Themed collection FOCUS: Radical-involved chemical transformations

Photoinduced strategies towards radical reactions of [1.1.1]propellane and bicyclo [1.1.0]butanes by photoredox or metallaphotoredox catalysis have recently been disclosed, enabling controllable construction of 1,3-difunctionalized bicyclo[1.1.1]pentanes and cyclobutanes.

Alcohols and carboxylic acids have been established as versatile building blocks in the assembly of various carbon frameworks.

Dual N-heterocyclic carbene/photocatalysis displays unique features compared with the traditional methods and indicates high potential for new radical processes.

This review is devoted to highlighting main achievements in the development of cascade radical cyclization of radical acceptors for the synthesis of carbo- and heterocycles.

The application of the cyano group as a radical acceptor in the cascade reactions for the construction of various important heterocycles and carbocycles was summarized.

Significant progress in the chemistry of nitro radicals has been witnessed in the past decades, providing efficient and rapid access to nitro-containing compounds. This review describes recent advances in nitro-involved radical reactions, and summarizes various transformations.

Chiral hydrogen-bonding catalysis is a classic strategy in asymmetric organocatalysis. Recently, it has been used to cooperate with photoredox catalysis, becoming a powerful tool to access optical pure compounds via radical-based transformations.

In this review, we have focused on the recent advances in photocatalytic C–S/P–S bond formation via the generation of thioyl/sulfonyl radicals and further functionalization.

This review is focused on the recent advances in the chemistry of sulfur dioxide fixation through a radical process. Diverse sulfonyl compounds can be obtained efficiently under mild conditions.

A novel photoredox-catalyzed C(sp³)–C(sp³) cross-coupling between N-arylamines and cycloketone oxime esters under mild conditions has been accomplished.

The radical aminophosphinoylation of maleimides with anilines and diarylphosphine oxides.

Transformer, a sequence-to-sequence deep learning model, is capable of predicting the reaction intermediates of radical cascade cyclization. This study provides a novel approach to help chemists discover the mechanisms of organic reactions.

The first approach of photoredox catalyzed radical–radical cross-coupling difluoromethylation of C(sp³)−H bond was reported, featuring transition metal-free, good functional group tolerance, broad substrate scope and mild reaction conditions.

We report here a radical hydrotrifluoromethylation of ynamides to provide an alternative route toward β-CF₃ enamides.

A visible-light-promoted radical amidation/cyclization of arylacrylamides was realized by using N-aminopyridinium salts as the source of amidyl radicals. A variety of amide-tethered-oxindoles were prepared in this way in moderate to good yields.

Radical chain cyclization of aryl iodides provides an efficient synthesis of planar Blatter radicals, and, for the first time, access to functionalized sulphur-containing analogues.

Alkyloxalyl chlorides, generated from alcohols and oxalyl chlorides, are used as alkoxycarbonyl radicals in the reaction of N-acryloyl benzamides under photocatalysis at room temperature.

Instantaneous and spontaneous room temperature C–ON bond mesolysis of alkoxyamines triggered by chemical oxidation.

A highly regioselective Ni-catalyzed electrochemical (undivided cell) reductive relay cross-coupling between alkyl carboxylic acids and alkyl bromides has been developed.

Described herein is the radical-mediated heteroarylation of unactivated remote C(sp³)–H bonds via intramolecular heteroaryl migration.

We report a radical cross-coupling of cycloketone oxime esters with aldehydes by N-heterocyclic carbene (NHC) organocatalysis. This protocol features easy operation, with no need for external redox reagent, and a broad functional group compatibility.

Radical cations and dications of three isomeric bis[1]benzothieno[1,4]thiazines are (electro)chemically generated, spectroscopically characterized and assigned by (TD)DFT calculations.

A radical Smiles rearrangement strategy for allowing an unprecedented [3 + 2]/[3 + 2] carboannulation of dienynes with arylsulfonyl chlorides using cheap copper catalysis is described.

A novel method for the construction of 1,5-methanobenzo[f][1,3]oxazocin-6-ones and 6,10-methanopyrido[3,2-f][1,3]oxazocin-5-ones from o-vinyl aromatic aldehydes and N-acylarylimines was developed via NHC-catalyzed and radical-initiated reactions.

A Brønsted acid-catalyzed radical addition reaction between chromenols and toluene derivatives was accomplished under light irradiation, affording benzylated chromene derivatives through benzylic C(sp³)–H functionalization of toluene derivatives.

Symmetric trimeric and dimeric indole alkaloids were isolated for the first time from Bousigonia angustifolia, and they could be constructed through Friedel–Crafts and free radical reactions, respectively.

A visible-light-promoted free radical cross coupling of hypervalent bis-catecholato silicon compounds with selenosulfonates or thiosulfonates is developed.

Metallaphotoredox catalysis for furan synthesis: The cyclisation of yne-enones proceeds smoothly via consecutive reductive radical-polar crossover and cycloisomerization processes enabled by cooperative photoredox-neutral and copper catalysis.

Triarylamines are demonstrated as novel, tunable electroactivated photocatalysts that use dispersion precomplexation to harness the full potential of the visible photon (>4.0 V vs. SCE) in anti-Kasha photo(electro)chemical super-oxidations of arenes.

A copper-catalyzed radical oxycyanation of unactivated alkenes and styrenes to produce beta-cyanohydrin derivatives with the cyano group attached on the more substituted carbon center was reported.

A glimpse into uncharted territory: the synthesis and study of dicationic dioxolium salts allow for assessing the fate of the corresponding elusive dioxolyl radicals.

A metal-free photoredox catalyzed decarboxylative radical coupling of free-carboxylic acids and glyoxylic oximes was developed to synthesize α,β-diamino acids.

Reaction of unactivated alkenes affords various fluoroalkyl-containing alkyl sulfonyl fluorides with good functional group tolerance under mild conditions.

Anion–π-radical interaction plays a key role in photophysical and magnetic properties.

Combination of 1,10-phenanthroline and potassium carbonate enables a radical cleavage of a hydrazonyl N–S bond, allowing a coupling reaction of N-tosylhydrazone and phosphinyl allene via cascade C–O cleavage, sulfonyl rearrangement and atropisomeric cyclopropanation.

A mild and simple protocol is developed for the synthesis of terminal alkenes via site-specific C–C bond formation upon visible-light irradiation.

A photoredox-catalyzed method for the indirect generation of acyl radicals from stable thioesters is described.

An electrochemical synthesis of functionalized 7-membered carbocycles through a 5-exo-trig/7-endo-trig radical cyclization cascade has been developed.

Concomitant anti-Markovnikov hydrofunctionalization of alkenes and oxidation of remote alcohols are achieved through intramolecular 1,5(6)-hydrogen atom transfer.

The first example of a metal- and reductant-free deoxygenative sulfonylation of quinoline N-oxides with sodium sulfinates via a dual radical coupling process is reported.

Photocatalytic carboxylic radical aromatic substitution enables the synthesis of diversely substituted coumarins by inert C–X bond cleavage under mild conditions.

Oxidative C–O coupling of oximes, N-hydroxyphthalimide, and N-hydroxybenzotriazole with pyrazolones via formation of N-oxyl radicals is described.