Hydrogen and Sulfonyl Radical Generation for the Hydrogenation and Arylsulfonylation of Alkenes Driven by Photochemical Activity of Hydrogen Bond Donor‐Acceptor Complexes

Visible-light-driven catalyst-free C-S cross-coupling of thiol derivatives and aryl halides

A mild, scalable, and high-yielding visible-light-promoted C-S cross-coupling between alkyl thiol derivatives and (hetero)aryl halides without the need for metals, ligands, or photocatalysts is reported, offering advantages over traditional C-S bond forming strategies. The formation of an electron donor-acceptor (EDA) complex is supported by experimental and computational mechanistic studies, which undergoes visible-light-induced charge transfer to initiate C-S bond formation in the absence of a photoredox catalyst.

DFT study of electron donor-acceptor (EDA) complexes: mechanism exploration and theoretical prediction

Organic synthesis methods initiated by visible light have received increasing attention from synthetic chemists. Reactions initiated by EDA complexes do not require the use of toxic or expensive photoredox catalysts, unlike traditional photoreaction processes. However, this kind of reaction requires a particular structure for the substrate, so it is important to study the detailed and systematic reaction mechanism for its design. EDA complexes of substituted 1H-indole and substituted benzyl bromide derivatives were studied by density functional theory (DFT). The difference between EDA complexes with substituents of different kinds and locations were compared by theoretical study and a new EDA complex was predicted.

Visible-Light-Mediated Three-Component Cascade Sulfonylative Annulation

Visible-light-promoted cascade radical cyclization for the synthesis of sulfonylated benzimidazo/indolo[2,1-a]iso-quinolin-6(5H)-ones has been reported. The reaction provides transition-metal-free and expeditious access to sulfonylated polyaromatics. The use of sodium metabisulfite as a SO₂ surrogate and the rapid generation of molecular complexity using a three-component photochemical protocol are the salient features of this reaction manifold.

Organic Sulfinic Acids and Salts in Visible Light-Induced Reactions

Sulfinic acids and their salts are a useful source of sulfur-containing structures. Photocatalysis of these compounds with visible light enables to achieve various transformations under mild conditions. This review summarizes visible-light-induced reactions of sulfinic acids and their salts. It is organized by reaction type and brief discussions on plausible reaction mechanisms for typical transformations are presented.

1 Introduction

2 Sulfonylation Reactions

2.1 Sulfonylation of Alkenes

2.2 Sulfonylation of Alkynes

2.3 Sulfonylation of Arenes

2.4 sp3 C–H Functionalization

3 Desulfonylation Reactions

4 Sulfenylation Reactions

4.1 Sulfenylation of Heteroarenes

4.2 Sulfenylation of Carbonyl Chlorides

5 Conclusions

Visible-Light-Induced Decarboxylative Cyclization/Hydrogenation Cascade Reaction to Access Phenanthridin-6-yl(aryl)methanol by an Electron Donor-Acceptor Complex

A novel and efficient visible-light-induced decarboxylative cyclization/hydrogenation cascade reaction of α-oxocarboxylic acids and 2-isocyanobiaryls has been developed. Without the need of any external photosensitizer, oxidant, and reductant, this method offers a mild and green approach for the synthesis of diverse alcohols in moderate to good yields. A mechanism indicated that an electron donor-acceptor complex-driven decarboxylation, radical addition/cyclization, and in situ photochemical reduction of ketones to alcohols could be involved in the reaction.

Visible-Light-Induced Deaminative Thioesterification of Amino Acid Derived Katritzky Salts via Electron Donor-Acceptor Complex Formation

A visible-light-mediated deaminative thioesterification of amino acid derived Katritzky salts with thiobenzoic acid has been developed, which provides a novel synthetic method for the synthesis of α-mercapto acid derivatives under mild conditions. This photoredox catalyst-free generation of alkyl radicals via C-N bond cleavage is enabled by the formation of an electron-donor-acceptor (EDA) complex between the Katritzky salt and thiobenzoic acid anion, which represents a new entry for EDA complex chemistry.