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Radical‐involved arylative cross‐coupling reactions have recently emerged as an attractive strategy to access valuable aryl‐substituted motifs. However, there still exist several challenges such as limited scope of radical precursors/acceptors, and lack of general asymmetric catalytic systems, especially regarding the multicomponent variants. Herein, we reported a general copper‐Box system for asymmetric three‐component arylative radical cross‐coupling of vinylarenes and 1,3‐enynes, with oxime carbonates and aryl boronic acids. The reactions proceed under practical conditions in the absence or presence of visible‐light irradiation, affording chiral 1,1‐diarylalkanes, benzylic alkynes and allenes with good enantioselectivities. Mechanistic studies imply that the copper/Box complexes play a dual role in both radical generation and ensuing asymmetric cross‐coupling. In the cases of 1,3‐enynes, visible‐light irradiation could improve the activity of copper/Box complex toward the initial radical generation, enabling better efficiency match between radical formation and cross‐coupling. [ABSTRACT FROM AUTHOR]

Catalytic and switchable C−H functionalization of N‐heteroarenes under easily tunable conditions is a robust but challenging tool for the construction of biologically relevant compounds. Recently, a general electrochemical strategy has been developed for the direct C−H carboxylation of N‐heteroarenes with CO2, and by simply choosing different types of cell setups, carboxylated products are furnished with excellent and tunable site selectivity. This study also paves the way for regulating the reactivity modes in electrochemical synthesis. [ABSTRACT FROM AUTHOR]

Kharasch–Sosnovsky reaction is one of the most powerful methods for allylic oxidation of alkenes. However, the inherent radical mechanism and use of peroxides as both oxidants and oxygen nucleophiles render dearth of universal catalytic systems for highly enantioselective variants and limited scope. Herein, an alternative to the asymmetric Kharasch–Sosnovsky reaction that utilized a chiral copper catalyst and purple‐LED irradiation to enable the three‐component coupling of 1,3‐dienes, oxime esters, and carboxylic acids is reported. This protocol features mild conditions, remarkable scope and functional group tolerance as evidenced by >80 examples and utility in the late‐stage modification of pharmaceuticals and natural products. Detailed mechanistic studies provide evidences for the radical‐based reaction pathway. [ABSTRACT FROM AUTHOR]

An unprecedented dual photoredox/palladium-catalyzed iminyl-radical-mediated C–C bond cleavage and directed ortho C–H acylation of 2-arylpyridines by using oxime esters is described. Oxime esters can serve as efficient acyl sources through formation of the corresponding acyl radicals by photoredox-catalyzed iminyl-radical-mediated C–C bond cleavage. This redox-neutral protocol features excellent regioselectivity, a broad substrate scope, and good functional-group tolerance with respect to both components, giving a broad range of aryl ketones with generally good yields. [ABSTRACT FROM AUTHOR]

A photoredox-catalyzed iminyl radical-triggered C–C bond cleavage/addition/Kornblum oxidation cascade of cycloketone oxime esters and styrenes in DMSO is described. This three-component, one-pot procedure features mild conditions, a broad substrate scope, and high functional group tolerance, providing an efficient approach to access diversely functionalized ketonitriles. [ABSTRACT FROM AUTHOR]

Abstract: The control of selectivity in the reactions of the highly reactive open‐shell carbon radicals is an attractive but often challenging task. Building on the strategy of photoinduced iminyl radical‐mediated C−C bond cleavage, we have developed photocatalytic neophyl rearrangement and reduction of distal carbon radicals under visible light irradiation of O‐acyl oximes. This mild protocol tolerates a wide range of readily available O‐acyl oximes, enabling facile synthesis of diversely substituted α,β‐unsaturated nitriles and β‐functionalized saturated nitriles in a highly selective manner. [ABSTRACT FROM AUTHOR]

On the basis of the strategy of iminyl radical-mediated C–C bond cleavage, a visible light photocatalytic radical addition/cyclization cascade is described, providing an efficient and regioselective access to cyanoalkylated 1,2,3,4-tetrahydrophenanthrenes. [ABSTRACT FROM AUTHOR]

Abstract: A room‐temperature, visible‐light‐driven N‐centered iminyl radical‐mediated and redox‐neutral C−C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has been accomplished. The strategy tolerates a wide range of O‐acyl oximes and unsaturated systems, such as alkenes, silyl enol ethers, alkynes, and isonitrile, enabling highly selective formation of various chemical bonds. This method thus provides an efficient approach to various diversely substituted cyano‐containing alkenes, ketones, carbocycles, and heterocycles. [ABSTRACT FROM AUTHOR]

The construction of carbon-heteroatom bonds is one of the most active areas of research in organic chemistry because the function of organic molecules is often derived from the presence of heteroatoms. Although considerable advances have recently been achieved in radical-involved catalytic asymmetric C-N bond formation, there has been little progress in the corresponding C-O bond-forming processes. Here, we describe a photoinduced copper-catalyzed cross-coupling of readily available oxime esters and 1,3-dienes to generate diversely substituted allylic esters with high regio- and enantioselectivity (>75 examples; up to 95% ee). The reaction proceeds at room temperature under excitation by purple light-emitting diodes (LEDs) and features the use of a single, earth-abundant copper-based chiral catalyst as both the photoredox catalyst for radical generation and the source of asymmetric induction in C-O coupling. Combined experimental and density functional theory (DFT) computational studies suggest the formation of π-allylcopper complexes from redox-active oxime esters as bifunctional reagents and 1,3-dienes through a radical-polar crossover process.

Catalytic enantioselective chemical reactions involving highly reactive radical species remain largely unexplored. We report herein for the first time a novel enantioselective radical ring-opening cyanation of redox-active oxime esters by dual photoreodox and copper catalysis. This mild protocol shows good functional group tolerance and broad substrate scope, producing a wide range of optically active alkyl dinitriles with high yields and excellent enantioselectivities, which are difficult to access traditionally.

A light-driven, metal-free, and iminyl radical-mediated ring-opening C-C bond cleavage/addition cascade of O -4-methoxybenzyl oxime ethers and alkenes is described for the first time. The reaction shows a broad substrate scope and high functional group compatibility with both components, giving the corresponding valuable oxo nitriles in generally good yields. Key to the success of this protocol is the generation of cyclic iminyl radicals from the O -4-methoxybenzyl oxime ethers via a photocatalytic hydrogen atom transfer (HAT) process. The proposed main pathway is also supported by the preliminary mechanistic studies.

A photoinduced, copper-catalyzed three-component radical cross-coupling of cycloketone oxime esters, alkenes, and terminal alkynes is described for the first time. Key to the success of this process was the integration of photoinduced iminyl radical-mediated C-C bond cleavage with the conceptual simplicity of copper-catalyzed radical cross-coupling. This protocol provides access to cyanoalkyl-containing propargylic compounds in good yields.

A dual visible light photoredox and nickel-catalyzed cross-coupling reaction of 2-arylaziridines and potassium benzyltrifluoroborates is described for the first time. This strategy features high functional group tolerance, exclusive regioselectivity for reaction at the more hindered C-N bond, easily accessible substrates, and mild redox-neutral reaction conditions. A variety of diversely substituted β-substituted amines are obtained in generally good yields.

A room-temperature, visible-light-driven N-centered iminyl radical-mediated and redox-neutral C-C single bond cleavage/radical addition cascade reaction of oxime esters and unsaturated systems has been accomplished. The strategy tolerates a wide range of O-acyl oximes and unsaturated systems, such as alkenes, silyl enol ethers, alkynes, and isonitrile, enabling highly selective formation of various chemical bonds. This method thus provides an efficient approach to various diversely substituted cyano-containing alkenes, ketones, carbocycles, and heterocycles., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)