Photoinduced reductive coupling of carbonyl compounds and α,β-unsaturated esters via ketyl radical intermediates for the synthesis of γ-lactones is described.

Light-driven [2 + 2] cycloaddition of olefins is a kind of atom-economic and green transformation for building cyclobutane scaffolds, which are widely found in bioactive compounds and natural products. Although great progress has been made in the (dia)stereoselective synthesis of anti-cyclobutanes by photocycloadditions, the selective synthesis of syn-cyclobutanes is still full of challenges. Herein, we report a visible light-triggered and catalyst- and template-free [2 + 2] cycloaddition strategy of chalcones as a solid-state reaction in water to afford syn-cyclobutanes in high yields with excellent diastereoselectivity.

A visible-light-initiated radical cascade reaction toward the synthesis of structurally diverse fused Indolo-pyridones is described. The reaction involves the addition of aroyl or sulfonyl radicals to N-alkyl-acryloyl-1H-indole-3-carboxamides, cyclization, and oxidative aromatization. This telescoped method circumvents lengthy prefunctionalization steps of radical precursors, which is further underpinned by the superior compatibility with a series of C-centered radicals, allowing the rapid and facile construction of numerous valuable architectures.

A copper-catalyzed, facile and efficient approach for the synthesis of 3-arylquinolin-2-ones starting from (E)-3-(2-bromophenyl)-2-arylacrylamides has been developed. Readily avail-able starting materials, noble metal-and ligand-free conditions, as well as good tolerability for phenolic groups make this protocol attractive and practicable.