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Semi-heterogeneous asymmetric organocatalysis: Covalent immobilization of BINOL-derived chiral phosphoric acid (TRIP) to polystyrene brush grafted on SiO2 nanoparticles
Journal of Catalysis ( IF 7.3 ) Pub Date : 2022-11-07 , DOI: 10.1016/j.jcat.2022.10.021
Shan Li, Jianing Zhang, Shaoqi Chen, Xuebing Ma

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 SiO2 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.



中文翻译:

半非均相不对称有机催化:将 BINOL 衍生的手性磷酸 (TRIP) 共价固定到接枝在 SiO2 纳米颗粒上的聚苯乙烯刷上

减少传质和昂贵的手性有机催化剂的繁琐固定是在非均相不对称有机催化中大规模合成光学活性分子的两个瓶颈。在这里,通过一锅法将 BINOL 衍生的磷酸 (TRIP) 锚定到接枝在 SiO 2纳米颗粒上的聚苯乙烯 (PS) 刷上,实现了准均相有机催化,由于 TRIP 锚定的 PS 刷的开放式拉伸,有效改善了传质在甲苯中。与 PS 支持的 TRIP 相比,PS 刷使 TRIP 能够以显着更高的产率和对映选择性催化不对称烯丙基化,并且在 产量略高于同质 TRIP。PS刷的较稀疏的接枝密度更有利于PS刷的溶胀,导致反应物从PS刷的顶部到末端的传质更快。总体而言, TRIP 与 PS 刷的一锅锚定结合了均相和非均相有机催化的优点,为解决多相不对称有机催化中的两个瓶颈提供了理想的策略。

更新日期:2022-11-10
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