Semi-heterogeneous asymmetric organocatalysis: Covalent immobilization of BINOL-derived chiral phosphoric acid (TRIP) to polystyrene brush grafted on SiO2 nanoparticles.

[Display omitted] • Bridging the gap between homogeneous and heterogeneous asymmetric organocatalysis. • Effective strategy for solving bottlenecks in heterogeneous asymmetric organocatalysis. • One-pot covalent immobilization of TRIP to PS brush grafted on SiO 2 nanoparticles. • Fast mass transfer due to the open stretching structure of anchored TRIP in toluene. • Sparse grafting density of PS brush in favor of the fast mass transfer of reactants. Reduced mass transfer and tedious immobilization of expensive chiral organocatalyst are two bottlenecks for the large-scale synthesis of optically active molecules in heterogeneous asymmetric organocatalysis. Here, a quasi-homogeneous organocatalysis is achieved by anchoring BINOL-derived phosphoric acid (TRIP) to polystyrene (PS) brush grafted on SiO 2 nanoparticles via one-pot, effectively improving mass transfer due to the open stretching of TRIP-anchored PS brush in toluene. The PS brush enables TRIP to catalyze asymmetric allylation in significantly higher yields and enantioselectivities than PS-supported TRIP, and in slightly higher yields than homogeneous TRIP. The sparser grafting density of PS brush is more conducive to the swelling of PS brush, leading to the faster mass transfer of reactants from the top to end of PS brush. Overall, the one-pot anchoring of TRIP to PS brush combines the advantages of homogeneous and heterogeneous organocatalysis, providing an ideal strategy for solving the two bottlenecks in heterogeneous asymmetric organocatalysis. [ABSTRACT FROM AUTHOR]