Herein, we report a greener protocol for the synthesis of 3-Se/S-indoles and imidazo[1,2-a]pyridines through direct C(sp )-H bond chalcogenation of heteroarenes with half molar equivalents of different dichalcogenides, using KIO as a non-toxic, easy-to-handle catalyst and a stoichiometric amount of glycerol. The reaction features are high yields, based on atom economy, easy performance on gram-scale, metal- and solvent-free conditions as well as applicability to different types of N-heteroarenes.

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Herein, we describe a simple and efficient route to access aniline-derived diselenides and evaluate their antioxidant/GPx-mimetic properties. The diselenides were obtained in good yields via ipso-substitution/reduction from the readily available 2-nitroaromatic halides (Cl, Br, I). These diselenides present GPx-mimetic properties, showing better antioxidant activity than the standard GPx-mimetic compounds, ebselen and diphenyl diselenide. DFT analysis demonstrated that the electronic properties of the substituents determine the charge delocalization and the partial charge on selenium, which correlate with the catalytic performances. The amino group concurs in the stabilization of the selenolate intermediate through a hydrogen bond with the selenium.

Herein, we describe an efficient and selective Cucatalyzed CÀ H bond chalcogenation of the indolizine core, in the presence of DMSO and applying ultrasound irradiation as an alternative energy source. Under the optimal conditions, 3-sulfanylindolizines (16 examples) were prepared in moderate to good yields starting from diorganyl disulfides and 2-arylindolizines. When diphenyl diselenide was used, 1,3-bis (selanyl) indolizines (4 examples) were exclusively obtained in very good yields. The use of ultrasound irradiation makes the reaction faster and more selective when compared to conventional heating.

Herein, we report the microwave-assisted synthesis of 1,3-diynes from terminal acetylenes, catalyzed by CuI and tetramethylethylenediamine, in the presence of air as the oxidant, at 100°C for only 10 min under solvent-free conditions. This efficient methodology allowed the homocoupling of several terminal alkynes in moderate to excellent yields. Moreover, the same protocol was also applicable for the synthesis of some unsymmetrical 1,3-diynes through the cross-coupling reaction.

We established a new visible-light-mediated protocol for the regioselective βhydroxyselenylation of olefins, employing benzeneseleninic acid as substrate. Regarding a novel approach, the benzeneseleninic acid emerges as an efficient and affordable reagent to be used as an electrophilic selenium source that can be easily converted to selenium-based radical species under visible-light conditions. In this sense, the photocatalytically formed PhSe• radical can react directly with unsaturated substrates, including alkenes, to access a new C-Se bond and a carbon-centered radical intermediate, which finally is trapped by a hydroxyl radical species, delivering the βhydroxyselanyl compounds. Thus, despite the versatile utilities in organic synthesis, such as building blocks, the β-hydroxyselanyl compounds have demonstrated important biological activities. Based on that, we concentrated our efforts on developing a robust, effective, and environmentally benign methodology for their preparation. The optimal condition involves the reaction between styrene and 1.0 equivalent of phenylseleninic acid, in the presence of 5.0 mol% of eosin Y, as a cheap and easily available photocatalyst, with DMSO promoting the reaction medium. Satisfactorily, the system was irradiated with blue LED light for 2 h, to deliver the desired products in good yields.