Hollow organic polymeric nano-bowls-supported BINOL-derived chiral phosphoric acid: enhanced catalytic performances in the enantioselective allylation of aromatic aldehydes

Abstract To improve the catalytic efficiency of expensive and versatile 1, 1′-binaphthol-derived chiral phosphoric acid with 2, 4, 6-tris(isopropyl)phenyl substituents and mass transfer of reactants in heterogeneous catalysis, a hollow organic polymeric nano-bowl was used as an effective catalyst support to anchor chiral phosphoric acid through the copolymerization of vinylated 1, 1′-binaphthol with 2, 4, 6-tris(isopropyl)phenyl substituents with styrene on the surface of polystyrene nanosphere core, etching polystyrene nanosphere by DMF and then phosphorylation by POCl 3 . From the comparative kinetic investigation on the reaction rate of reactant in the asymmetric allylboration of 4-chlorobenzaldehyde with allylboronic pinacol ester, the as-fabricated hollow organic polymeric nano-bowl-supported chiral phosphoric acid displayed higher catalytic rates than ever-reported similar catalyst and possessed a constant catalytic rate (0.031 mol L −1  h −1 ) during the whole process. The expanded scope of aromatic aldehydes further proved that the hollow organic polymeric nano-bowl-supported chiral phosphoric acid was more highly active and enantioselective owing to its thin shell thickness (18 nm) and hollow structure. Due to the constant phosphorus content and well-shaped morphology of the 6th-reused catalyst, the yield of ( R )-1-phenylbut-3-en-1-ol (95%) with a slightly lowered enantioselectivity (94% ee) remained constant in the sixth run. Moreover, the lowered enantioselectivity of the 6th-reused catalyst could be restored by hydrochloric acid to achieve its original enantioselectivity (96% ee), and the prothetic hollow organic polymeric nano-bowl-supported chiral phosphoric acid could effectively promote the asymmetric allylboration reaction in high yields (92–95%) with excellent enantioselectivities (94–96% ee) for another six cycles.