3d Transition Metals for C–H Activation

Chemical Reviews, Journal Year: 2018, Volume and Issue: 119(4), P. 2192 - 2452

Published: Nov. 27, 2018

C–H activation has surfaced as an increasingly powerful tool for molecular sciences, with notable applications to material crop protection, drug discovery, and pharmaceutical industries, among others. Despite major advances, the vast majority of these functionalizations required precious 4d or 5d transition metal catalysts. Given cost-effective sustainable nature earth-abundant first row metals, development less toxic, inexpensive 3d catalysts gained considerable recent momentum a significantly more environmentally-benign economically-attractive alternative. Herein, we provide comprehensive overview on until summer 2018.

Language: Английский

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A comprehensive overview of directing groups applied in metal-catalysed C–H functionalisation chemistry

Chemical Society Reviews, Journal Year: 2018, Volume and Issue: 47(17), P. 6603 - 6743

Published: Jan. 1, 2018

The present review is devoted to summarizing the recent advances (2015-2017) in field of metal-catalysed group-directed C-H functionalisation. In order clearly showcase molecular diversity that can now be accessed by means directed functionalisation, whole organized following directing groups installed on a substrate. Its aim comprehensive reference work, where specific group easily found, together with transformations which have been carried out it. Hence, primary format this schemes accompanied concise explanatory text, are ordered sections according their chemical structure. feature typical substrates used, products obtained as well required reaction conditions. Importantly, each example commented respect most important positive features and drawbacks, aspects such selectivity, substrate scope, conditions, removal, greenness. targeted readership both experts functionalisation chemistry (to provide overview progress made last years) and, even more so, all organic chemists who want introduce way thinking for design straightforward, efficient step-economic synthetic routes towards molecules interest them. Accordingly, should particular also scientists from industrial R&D sector. overall goal promote application reactions outside research dedicated method development establishing it valuable archetype contemporary R&D, comparable role cross-coupling play date.

Language: Английский

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Inert C–H Bond Transformations Enabled by Organometallic Manganese Catalysis

Accounts of Chemical Research, Journal Year: 2018, Volume and Issue: 51(3), P. 816 - 827

Published: Feb. 14, 2018

ConspectusTraditional organic synthesis relies heavily on the transformations of various preinstalled functional groups, such as cross-coupling reactions using organohalides and organometallic reagents. The strategy C–H activation enables direct formation C–C/C–X (X = heteroatom) bonds from inert bonds, which can enhance atom- step-economy synthesis. To date, precious metals have overwhelmingly dominated field; however, rarity high cost these necessitate development more sustainable catalysts. In this regard, catalysts based manganese are highly desirable owing to abundant reserve in earth's crust its economic benefits, low toxicity, potentially unique reactivity. Although first stoichiometric manganese-mediated reaction was reported early 1970, manganese-catalyzed largely underdeveloped. How construct an efficient catalytic cycle for remains a key issue be addressed.In Account, we summarize our recent advances bonds. overcome challenges associated with building manganese-based cycles, developed two novel strategies, namely, synergy between bases (with or w/o bases) acids. By implementing former strategy, cooperative manganese/base systems that facilitate new mode bond by via redox-neutral base-assisted deprotonation mechanism. As such, requirement tedious preparation MnR(CO)5 complexes (R Me, Bn, Ph) eliminated, series arenes partners having C≡C C═C were achieved. Through latter acids, disclosed "dual activation" performing transformations, is, merging C–X multiple Lewis Consequently, scope substrates could expanded include challenging ketones olefinic compounds. Additionally, range significantly broadened those bearing polarized C═O, C═N, C≡N aldehydes, imines, nitriles. Remarkably, innate reactivity different reversed catalysis, even carried out at room temperature. Our findings provide guiding information future beyond. Related important contributions other groups mentioned, remaining perspective emerging area also presented.

Language: Английский

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Solvent‐Dependent Asymmetric Synthesis of Alkynyl and Monofluoroalkenyl Isoindolinones by CpRh^III‐Catalyzed C−H Activation

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(15), P. 4048 - 4052

Published: March 7, 2018

Abstract The asymmetric synthesis of alkynyl and monofluoroalkenyl isoindolinones from N‐methoxy benzamides α,α‐difluoromethylene alkynes is enabled by C−H activation with a chiral CpRh III catalyst. Remarkably, product formation solvent‐dependent; are afforded in MeOH (up to 86 % yield, 99.6 ee ) whereas generated i PrCN 98:2 Z / E , 93 ). Mechanistic studies revealed allene ‐configured alkenyl rhodium species as reaction intermediates. latter transformed into the corresponding monofluoroalkene upon protonation system an alkyne unusual anti β‐F elimination system. Notably, kinetic resolution processes occur this reaction. Despite moderate enantiocontrol for allene, ‐monofluoroalkenyl were obtained good enantiopurities one or two sequential processes.

Language: Английский

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Redox‐Neutral Manganese(I)‐Catalyzed C−H Activation: Traceless Directing Group Enabled Regioselective Annulation

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(41), P. 12778 - 12782

Published: Aug. 15, 2017

Abstract A strategy is reported in which traceless directing groups (TDGs) are used to promote the redox‐neutral Mn I ‐catalyzed regioselective synthesis of N‐heterocycles. Alkyne coupling partners bearing a group, serves as both chelator and internal oxidant, were control regioselectivity annulation reactions. This operationally simple approach highly effective with previously challenging unsymmetrical alkyne systems, including unbiased dialkyl alkynes, perfect regioselectivity. The conditions ability carry out on gram scale underscore usefulness this method. application concise bioactive compound PK11209 pharmaceutical moxaverine also described.

Language: Английский

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Methylenecyclopropane Annulation by Manganese(I)‐Catalyzed Stereoselective C−H/C−C Activation

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(32), P. 9415 - 9419

Published: June 12, 2017

Abstract C−H/C−C functionalizations with methylenecyclopropanes (MCPs) were accomplished a versatile base‐metal catalyst. A robust manganese(I) complex enabled the expedient annulation of MCPs by synthetically meaningful ketimines to deliver, upon one‐pot hydroarylation, densely substituted polycylic anilines in step‐economical fashion. Mechanistic studies provided strong support for facile organometallic C−H manganation, while typical cobalt, ruthenium, rhodium, and palladium catalysts found completely ineffective.

Language: Английский

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Manganese(I)‐Catalyzed Regio‐ and Stereoselective 1,2‐Diheteroarylation of Allenes: Combination of C−H Activation and Smiles Rearrangement

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(33), P. 9939 - 9943

Published: June 20, 2017

Abstract Heteroarenes are important structural motif in functional molecules. A Mn I ‐catalyzed 1,2‐diheteroarylation of allenes via a C−H activation/Smiles rearrangement cascade is presented. The reaction occurred under additive‐free or even solvent‐free conditions, which allowed the creation two C−C and one C−N bonds single operation. series structurally diverse bicyclic tricyclic compounds bearing an exocyclic double bond were constructed good to excellent efficiency. decarboxylative ring‐opening products led facile synthesis vicinal biheteroaryls. Synthetic applications demonstrated preliminary mechanistic studies conducted.

Language: Английский

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Organocatalytic Enantioselective Synthesis of Chiral Allenes: Remote Asymmetric 1,8‐Addition of Indole Imine Methides

Angewandte Chemie International Edition, Journal Year: 2020, Volume and Issue: 59(39), P. 17049 - 17054

Published: June 18, 2020

An organocatalytic enantioconvergent synthesis of chiral tetrasubstituted allenes is disclosed. With suitable phosphoric acid catalysts, a range racemic indole-substituted propargylic alcohols reacted with nucleophiles to provide efficient access series enantioenriched high enantioselectivities. Control experiments suggested mechanism involving remotely controlled asymmetric 1,8-addition the in situ generated indole imine methide via bifunctional transition state.

Language: Английский

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Dichotomy of Manganese Catalysis via Organometallic or Radical Mechanism: Stereodivergent Hydrosilylation of Alkynes

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 57(4), P. 923 - 928

Published: Dec. 5, 2017

Herein, we disclose the first manganese-catalyzed hydrosilylation of alkynes featuring diverse selectivities. The highly selective formation E-products was achieved by using mononuclear MnBr(CO)5 with arsenic ligand, AsPh3 . Whereas dinuclear catalyst Mn2 (CO)10 and LPO (dilauroyl peroxide) enabled reversed generation Z-products in good to excellent stereo- regioselectivity. Such a way controlling reaction stereoselectivity is unprecedented. Mechanistic experiments revealed dichotomy manganese catalysis via organometallic radical pathways operating E- Z-selective routes, respectively.

Language: Английский

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Synergistic Manganese(I) C−H Activation Catalysis in Continuous Flow: Chemoselective Hydroarylation

Angewandte Chemie International Edition, Journal Year: 2017, Volume and Issue: 56(47), P. 15063 - 15067

Published: Oct. 6, 2017

Abstract Chemoselective hydroarylations were accomplished by a novel synergistic Brønsted acid/manganese(I)‐catalyzed C−H activation manifold. Thus, alkynes bearing O‐leaving groups could, for the first time, be employed alkenylations without concurrent β‐O elimination, thereby setting stage versatile late‐stage diversifications. Also described is manganese‐catalyzed in continuous flow, thus enabling efficient within only 20 minutes.

Language: Английский

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