A photoredox activation mode of formate salts for carboxylation was developed. Using a formate salt as the reductant, carbonyl source, and hydrogen atom transfer reagent, a wide range of alkenes can be converted into acid products via a carboxyl group transfer strategy in an additive-free fashion. Mechanistic studies revealed that radical anion species (CO2 •– and carbon radical anions derived from the reduction of alkenes) are key intermediates of the transformation. This method has the advantages of high catalytic efficiency and a simple catalytic system, which may allow this approach to become a promising strategy for industrial applications.

In recent decades, difunctionalization of alkenes has received considerable attention as an efficient and straightforward way to increase molecular complexity. However, examples of the difunctionalization of alkenes initiated by the intermolecular addition of alkoxycarbonyl radicals providing substituted alkanoates are still rare. Herein, we present the visible light-driven metal-free divergent difunctionalization of alkenes triggered by the intermolecular addition of alkoxycarbonyl radicals under ambient conditions. Employing alkyl formates as precursors of alkoxycarbonyl radicals and 4CzIPN as the photocatalyst, a variety of substituted alkanoates, including β-alkoxy, β-hydroxy, β-dimethoxymethoxy, and β-formyloxy alkanoates, could be facilely accessed with high functional group tolerance and high efficiency. Moreover, the mechanism study revealed that β-hydroxy alkanoates were generated by a selective decomposition of orthoformates promoted by the N-alkoxyazinium salt.

A highly efficient, Iron nitrate/TEMPO-catalyzed approach for the synthesis of quinazolinones has been achieved via a onepot, tandem aerobic oxidative cyclization of primary alcohols with 2-aminobenzamides. This practical reaction tolerates a broad scope of substrates and could afford a variety of desirable products in good to excellent yields with air as the terminal green oxidant. Thus, the present synthetic protocol provides an efficient and concise strategy for the synthesis of quinazolinones.Scheme 1. Examples of synthetic and natural quinazolinones.

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