This review describes the recent advances in photocatalyzed reactions to form new carbon–sulfur and carbon–selenium bonds. With a total of 136 references, of which 81 articles are presented, the authors introduce in five sections an updated picture of the state of the art in the light-promoted synthesis of organochalcogen compounds (from 2019 to present). The light-promoted synthesis of sulfides by direct sulfenylation of C–C π-bonds; synthesis of sulfones; the activation of C_sp2–N bond in the formation of C_sp2–S bonds; synthesis of thiol ester, thioether and thioacetal; and the synthesis of organoselenium compounds are discussed, with detailed reaction conditions and selected examples for each protocol.

Ammonium niobium oxalate (ANO) has been proven to be an outstanding cheap, low-toxicity and readily available Lewis acid catalyst for carbonyl activation reactions. Herein, we describe the use of ANO as a catalyst in the Paal–Knorr pyrrole synthesis. The reactions were conducted under mild conditions, not requiring heating or special apparatus, allowing the synthesis of the desired products in up to 99% yield in just 30 min. Additionally, ANO could be reusable up to seven times, without remarkable loss of efficiency. The batch protocol was successfully translated to a continuous-flow environment, with 96% conversion of the starting dione and aniline to the desired pyrrole in 2 min of residence time (a STY of 2.5 g h⁻¹). The main protocol's features meet important green chemistry bases, making it a sustainable method to prepare N-substituted pyrrole derivatives.

Carbon–carbon and carbon-heteroatom bond forming reactions are strategically employed for the generation of a variety of heterocyclic systems. This class of compounds represents the most general structural unit, present in many natural compounds. They are recognized for their valuable biologically properties and wide range of applications in medicinal, pharmaceutical, and other related fields of chemistry. This is an updated review on the use of dicarbonyl compounds under environmentally friendly conditions to access a series of heterocyclic structures, e.g., quinoxaline, quinazolinones, benzochalcogenazoles, indoles, among others. Synthetic protocols involving copper-catalyzed, multicomponent and cascade reactions, decarboxylative cyclization, recycling of CO₂, and electrochemical approaches are presented and discussed.

We developed a promising synthetic methodology for the regioselective photocatalyzed 3-selenocyanation of indoles, employing potassium selenocyanate (KSeCN) and a blue LED light. The 3-selanylindoles have been emerging as a potentially bioactive class of compounds and already have demonstrated anti-inflammatory, antinociceptive and anticancer properties. There are in the literature several methodologies for their preparation; for example, applying intermolecular cyclization with Se-based electrophilic species. Therefore, it is of interest to seek innovative and effective methodologies to selectively access this class of molecules. Furthermore, the photocatalytically formed NCSe· radical can react directly with the N-heterocycle unsaturated substrates, affording the desired compound more effectively than other electrophilic selenium species. In addition, the 3-selenocyanato-1H-indole derivatives can be employed as precursor to obtaining diselenides, through a reduction–oxidation reaction sequence. The new method employs indole as unsaturated N-heterocycle substrate, and 1.3 equiv. of potassium selenocyanate as a selenium source, in the presence of 5.0 mol% of eosin Y, an organic photocatalyst, and 1.0 mL of acetonitrile. The system was stirred and irradiated with a blue LED light for 5 h, and the crude was purified using column chromatography. Thus, as a result, we developed an efficient and smoothly methodology to prepare 3-selenocyanato-1H-indole derivatives, in good yields.

Correction for ‘Ammonium niobium oxalate (ANO) as an efficient catalyst in the Paal–Knorr synthesis of N-substituted pyrroles’ by Luiz H. Dapper et al., RSC Sustain., 2024, https://doi.org/10.1039/d3su00395g.