Unprecedented light-induced oxidant and metal-free tandem radical cyclization–trifluoromethylation and dehydrogenative oxygenation of 1,6-enynes have been achieved using a photoredox catalyst, CF3SO2Na, and water as the oxygen source.

Regenerable, multifunctional ebselenol antioxidants were prepared that could quench peroxyl radicals more efficiently than α-tocopherol. These compounds act as better mimics of the glutathione peroxidase enzymes than ebselen. Production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in human mononuclear cells was considerably decreased upon exposure to the organoselenium compounds. At a concentration of 25 μm, the ebselenol derivatives showed minimal toxicity in pre-osteoblast MC3T3 cells.

A series of diaryl ditellurides with and without coordinating amino/imino groups are synthesized by using either the Grignard route or the heteroatom-directed aromatic lithiation route. The chiral ditelluride (R),(R)-bis[2-(4-ethyl-2-oxazolinyl)phenyl] ditelluride is synthesized in an enantiomerically pure form by stereoselective ortho-lithiation. The thiol peroxidase activity of the ditellurides is studied by using H2O2 as a substrate and PhSH as a cosubstrate. The initial rates for the reduction of H2O2 catalyzed by diaryl ditellurides are much higher than those catalyzed by the corresponding diselenides. A comparison of the activities between various diorganyl ditellurides and diselenides shows that the presence of basic amino groups in the close proximity of tellurium enhances the reduction rates and the effect of amino groups on the activity is more pronounced in the case of ditellurides as compared to the corresponding diselenides. On the other hand, a correlation between the strength of Te···N intramolecular interactions and thiol peroxidase activity reveals that the strong Te···N interactions reduce the thiol peroxidase activity of amino/imino-substituted ditellurides. A plot of Te···N distances against 125Te NMR chemical shifts shows a linear correlation.

A transition-metal-free synthetic method has been developed for the synthesis of unsymmetrical diaryl chalcogenides (S, Se, and Te) from diaryl dichalcogenides and arenes under oxidative conditions by using potassium persulfate at room temperature. Variously substituted arenes such as anisole, thioanisole, diphenyl ether, phenol, naphthol, di- and trimethoxy benzenes, xylene, mesitylene, N,N-dimethylaniline, bromine-substituted arenes, naphthalene, and diaryl dichalcogenides underwent carbon-chalcogen bond-forming reaction to give unsymmetrical diaryl chalcogenides in trifluoroacetic acid. To understand the mechanistic part of the reaction, a detailed in situ characterization of the intermediates has been carried out by (77)Se NMR spectroscopy by using diphenyl diselenide as the substrate. (77)Se NMR study suggests that electrophilic species ArE(+) is generated by the reaction of diaryl dichalcogenide with persulfate in trifluoroacetic acid. The electrophilic attack of arylchalcogenium ion on the arene may be responsible for the formation of the aryl-chalcogen bond.