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A functionalization of benzylic C(sp3)–H bonds was established through a mild metal-free intramolecular lactonization protocol in the presence of DDQ/ tert -butyl nitrite as photocatalysts, allowing practical and low-cost access to a series of phthalide products in moderate to excellent yields. Compared with many existing methodologies, this visible-light-driven process exhibits an excellent substrate scope and fascinating features, including the formation of water as the sole byproduct, an abundant and green energy source, commercially available catalysts, and room-temperature reaction. Finally, detailed mechanistic investigations clearly revealed the role of the photocatalysts and molecular oxygen. [ABSTRACT FROM AUTHOR]

A green protocol for construction of C−Se bonds from ketene dithioacetals and diselenides through direct electrochemical oxidative cross-coupling has been developed. This reaction was carried out in an undivided cell system with NaBF4 as the electrolyte and CH3CN as the solvent through galvanostatic electrolysis. A series of substituted ketene dithioacetals and diselenides were tolerant and the desired tetrasubstituted alkenyl selenides were obtained in moderate to excellent yields. In addition, construction of C−S bond from ketene dithioacetals and disulfides through electrochemical method in the presence of KI was also successfully realized. It exhibited high efficiency and broad functional group tolerance. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: α‐Fluoroalkyl (Rf) alcohols are privileged motifs in drugs and pharmaceutically active compounds. As such, it is highly desirable to develop efficient methods for assembling these scaffolds. Herein, a visible‐light‐induced cascade radical cyclization of alkenyl fluoroalkyl ketones is developed, producing a variety of decorate α‐Rf cycloalkanols in promising yields with up to >20 : 1 dr selectivity. A radical chain mechanism involving an intramolecular radical addition to the α‐Rf carbonyl group and a subsequent intermolecular hydrogen atom transfer (HAT) has been proposed. Density functional theory (DFT) calculations indicate that a fluorine effect contributes to the radical addition to carbonyls by lowering the π* (C=O) orbital energy of CORf and energy barrier of the HAT between alkoxy radicals and THF, which may be valuable for controllable transformations of fluorinated molecules. [ABSTRACT FROM AUTHOR]

A green and practical electrooxidation protocol for C3 acyloxylation of 2H-indazoles with carboxylic acids in the presence of potassium carbonate has been developed by intermolecular cross-dehydrogenative C(sp2)–O coupling. It is sustainable without the use of transition-metal catalysts, stoichiometric oxidants, and even extra supporting electrolytes. Potassium carbonate plays a key role in the reaction, and reacts with carboxylic acids to form carboxylates. Mechanistic studies by cyclic voltammetry and control experiments reveal that the reaction proceeds via an ECE mechanism. In addition, various carboxylic acids and 2H-indazoles are suitable in this system and provide a series of novel desired products at room temperature in an undivided cell. [ABSTRACT FROM AUTHOR]