonyl Mn(I) complexes bearing strongly bound PNP pincer ligands related tridentate effective versatile hydrogenation, transfer reactions. These isoelectronic analogues respective monocarbonyl Fe(II) display similar reactivities but also quite divergent behavior depending on coligands. Moreover, show improved long-term stability high robustness toward harsh conditions. light recent achievements, Account contrasts catalysts, highlighting specific features connected particular structural electronic properties. It addresses opportunities restrictions their applications. Apart from classical hydrogenations, covers developments resulting complex molecules heterocycles via multicomponent The ambivalent hydrogen-based redox chemistry provides access variety synthetically reductive oxidative coupling Hence, cover broad scope applications activities productivities competitive those well-established knowledge about nature characteristics active Mn(I)- Fe(II)-based systems paves way conceptually mechanistically well-founded research, which might lead further discovery novel extending current limitations reactivity. underlines base beginning challenge contributes advancement waste-free sustainable catalysis.

Language: Английский

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Homogeneous manganese-catalyzed hydrogenation and dehydrogenation reactions

Chem, Journal Year: 2020, Volume and Issue: 7(5), P. 1180 - 1223

Published: Dec. 9, 2020

Language: Английский

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General synthesis of primary amines via reductive amination employing a reusable nickel catalyst

Nature Catalysis, Journal Year: 2018, Volume and Issue: 2(1), P. 71 - 77

Published: Dec. 3, 2018

Language: Английский

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Chiral Tridentate Ligands in Transition Metal-Catalyzed Asymmetric Hydrogenation

Chemical Reviews, Journal Year: 2021, Volume and Issue: 121(13), P. 7530 - 7567

Published: May 20, 2021

Asymmetric hydrogenation (AH) of double bonds has been one the most effective methods for preparation chiral molecules and synthesis important building blocks. In past 60 years, noble metals with bidentate ligands have shown marvelous reactivity enantioselectivity in asymmetric a series prochiral substrates. recent developing tridentate played an increasingly role AH. With modular frameworks variety functionalities on side arms, ligand complexes enable both reactivities stereoselectivities. Although great achievements made metal catalysts since 1990s, design earth abundant still high demand. This review summarizes development homogeneous hydrogenation. The philosophy reaction mechanisms are highlighted discussed as well.

Language: Английский

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Lutidine‐Based Chiral Pincer Manganese Catalysts for Enantioselective Hydrogenation of Ketones

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(15), P. 4973 - 4977

Published: Feb. 18, 2019

A series of MnI complexes containing lutidine-based chiral pincer ligands with modular and tunable structures has been developed. The complex shows unprecedentedly high activities (up to 9800 TON; TON=turnover number), broad substrate scope (81 examples), good functional-group tolerance, excellent enantioselectivities (85-98 % ee) in the hydrogenation various ketones. These aspects are rare earth-abundant metal catalyzed hydrogenations. utility protocol have demonstrated asymmetric synthesis a variety key intermediates for drugs. Preliminary mechanistic investigations indicate that an outer-sphere mode substrate-catalyst interactions probably dominates catalysis.

Language: Английский

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Cobalt Complexes as an Emerging Class of Catalysts for Homogeneous Hydrogenations

Accounts of Chemical Research, Journal Year: 2018, Volume and Issue: 51(8), P. 1858 - 1869

Published: Aug. 9, 2018

ConspectusCatalytic hydrogenation using molecular hydrogen represents a green and practical approach for reductions of all kinds organic chemicals. Traditionally, in the majority these processes presence transition metal catalysts is required. In this regard, noble-metal-based have largely been implemented, such as application iridium, palladium, rhodium, ruthenium, others. Recently, employment earth-abundant 3d metals has emerged to replace utilization scarce noble because their availability, lower cost, often reduced toxicity. respect, several cobalt complexes, form either molecularly well-defined or situ-formed are receiving increasing attention from scientific community. Importantly, stability reactivity complexes greatly supported by multidentate ligands under steric and/or electronic influences. For instance, tridentate tetradentate phosphine indirectly tune center accelerate overall process, whereas direct participation ligand pincer-type through ligand–metal cooperation regulates elementary steps catalytic cycle.In Account, we emphasize specifically advancements cobalt-catalyzed hydrogenations accomplished our group. A variety substrate classes ranging simple molecules (e.g., carbon dioxide) complex compounds were explored mild efficient conditions. Notable examples include reduction dioxide afford formates Co(BF4)2·6H2O/Tetraphos catalyst system methanol employing Co(acac)3/Triphos HNTf2. As interesting synthesis fine chemicals, cobalt-promoted nitriles primary amines reductive alkylations indoles carboxylic acids alkylating agents highlighted. Moreover, highly selective N-heteroarenes additive-free conditions possible specific complexes. More recently, set esters could be hydrogenated corresponding alcohols with high efficiency use cobalt–PNP pincer catalyst. particular, decent enabled selectivity functional group tolerance achieved. Throughout studies, it was found that pairing suitable precursor an appropriate plays crucial role harnessing desired reactivity, while other monodentate bidentate showed no investigations. Our developments provide supervisory information future exploration reactions types involving catalysis. Furthermore, relevant contributions groups, remaining challenges, perspectives research area also presented.

Language: Английский

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Manganese-Catalyzed α-Alkylation of Ketones, Esters, and Amides Using Alcohols

ACS Catalysis, Journal Year: 2018, Volume and Issue: 8(11), P. 10300 - 10305

Published: Oct. 2, 2018

Herein we report the manganese-catalyzed C–C bond-forming reactions via α-alkylation of ketones, amides, and esters, using primary alcohols. β-Alkylation secondary alcohols by to obtain α-alkylated ketones is also reported. The are catalyzed a (iPr-PNP)Mn(H)(CO)2 pincer complex under mild conditions in presence (catalytic) base liberating water (and H2 case alcohol alkylation) as sole byproduct.

Language: Английский

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Manganese-Catalyzed and Base-Switchable Synthesis of Amines or Imines via Borrowing Hydrogen or Dehydrogenative Condensation

ACS Catalysis, Journal Year: 2018, Volume and Issue: 8(9), P. 8525 - 8530

Published: Aug. 8, 2018

The use of earth-abundant transition metals as a noble metal replacement in catalysis is especially interesting if different catalytic reactivity observed. We report, here, on the selective manganese-catalyzed base-switchable synthesis N-alkylated amines or imines. In both reactions, borrowing hydrogen/hydrogen autotransfer (N-alkyl amine formation) dehydrogenative condensation (imine formation), we start from same and alcohols Mn precatalyst. key presence potassium base to prefer N-alkylation sodium permit imine formation. Both bases react with manganese hydride via deprotonation. manganate reacts about 40 times faster an give corresponding than hydride. selectivity seems unique for complexes. observe broad scope complete product overlap, all alcohol combinations can be converted into N-alkyl imine, good functional group tolerance.

Language: Английский

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Cobalt–Pincer Complexes in Catalysis

Chemistry - A European Journal, Journal Year: 2018, Volume and Issue: 25(1), P. 122 - 143

Published: Sept. 5, 2018

Abstract Non‐noble metal catalysts based on pincer type compounds are of special interest for organometallic chemistry and organic synthesis. Next to iron manganese, currently cobalt–pincer complexes successfully applied in various catalytic reactions. In this review the recent progress (de)hydrogenation, transfer hydrogenation, hydroboration hydrosilylation as well dehydrogenative coupling reactions using is summarised.

Language: Английский

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