Direct and Post-Synthesis Incorporation of Chiral Metallosalen Catalysts into Metal-Organic Frameworks for Asymmetric Organic Transformations

Two chiral porous metal-organic frameworks (MOFs) were constructed from [VO(salen)]-derived dicarboxylate and dipyridine bridging ligands. After oxidation of V-IV to V-V, they were found to be highly effective, recyclable, and reusable heterogeneous catalysts for the asymmetric cyanosilylation of aldehydes with up to 95%ee. Solvent-assisted linker exchange (SALE) treatment of the pillared-layer MOF with [Cr(salen)Cl]- or [Al(salen)Cl]-derived dipyridine ligands led to the formation of mixed-linker metallosalen-based frameworks and incorporation of [Cr(salen)] enabled its use as a heterogeneous catalyst in the asymmetric epoxide ring-opening reaction.