A general arene C–H functionalization strategy via electron donor-acceptor complex photoactivation

The photoactivation of electron donor-acceptor (EDA) complexes has emerged as a sustainable, selective and versa-tile strategy for the generation of radical species. However, when it comes to aryl radical formation, this strategy remains hamstrung by the electronic properties of the aromatic radical precursors and electron-deficient aryl halide acceptors are required. This has prevented the implementation of a general synthetic platform for aryl radical for-mation. Our study introduces triarylsulfonium salts as acceptors in photoactive EDA-complexes, used in combina-tion with catalytic amounts of newly-designed amine donors. The sulfonium salt label renders inconsequential the electronic features of the aryl radical precursor and, more importantly, it is installed regioselectively in native aro-matic compounds by C–H sulfenylation. Using this general, site-selective aromatic C–H functionalization approach, we have developed metal-free protocols for the alkylation and cyanation of arenes, and showcased their application in both the synthesis and the late-stage modification of pharmaceuticals and agrochemicals.

Aryl radical-mediated N-heterocyclic carbene catalysis

There have been significant advancements in radical reactions using organocatalysts in modern organic synthesis. Recently, NHC-catalyzed radical reactions initiated by single electron transfer processes have been actively studied. However, the reported examples have been limited to catalysis mediated by alkyl radicals. In this article, the NHC organocatalysis mediated by aryl radicals has been achieved. The enolate form of the Breslow intermediate derived from an aldehyde and thiazolium-type NHC in the presence of a base undergoes single electron transfer to an aryl iodide, providing an aryl radical. The catalytically generated aryl radical could be exploited as an arylating reagent for radical relay-type arylacylation of styrenes and as a hydrogen atom abstraction reagent for α-amino C(sp3)–H acylation of secondary amides.

Non-Innocent Radical Ion Intermediates in Photoredox Catalysis: Parallel Reduction Modes Enable Coupling of Diverse Aryl Chlorides

We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated <i>in situ</i>. The combination of isophthalonitrile and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.

Non-Innocent Radical Ion Intermediates in Photoredox Catalysis: Parallel Reduction Modes Enable Coupling of Diverse Aryl Chlorides

We describe a photocatalytic system that elicits potent photoreductant activity from conventional photocatalysts by leveraging radical anion intermediates generated <i>in situ</i>. The combination of isophthalonitrile and sodium formate promotes diverse aryl radical coupling reactions from abundant but difficult to reduce aryl chloride substrates. Mechanistic studies reveal two parallel pathways for substrate reduction both enabled by a key terminal reductant byproduct, carbon dioxide radical anion.

New insight into the electrochemical reduction of different aryldiazonium salts in aqueous solutions

Electrochemical reduction of different aryldiazonium salts in aqueous solution was studied. It is shown that the aryldiazonium salts are converted to the corresponding aryl radical and aryl anion.

Aryl Radical Initiators Accumulated within Layered Silicates Realize Polystyrene with Directly- and Regioselectively-bonded Aryl-terminal Groups

Arbitrary design of a terminal group of polymers exploits the still-veiled functions of polymers with potential for applications in fields such as drug delivery systems, photonics, and energy conversions. Here...