A Cascade Polymerization Platform from Carbon Monoxide and Elemental Chalcogens

The development of efficient synthetic strategies to access chalcogen-rich functional polymers from readily available feedstocks represents a challenge in polymer chemistry. Herein, we report a versatile cascade polymerization strategy that utilizes carbon monoxide (CO) as a general C1 feedstock for the in situ generation of carbonyl selenide (COSe) and carbonyl sulfide (COS) from elemental selenium and sulfur, respectively. This metal-free approach, mediated by a Lewis pair catalytic system, enables the chemoselective synthesis of 15 new poly(selenocarbonate)s from various epoxides under ambient conditions, all featuring a dominant [-C(═O)Se-] backbone structure. Remarkably, the reaction pathway exhibits a temperature-dependent chemoselectivity switch: elevated temperatures selectively direct the transformation toward either cyclic selenocarbonates or alkenes through a reductive deoxygenation pathway. Simultaneously, the in situ generated COS preferentially affords cyclic thiocarbonates, which subsequently undergo efficient decarbonylative ring-opening polymerization to produce well-defined, high-molecular-weight poly(thioether)s. This work establishes a general platform for converting elemental chalcogens and CO into functional polymeric materials through cascade catalysis, expanding the synthetic toolbox for chalcogen-containing polymers with potential applications in optics and materials science.