Herein, we report the organocatalytic asymmetric synthesis of two β-ketoenamine-linked chiral covalent organic frameworks (CCOFs), namely (Λ)-TpPEA and (Δ)-TpPEA, incorporating salphen building blocks in their skeletons under ambient conditions. This strategy employs a chiral 2-methylpyrrolidine catalyst to induce propeller chirality during polycondensation of prochiral monomers, circumventing the need for preformed chiral building blocks. The resulting chiral covalent organic frameworks possess abundant chiral salphen ligand sites, into which manganese ions can be readily incorporated via coordination, affording Mn(III)-loaded CCOFs. These materials serve as recyclable heterogeneous catalysts for the aqueous-phase asymmetric sulfoxidation reaction, achieving up to 99% conversion and 96% enantiomeric excess (ee). This work establishes a green platform for aqueous-phase asymmetric catalysis, revealing the crucial role of chiral inorganic–organic hybrid frameworks in governing enantioselectivity.
Li et al. (Sat,) studied this question.