Jorgensen-Hayashi organocatalyst/Bronsted acid-tethered multifunctional polymeric nanospheres for complex asymmetric multicomponent/multicatalysed organocatalysis: Heterogeneous Michael/Michael/aldol organocascade and [4+2] cycloaddition reactions

Heterogeneous multicomponent/multicatalysed asymmetric organocascade reaction in green manner is a challenging task owing to mass transfer limitation and cooperative catalysis of double or multiple catalysts. In this work, a novel type of nanosphere-supported multifunctional organocatalysts with high catalytic performances was developed towards meeting this challe-nge by the facile emulsion polymerization of organocatalyst (ProTMS or Pro) with styrene and acrylic acid (AA) in aqueous solution. The as-prepared Jorgensen-Hayashi organocatalyst/Bronsted acid-tethered polymeric nanospheres with large surface area, pore volume and high loading capacities of ProTMS and AA catalysts displayed the similar excellent catalytic performances as the corresponding homogeneous counterparts in heterogeneous three-component/triple Michael/Michael/aldol organocascade reaction (38-78%, > 19:1 dr and 95-99%ee) and [4+2]-type cycloaddition (76-86%,> 19:1 dr and 90-99%ee). Furthermore, the polymeric nanospheres could be quantitatively recovered from reaction mixture by centrifugation, reused without significant loss in catalytic performances and renovated with the upgraded efficiency in Michael/Michael/aldol organocascade reaction. The research findings of this study provided an important strategy and technology for the large-scale synthesis of optically active molecules with multiple stereocenters in a green manner. (C) 2017 Elsevier B.V. All rights reserved.