Emerging organosulfonium electrophiles as unique reagents for carbonsulfur bond formation: Prospects in synthetic chemistry of organosulfur compounds

Carbon-sulfur (C-S) bond formation is one of the important synthetic routes in organic chemistry. Among sulfur sources for C-S bond formation, organosulfur cations (RS⁺) and their synthetic equivalents are unique reagents. These cationic sulfur species are easily prepared as compared with the oxonium analogues, because of their low ionization potentials. This review describes various synthetic methods for C-S bond formation, mainly focusing on electrophilic reactions, addition to olefins, and substitution to aromatic rings. A breakthrough has been anticipated for RS⁺ electrophiles, based on their versatile utility in aromatic polymer synthesis.