A chiral porous metallosalan-organic framework containing titanium-oxo clusters for enantioselective catalytic sulfoxidation

A chiral porous zeolite-like metal-organic framework is constructed by using mixed ligands of dipyridyl-functionalized chiral Ti(salan) and biphenyl-4,4'-dicarboxylate. The framework containing salan-bound Ti4O6 clusters consists of both hydrophobic and amphiphilic mesocages and is shown to be an efficient and recyclable heterogeneous catalyst for the oxidation of thioethers to sulfoxides by aqueous H2O2 (up to 82% ee), displaying markedly enhanced enantioselectivity over the homogeneous catalyst by providing a cavity confinement effect. This work highlights the potential of significantly improving enantioselectivity of homogeneous catalysts by using MOFs as support structures.