Direct covalent immobilizaion of chiral phosphines to hollow mesoporous polystyrene nanospheres (HMPNs) for efficient heterogeneous enantioselective [2+3] cycloaddition

• Published in: Applied catalysis. A, General General, 2023-09, Vol.666, p.119413, Article 119413
• Main Authors: Yin, Zuyun, He, Chuangchuang, Zhou, Yang, Liu, Jie, Zhang, Jianing, Ma, Xuebing
• Format: Article
• Language: English
• Subjects: Chiral phosphine; Covalent immobilization; Enantioselective [2+3] cycloaddition; Heterogeneous asymmetric organocatalysis; Hollow mesoporous polystyrene nanospheres
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2023.119413

Low-cost and convenient strategy for the direct covalent immobilizaion of chiral phosphines into structurally superior solid supports is desirable for efficient heterogeneous enantioselective catalysis. In this paper, a universal and convenient method for the direct covalent immobilization of chiral phosphines into HMPNs is developed via Friedel-Craft alkylation to fabricate supported chiral phosphines at a low cost. Using (S)-2,2´-bis(diphenylphosphino)-1,1´-binaphthyl [(S)-BINAP] and (R,R)-diphenylbis-[(o-anisyl)-methylenephosphine] [(R,R)-DIPAMP] as examples, the as-fabricated HMPNs-supported (S)-BINAP and (R,R)-DIPAMP, namely BINAP@HMPNs and DIPAMP@HMPNs, possess a well-shaped spherical morphology with hollow interior and thin mesoporous shell, enabling reactants to easily access to catalytic sites. In enantioselective [2+3] cycloaddition, DIPAMP@HMPNs exhibits good yields (70–86 %) with excellent enantioselectivities (94–98 %ee). Furthermore, DIPAMP@HMPNs shows a good mechanical stability of spherical morphology and mesoporous structure in its reuses. Moreover, the oxidation of DIPAMP leads to the gradual deactivation of DIPAMP@HMPNs including yield and enantioselectivity, which can be restored by the reduction of tetramethyldisiloxane (TMDS)/Ti(OiPr)4. [Display omitted] •Direct covalent immobilization of chiral phosphines.•Hollow porous polystyrene nanospheres as a support suitable for fast mass transfer.•Efficient heterogeneous enantioselective [2+3] cycloaddition.•Effective restoration of chiral phosphine oxide.