We report here an alternative and tunable metal-free synthesis of benzo[b]chalcogenophenes via the electrophilic cyclization of 2-functionalized chalcogenoalkynes promoted by Oxone®. The use of mild reaction conditions, efficiency and generality are characteristics of this new approach, which was suitable to convert different diselenides and 2-functionalized chalcogenoalkynes into a total of twenty-two 2,3-bis-organochalcogenyl-benzo[b]chalcogenophenes, eighteen of which were synthesized for the first time. The new compound 2-(butylselanyl)-3-(phenylselanyl)benzofuran was used as a substrate in the Pd-catalyzed reaction with phenylacetylene to access the Sonogashira's coupling derivative in good yield.

A simple and practical protocol for the synthesis of 3-selanyl-benzo[b]furans mediated by the SelectFluor® reagent was developed. This novel methodology provided a greener alternative to generate 3-substituted-benzo[b]furans via a metal-free procedure under mild conditions. The intramolecular cyclization reaction was carried out employing an electrophilic selenium species generated in situ through the reaction between SelectFluor® and organic diselenides. The formation of this electrophilic selenium species (RSe-F) was confirmed by heteronuclear NMR spectroscopy, and its reactivity was explored.

A general methodology to access valuable 3-arylquinoxalin-2(1H)-ones was developed, by the reaction of α-keto acids with ortho-phenylenediamines in the presence of ammonium niobium oxalate (ANO) as a catalyst. The reactions were conducted in only 10 min under ultrasonic irradiation as an alternative energy source, affording water as the only co-product. A total of twenty-three different 3-arylquinoxalin-2(1H)-ones were selectively obtained in good to excellent yields by this atom-efficient protocol. Additionally, ¹H–¹⁵N HMBC experiments were used to reveal the regioisomerism of the obtained products.

Arylseleninic acids were used as an electrophilic selenium source in aromatic substitution reactions, using N,N-substituted anilines and indoles as nucleophiles at 70 °C for 6–15 h. A total of fourteen 4-selanylanilines and five 3-selanylindoles were selectively obtained in good to excellent yields. The starting benzeneseleninic acids are easily prepared from the respective diselenides, are bench stable and easy to handle, affording water as the only waste at the end of the reaction.