Multiple Functionalized Hyperbranched Polyethoxysiloxane Promotes Suzuki Coupling Asymmetric Transfer Hydrogenation One‐Pot Enantioselective Organic Transformations

Abstract

AbstractUtilization of amphiphilic poly(ethylene glycol) monomethyl ether modified hyperbranched polyethoxysiloxane as a support for the construction of bifunctional heterogeneous catalysts enables a highly efficient catalytic system thanks to its amphiphilic nature in aqueous organic transformations. Herein, through a three‐component self‐assembly procedure, we incorporate palladium/phosphine and chiral ruthenium/diamine functionality within poly(ethylene glycol) monomethyl ether modified hyperbranched polyethoxysiloxane, fabricating a multiple functionalized polyethoxysiloxane based mesoporous material. Structural analyses and characterizations disclose that well‐defined dual single‐site active centers are distributed uniformly within monodisperse mesoporous silica nanoparticles. As a bifunctional heterogeneous catalyst, this material performs the one‐pot enantioselective tandem reaction of Pd‐catalyzed Suzuki cross‐coupling and Ru‐catalyzed asymmetric transfer hydrogenation, affording various chiral biaryl alcohols with high yields and up to 99 % enantioselectivity. Furthermore, the catalyst can be recovered and recycled eight times without loss of its catalytic activity, demonstrating the practicability of the preparation of optically pure biaryl alcohols in one‐pot organic transformation.