Poly(thioether)s from Closed-System One-Pot Reaction of Carbonyl Sulfide and Epoxides by Organic Bases

The synthesis of poly(thioether), a highly desired sulfur-containing polymer, is still a key challenge. Herein, we report a simple and facile approach to poly(thioether)s by closed-system one-pot reaction of carbonyl sulfide (COS) and epoxides. This route underwent the coupling reaction of COS with epoxides, followed by decarboxylative ring-opening polymerization (ROP) of the generated mixed cyclic thiocarbonates with releasing of CO₂ and a little bit of COS. Organic base was used as catalyst and initiator in the two steps, respectively. The oxygen/sulfur exchange reaction was driven by successive regioselective elementary reactions and spontaneous releasing of CO₂ (COS), leading to the sulfur atom of COS transferring to poly(thioether)s, which was well demonstrated by DFT studies. This work provides an easy-to-handle, metal-free route to poly(thioether)s bearing diverse structures by using readily available chemicals.