Nitrogen-Centered Radicals in Functionalization of sp² Systems: Generation, Reactivity, and Applications in Synthesis

Chemical Reviews, Journal Year: 2022, Volume and Issue: 122(9), P. 8181 - 8260

Published: March 14, 2022

The chemistry of nitrogen-centered radicals (NCRs) has plentiful applications in organic synthesis, and they continue to expand as our understanding these reactive species increases. utility intermediates is demonstrated the recent advances C–H amination (di)amination alkenes. Synthesis previously challenging structures can be achieved by efficient functionalization sp2 moieties without prefunctionalization, allowing for faster more streamlined synthesis. This Review addresses generation, reactivity, application NCRs, including, but not limited to, iminyl, aminyl, amidyl, aminium species. Contributions from early discovery up most examples have been highlighted, covering radical initiation, thermolysis, photolysis, and, recently, photoredox catalysis. Radical-mediated intermolecular (hetero)arenes occur with a variety complex amine precursors, generating aniline derivatives, an important class drug development. Functionalization olefins achievable high anti-Markovnikov regioselectivity allows access difunctionalized when intermediate carbon are trapped. Additionally, reactivity NCRs harnessed rapid construction N-heterocycles such pyrrolidines, phenanthridines, quinoxalines, quinazolinones.

Language: Английский

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Supramolecular Coordination Cages for Artificial Photosynthesis and Synthetic Photocatalysis

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(9), P. 5225 - 5261

Published: Jan. 20, 2023

Because sunlight is the most abundant energy source on earth, it has huge potential for practical applications ranging from sustainable supply to light driven chemistry. From a chemical perspective, excited states generated by make thermodynamically uphill reactions possible, which forms basis storage into fuels. In addition, with light, open-shell species can be open up new reaction pathways in organic synthesis. Crucial are photosensitizers, absorb and transfer substrates various mechanisms, processes that highly depend distance between molecules involved. Supramolecular coordination cages well studied synthetically accessible vessels single cavities guest binding, ensuring close proximity of different components. Due high modularity their size, shape, nature metal centers ligands, ideal platforms exploit preorganization photocatalysis. Herein we focus application supramolecular photocatalysis artificial photosynthesis photo(redox) catalysis. Finally, brief overview immobilization strategies provides tools implementing devices. This review inspiration future design photocatalytic host-guest systems producing solar fuels complex molecules.

Language: Английский

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Electrochemical Late-Stage Functionalization

Chemical Reviews, Journal Year: 2023, Volume and Issue: 123(19), P. 11269 - 11335

Published: Sept. 26, 2023

Late-stage functionalization (LSF) constitutes a powerful strategy for the assembly or diversification of novel molecular entities with improved physicochemical biological activities. LSF can thus greatly accelerate development medicinally relevant compounds, crop protecting agents, and functional materials. Electrochemical synthesis has emerged as an environmentally friendly platform transformation organic compounds. Over past decade, electrochemical late-stage (eLSF) gained major momentum, which is summarized herein up to February 2023.

Language: Английский

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Aroyl Fluorides as Bifunctional Reagents for Dearomatizing Fluoroaroylation of Benzofurans

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(16), P. 7072 - 7079

Published: March 22, 2022

The 2,3-dihydrobenzofuran scaffold is widely found in natural products and biologically active compounds. Herein, dearomatizing 2,3-fluoroaroylation of benzofurans with aroyl fluorides as bifunctional reagents to access 2,3-difunctionalized dihydrobenzofurans reported. reaction that occurs by cooperative NHC/photoredox catalysis provides 3-aroyl-2-fluoro-2,3-dihydrobenzofurans moderate good yield high diastereoselectivity. Cascades proceed via radical/radical cross-coupling a benzofuran radical cation generated the photoredox cycle neutral ketyl formed through NHC cycle. redox-neutral transformation exhibits broad substrate scope functional group compatibility. With anhydrides reagents, aroyloxyacylation achieved strategy can also be applied

Language: Английский

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Photoinduced Oxygen Transfer Using Nitroarenes for the Anaerobic Cleavage of Alkenes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(34), P. 15437 - 15442

Published: Aug. 5, 2022

Herein we report the anaerobic cleavage of alkenes into carbonyl compounds using nitroarenes as oxygen transfer reagents under visible light. This approach serves a safe and practical alternative to mainstream oxidative protocols, such ozonolysis Lemieux–Johnson reaction. A wide range possessing oxidatively sensitive functionalities underwent generate derivatives with high efficiency regioselectivity. Mechanistic studies support that transformation occurs via direct photoexcitation nitroarene followed by nonstereospecific radical cycloaddition event alkenes. leads 1,3,2- 1,4,2-dioxazolidine intermediates fragment give products. combination clock experiments in situ photoNMR spectroscopy revealed identities key species putative aryl dioxazolidine intermediates, respectively.

Language: Английский

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Recent advances in the electrochemical generation of 1,3-dicarbonyl radicals from C–H bonds

Organic Chemistry Frontiers, Journal Year: 2023, Volume and Issue: 10(11), P. 2830 - 2848

Published: Jan. 1, 2023

Recent advances in the electrochemical generation of 1,3-dicarbonyl radicals from C–H bonds and their mechanistic insights synthetic applications have been summarized.

Language: Английский

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CdS Quantum Dots as Potent Photoreductants for Organic Chemistry Enabled by Auger Processes

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(27), P. 12229 - 12246

Published: June 30, 2022

Strong reducing agents (<−2.0 V vs saturated calomel electrode (SCE)) enable a wide array of useful organic chemistry, but suffer from variety limitations. Stoichiometric metallic reductants such as alkali metals and SmI2 are commonly employed for these reactions; however, considerations including expense, ease use, safety, waste generation limit the practicality methods. Recent approaches utilizing energy multiple photons or electron-primed photoredox catalysis have accessed reduction potentials equivalent to Li0 shown how this enables selective transformations aryl chlorides via radicals. However, in some cases, low stability catalytic intermediates can turnover numbers. Herein, we report ability CdS nanocrystal quantum dots (QDs) function strong photoreductants present evidence that highly electron is generated two consecutive photoexcitations QDs with intermediate reductive quenching. Mechanistic experiments suggest Auger recombination, photophysical phenomenon known occur photoexcited anionic QDs, generates transient thermally excited electrons observed reductions. Using blue light-emitting diodes (LEDs) sacrificial amine reductants, phosphate esters up −3.4 SCE photoreductively cleaved afford hydrodefunctionalized functionalized products. In contrast small-molecule catalysts, stable under conditions numbers 47 500 been achieved. These also effect other challenging reductions, tosylate protecting group removal amines, debenzylation benzyl-protected alcohols, ring opening cyclopropane carboxylic acid derivatives.

Language: Английский

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Photochemistry Journey to Multielectron and Multiproton Chemical Transformation

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(36), P. 16219 - 16231

Published: Sept. 2, 2022

The odyssey of photochemistry is accompanied by the journey to manipulate "electrons" and "protons" in time, space, energy. Over past decades, single-electron (1e-) photochemical transformations have brought marvelous achievements. However, as each photon absorption typically generates only one exciton pair, it exponentially challenging accomplish multielectron proton transformations. multistep differences thermodynamics kinetics urgently require us optimize light harvesting, expedite consecutive electron transfer, interaction catalysts with substrates, coordinate transfer furnish selective bond formations. Tandem catalysis enables orchestrating different events catalytic from subpicoseconds seconds, which facilitates redox chemistries brings consecutive, value-added reactivities. Joint efforts molecular material design, mechanistic understanding, theoretical modeling will bring synthetic opportunities for fuels, fertilizers, chemicals enhanced versatility, efficiency, selectivity, scalability, thus taking better advantage photons (i.e., sunlight) our sustainable society.

Language: Английский

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Resurgence and advancement of photochemical hydrogen atom transfer processes in selective alkane functionalizations

Chemical Science, Journal Year: 2023, Volume and Issue: 14(25), P. 6841 - 6859

Published: Jan. 1, 2023

The selective functionalization of alkanes has long been recognized as a prominent challenge and an arduous task in organic synthesis. Hydrogen atom transfer (HAT) processes enable the direct generation reactive alkyl radicals from feedstock have successfully employed industrial applications such methane chlorination process,

Language: Английский

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A tutorial on asymmetric electrocatalysis

Chemical Society Reviews, Journal Year: 2023, Volume and Issue: 52(23), P. 8106 - 8125

Published: Jan. 1, 2023

This tutorial review delves into the unique advantages of electrochemistry in context asymmetric catalysis, first providing a brief introduction to electrosynthesis, then exploring representative case studies with mechanistic focus.

Language: Английский

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