Selective Synthesis of Cyclic Dithiocarbonates Using Bis‐Benzimidazolate Salts as Multifunctional Catalysts

Abstract Cyclic dithiocarbonates of the type 1,3‐oxathiolane‐2‐thione were selectively and efficiently produced from the reaction between epoxides and CS 2 using disodium bis‐benzimidazolate salts as catalysts. We have designed and synthesized this group of three nucleophilic catalysts from the neutral forms of bis‐benzimidazole compounds ( BBE‐Me , BBE‐H and BBE‐NO 2 ), through simple and efficient procedures. All three catalysts, with aryl substituents possessing different electronic characteristics, were able to selectively catalyze the production of cyclic dithiocarbonates. BBE‐Me proved to be the most effective catalyst in the initial screening with 1,2‐epoxy‐3‐phenoxypropane, converting 95 % of the epoxide with 99 % of selectivity for the cyclic dithiocarbonate 1,3‐oxathiolane‐2‐thione. This catalyst was subsequently used to evaluate various reaction parameters and then several epoxides were selectively converted to the respective cyclic dithiocarbonates, under mild conditions, with a low catalyst loading, short reaction times, and in a solvent‐ and additive‐free system. A mechanistic proposal, supported by high‐resolution mass spectrometry, demonstrated for the first time that a nucleophilic catalyst in this system can simultaneously activate both CS 2 and the epoxide molecule.