Organic Electrochemistry: Molecular Syntheses with Potential

ACS Central Science, Journal Year: 2021, Volume and Issue: 7(3), P. 415 - 431

Published: March 9, 2021

Efficient and selective molecular syntheses are paramount to

Language: Английский

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Metalla-electrocatalyzed C–H Activation by Earth-Abundant 3d Metals and Beyond

Accounts of Chemical Research, Journal Year: 2019, Volume and Issue: 53(1), P. 84 - 104

Published: Dec. 19, 2019

To improve the efficacy of molecular syntheses, researchers wish to capitalize upon selective modification otherwise inert C-H bonds. The past two decades have witnessed considerable advances in coordination chemistry that set stage for transformative tools functionalizations. Particularly, oxidative C-H/C-H and C-H/Het-H transformations gained major attention because they avoid all elements substrate prefunctionalization. Despite advances, activations been dominated by precious transition metal catalysts based on palladium, ruthenium, iridium, rhodium, thus compromising sustainable nature overall activation approach. same holds true predominant use stoichiometric chemical oxidants regeneration active catalyst, prominently featuring hypervalent iodine(III), copper(II), silver(I) oxidants. Thereby, quantities undesired byproducts are generated, which preventive applications scale. In contrast, elegant merger homogeneous metal-catalyzed with electrosynthesis bears unique power achieve outstanding levels oxidant resource economy. Thus, contrast classical electrosyntheses control, metalla-electrocatalysis huge largely untapped potential unmet site selectivities means catalyst control. While indirect electrolysis using palladium complexes has realized, less toxic expensive base feature distinct beneficial assets toward this Account, I summarize emergence electrocatalyzed earth-abundant 3d metals beyond, a topical focus contributions from our laboratories through November 2019. cobalt electrocatalysis was identified as particularly powerful platform wealth transformations, including oxygenations nitrogenations well alkynes, alkenes, allenes, isocyanides, carbon monoxide, among others. As complementary tools, nickel, copper, very recently iron devised metalla-electrocatalyzed activations. Key success were detailed mechanistic insights, oxidation-induced reductive elimination scenarios. Likewise, development methods make weak O-coordination benefited crucial insights into catalyst's modes action experiment, operando spectroscopy, computation. Overall, thereby syntheses These electrooxidative frequently characterized improved chemoselectivities. Hence, ability dial redox at minimum level required desired transformation renders an ideal functionalization structurally complex molecules sensitive functional groups. This strategy was, inter alia, successfully applied scale-up continuous flow step-economical assembly polycyclic aromatic hydrocarbons.

Language: Английский

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Recent advances in organic electrosynthesis employing transition metal complexes as electrocatalysts

Science Bulletin, Journal Year: 2021, Volume and Issue: 66(23), P. 2412 - 2429

Published: July 13, 2021

Language: Английский

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Electroorganic Synthesis under Flow Conditions

Accounts of Chemical Research, Journal Year: 2019, Volume and Issue: 52(12), P. 3287 - 3296

Published: Nov. 6, 2019

Despite the long history of electroorganic synthesis, it did not participate in mainstream chemical research for a time. This is probably due to lack equipment and standardized protocols. However, nowadays organic electrochemistry witnessing renaissance, wide range interesting electrochemical transformations methodologies have been developed, only academic purposes but also large scale industrial production. Depending on source electricity, methods can be inherently green environmentally benign easily controlled achieve high levels selectivity. In addition, generation consumption reactive or unstable intermediates hazardous reagents achieved safe way. Limitations traditional batch-type such as restricted electrode surface, necessity supporting electrolytes, difficulties scaling up alleviated using flow cells. Microreactors offer surface-to-volume ratios enable precise control over temperature, residence time, rate, pressure. efficient mixing, enhanced mass heat transfer, handling small volumes lead simpler scaling-up protocols minimize safety concerns. Electrolysis under conditions reduces possibility overoxidation reaction mixture flown continuously out reactor contrast electrolysis this Account, we highlight our contributions area synthesis past decade. We designed manufactured different generations The first-generation was effectively used developing simple one-step diaryliodonium salts proof-of-concept reactions trifluoromethylation electron-deficient alkenes via Kolbe trifluoroacetic acid addition selective deprotection isonicotinyloxycarbonyl (iNoc) group from carbonates thiocarbonates. improved second-generation cell enabled development isoindolinones, benzothiazoles, thiazolopyridines, achieving gram-scale some products without changing design reoptimizing parameters. same an continuous hypervalent iodine reagents. generated were isolation various oxidative coupled flow/flow manner could transformed into bench-stable quantitative ligand exchange with appropriate acids. Our further commercialized by Vapourtec Ltd. demonstrated power online analysis accelerating optimizations methodology development. Online spectrometry fast screening charge needed cyclization amides isoindolinones. 2D-HPLC combined Design Experiments approach empowered rapid optimization stereoselective alkoxylations amino derivatives.

Language: Английский

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Electrochemistry-Enabled Ir-Catalyzed Vinylic C–H Functionalization

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(48), P. 18970 - 18976

Published: Nov. 12, 2019

Synergistic use of electrochemistry and organometallic catalysis has emerged as a powerful tool for site-selective C–H functionalization, yet this type transformation thus far mainly been limited to arene functionalization. Herein, we report the development electrochemical vinylic functionalization acrylic acids with alkynes. In reaction an iridium catalyst enables C–H/O–H alkyne annulation, affording α-pyrones good excellent yields in undivided cell. Preliminary mechanistic studies show that anodic oxidation is crucial releasing product regeneration Ir(III) intermediate from diene-Ir(I) complex, which coordinatively saturated, 18-electron complex. Importantly, common chemical oxidants such Ag(I) or Cu(II) did not give significant amounts desired absence electrical current under otherwise identical conditions.

Language: Английский

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Recent advances in cobalt-catalysed C–H functionalizations

Organic & Biomolecular Chemistry, Journal Year: 2019, Volume and Issue: 17(48), P. 10119 - 10141

Published: Jan. 1, 2019

Ready availability, low cost and toxicity of cobalt salts have redirected the attention researchers away from noble metals, such as Pd, Rh, Ir, towards Co in field C-H functionalization. In this context, examples Co-catalysed functionalization exponentially grown over last few decades. This present review focuses on most recent developments C(sp2)-H C(sp3)-H functionalizations. Included is also a comprehensive overview enantioselective transformations.

Language: Английский

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Nickela‐electrocatalyzed C−H Alkoxylation with Secondary Alcohols: Oxidation‐Induced Reductive Elimination at Nickel(III)

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(8), P. 3178 - 3183

Published: Nov. 15, 2019

Abstract Nickela‐electrooxidative C−H alkoxylations with challenging secondary alcohols were accomplished in a fully dehydrogenative fashion, thereby avoiding stoichiometric chemical oxidants, H 2 as the only byproduct. The nickela‐electrocatalyzed oxygenation proved viable various (hetero)arenes, including naturally occurring alcohols, without racemization. Detailed mechanistic investigation, DFT calculations and cyclovoltammetric studies of well‐defined activated nickel(III) intermediate, suggest an oxidation‐induced reductive elimination at nickel(III).

Language: Английский

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Cobalt‐Catalyzed Oxidative C−H Activation: Strategies and Concepts

ChemSusChem, Journal Year: 2020, Volume and Issue: 13(13), P. 3306 - 3356

Published: Feb. 17, 2020

Inexpensive cobalt-catalyzed oxidative C-H functionalization has emerged as a powerful tool for the construction of C-C and C-Het bonds, which offers unique potential transformative applications to modern organic synthesis. In early stage, these transformations typically required stoichiometric toxic transition metals sacrificial oxidants; thus, formation metal-containing waste was inevitable. contrast, naturally abundant molecular O2 more recently been successfully employed green oxidant in cobalt catalysis, thus considerably improving sustainability such transformations. Recently, significant momentum gained by use electricity sustainable environmentally benign redox reagent functionalization, thereby preventing consumption cost-intensive chemicals while at same time addressing considerable safety hazards related oxygen combination with flammable solvents. Considering unparalleled aforementioned approaches synthesis, this Review summarizes recent progress activation until 2020.

Language: Английский

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Electrochemical Access to Aza‐Polycyclic Aromatic Hydrocarbons: Rhoda‐Electrocatalyzed Domino Alkyne Annulations

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(14), P. 5551 - 5556

Published: Dec. 3, 2019

Abstract Nitrogen‐doped polycyclic aromatic hydrocarbons (aza‐PAHs) have found broad applications in material sciences. Herein, a modular electrochemical synthesis of aza‐PAHs was developed via rhodium‐catalyzed cascade C−H activation and alkyne annulation. A multifunctional O‐methylamidoxime enabled the high chemo‐ regioselectivity. The isolation two key rhodacyclic intermediates made it possible to delineate exact order three steps. In addition, metalla‐electrocatalyzed multiple transformation is characterized by unique functional group tolerance, including highly reactive iodo azido groups.

Language: Английский

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Highly Selective Synthesis of 1,3-Enynes, Pyrroles, and Furans by Manganese(I)-Catalyzed C–H Activation

ACS Catalysis, Journal Year: 2019, Volume and Issue: 10(1), P. 197 - 202

Published: Nov. 21, 2019

A highly selective Mn(I)-catalyzed alkenylation of arenes and heteroarenes with 1,3-diynes is described. The reported transformation overcomes regio-, chemo-, stereoselectivity challenges associated the use these coupling partners. Both symmetrical unsymmetrical diynes can be applied in this protocol, affording single isomers not only synthesis 1,3-enynes but also one-step preparation pyrroles furans. This simple strategy features wide functional group tolerance, good reproducibility, preparative scale utility. manganese catalyst plays a crucial role C–H activation enabling high selectivity previously challenging internal alkynes. Furthermore, synthetic value method highlighted by diverse postsynthesis functionalizations final products.

Language: Английский

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