Multifunctional hollow mesoporous organic polymeric nanospheres (HMOPs) as effective heterogeneous catalysts with enhanced activity in green asymmetric organocatalysis

Abstract Based on the unique advantages including hollow interior, mesoporous shell, well-defined morphology and good compatibility with organic reactants, the first controllable fabrication of hollow mesoporous organic polymeric nanospheres (HMOPs) with pure intriguing mesopores was developed using low-cost and commonly available materials via metal ion adsorption in outer shell, in-situ forming metal hydroxide or phosphate expansion and removal of templates. After being sulfonated by ClSO 3 H, the resulting Co(OH) 2 -templated HMOPs with the highest acid exchange capacity (2.67 mmol g −1 ) could effectively immobilize versatile 9-amino(9- deoxy) epi -cinchonidine organocatalyst (0.98 mmol g −1 ) via acid-base interaction without multi-step chemical modification. In the green asymmetric aldol addition and double-Michael organocascade reaction, the mesopore- abundant HMOPs exhibited significantly higher catalytic performances in yields, diastereoselectivities and enantioselectivities than mesopore-deficient HNs due to the ordered mesoporous (2–15 nm), amphipathic shell and hollow interior. Based on the unchanged spherical morphology and hollow mesoporous structure, HMOPs was proved to possess a good mechanical stability in recycled processes.