Visible-Light-Mediated Divergent and Regioselective Vicinal Difunctionalization of Styrenes with Arylazo Sulfones

Water Effect on the Photochemistry of Arylazo Sulfonates

The effect of water on visible-light-driven generation of aryl radicals or aryl cations from colored shelf-stable arylazo sulfonates has been investigated. Photoinduced ionic and radical decomposition of these salts compete, depending on the media used. In organic solvents, light-induced homolysis of the N-S bond occurs, and the resulting aryl radical may be used to some extent for arylation reactions. On the contrary, in neat water, radical chemistry is prevented by an efficient photoheterolysis, and a reactive aryl cation is otherwise generated.

Aminosulfonylation of Rhodium Carbene via Ylide Formation and 1,4-Sulfonyl Rearrangement

We report here the use of pyridin-2-yl benzenesulfonates as sulfonylation reagents in a difunctionalization reaction based on oxy-pyridinium ylide chemistry, providing an effective protocol for the installation of both a sulfonyl group and a pyridone moiety into one molecule. Density functional theory (DFT) calculations disclose that the reaction process might proceed through sequential metal-bound ylide formation, keto-enol tautomerism, and the migratory rearrangement of the sulfonyl group.

Generation and Application of Aryl Radicals Under Photoinduced Conditions

Photoinduced aryl radical generation is a powerful strategy in organic synthesis that facilitates the formation of diverse carbon-carbon and carbon-heteroatom bonds. The synthetic applications of photoinduced aryl radical formation in the synthesis of complex organic compounds, including natural products, physiologically significant molecules, and functional materials, have received immense attention. An overview of current developments in photoinduced aryl radical production methods and their uses in organic synthesis is given in this article. A generalized idea of how to choose the reagents and approach for the generation of aryl radicals is described, along with photoinduced techniques and associated mechanistic insights. Overall, this article offers a critical assessment of the mechanistic results as well as the selection of reaction parameters for specific reagents in the context of radical cascades, cross-coupling reactions, aryl radical functionalization, and selective C-H functionalization of aryl substrates.

Visible photons as ideal reagents for the activation of coloured organic compounds

In recent decades, the traceless nature of visible photons has been exploited for the development of efficient synthetic strategies for the photoconversion of colourless compounds, namely, photocatalysis, chromophore activation, and the formation of an electron donor/acceptor (EDA) complex. However, the use of photoreactive coloured organic compounds is the optimal strategy to boost visible photons as ideal reagents in synthetic protocols. In view of such premises, the present review aims to provide its readership with a collection of recent photochemical strategies facilitated via direct light absorption by coloured molecules. The protocols have been classified and presented according to the nature of the intermediate/excited state achieved during the transformation.