Synergistic catalysis of one-pot cascade reactions by acidic and basic binary porous polymers

Acidic and basic porous polymers were facilely prepared through the radical copolymerization of target monomers and the crosslinker divinylbenzene (DVB), respectively. Combination of these polymers endowed highly efficient, heterogeneous recyclable acid-base binary catalysts for cascade deacetalization-Knoevenagel reaction, offering high yield and stable reusability. Binary polymers with strong acid sites and superior base sites afforded an unprecedented turnover frequency (TOF) in the condensation of benzaldehyde dimethylacetal and nitriles (285 h ⁻¹ for malononitrile and 57 h ⁻¹ for inert methylene substrate ethyl cyanoacetate). The excellent synergistically catalytic performance was ascribed to the unique self-protection effect of the in-situ formed acid and base sites embedded in the polymeric network. This study provided a facile, versatile and efficient strategy towards acid-base bifunctional heterogeneous catalysts by combining acidic and basic porous polymers.