Halogen anion is oxidized to molecular halogens, halogen cations or halogen radicals at the anode, which combines with substrates to provide different products.

An efficient electrochemical transformation of structurally diverse sulfonyl hydrazides and thiols into thiosulfonates in the presence of ammonium iodide as redox catalyst and electrolyte in acetonitrile at ambient temperature is reported. Transition metal- and oxidant-free conditions are the striking features of this protocol. The in vitro cytotoxicity of all compounds is evaluated by MTT assay against four human cancer cell lines. The results reveal that 3ac and 3ag exhibit potential inhibitory activity against tumor cells. Furthermore, 3ag inhibits cell migration ability and tubulin polymerization in T-24 cells, leading to cell cycle arrest and apoptosis.

Owing to the inert nature of the pyridine ring and high activity of iminyl radicals, the reaction between pyridine and iminyl radicals remains a significant challenge. In this paper, we report the synthesis of sulfide imidazo[1,2-a]pyridines from vinyl azides, thiophenols, and pyridines via a radical [3 + 2] cycloaddition. Promoting inert pyridine and highly active iminyl radicals to participate in this intermolecular cycloaddition process is the striking feature of this protocol. The excellent antitumor activity of the prepared sulfide imidazopyridine scaffold demonstrated the synthetic utility of the developed synthetic protocol.

A photocatalyst-free visible-light-promoted sulfenylation of quinoxalinones with thiols via cross-dehydrogenative coupling was developed. This protocol allowed the direct formation of diverse 3-sulfenylquinoxalin-2(1H)-ones under metal- and catalyst-free conditions and using air (O₂) as an oxidant. Furthermore, a range of readily accessible thiols and quinoxalin-2(1H)-ones was applied in this coupling, resulting in an attractive process of accessing 3-substituted quinoxalinones.