Heterogeneous Epoxide Carbonylation by Cooperative\nIon-Pair Catalysis in Co(CO)4–‑Incorporated\nCr-MIL-101

Despite\nthe commercial desirability of epoxide carbonylation to\nβ-lactones, the reliance of this process on homogeneous catalysts\nmakes its industrial application challenging. Here we report the preparation\nand use of a Co­(CO)4–-incorporated Cr-MIL-101\n(Co­(CO)4⊂Cr-MIL-101, Cr-MIL-101 = Cr3O­(BDC)3F, H2BDC = 1,4-benzenedicarboxylic acid)\nheterogeneous catalyst for the ring-expansion carbonylation of epoxides,\nwhose activity, selectivity, and substrate scope are on par with those\nof the reported homogeneous catalysts. We ascribe the observed performance\nto the unique cooperativity between the postsynthetically introduced\nCo­(CO)4– and the site-isolated Lewis\nacidic Cr­(III) centers in the metal–organic framework (MOF).\nThe heterogeneous nature of Co­(CO)4⊂Cr-MIL-101 allows\nthe first demonstration of gas-phase continuous-flow production of\nβ-lactones from epoxides, attesting to the potential applicability\nof the heterogeneous epoxide carbonylation strategy.