Imidazolium‐Based Organic–Inorganic Hybrid Silica as a Functional Platform Dramatically Boosts Chiral Organometallics Performance in Asymmetric Catalysis

Abstract

Phase‐transfer featured, imidazolium‐based, organic‐inorganic hybrid silica represents a novel functionalized platform with particularly attractive features in asymmetric catalysis. Herein, we report a chiral organorhodium‐functionalized heterogeneous catalyst. As demonstrated in the studies, it displays comparable or higher catalytic activity and enantioselectivity than its homogeneous counterpart in asymmetric transformations. The superior catalytic performance is attributed to the synergistic effect of the salient imidazolium phase‐transfer character and the confined chiral organorhodium catalytic nature in addition to the merits of mesoporous silica. Furthermore, it is more robust than other silica‐derived heterogeneous systems and can be conveniently recovered and reused at least 10 times without loss of its catalytic efficiency. These features render the catalyst particularly attractive in practice of organic synthesis. The outcomes from the study clearly show that the strategy described here offers a general approach to immobilization of chiral ligand‐derived silane onto the phase‐transfer featured imidazolium‐based organic‐inorganic hybrid silica materials with significant improving catalyst efficiency.

An imidazolium-based organopalladium-functionalized organic–inorganic hybrid silica promotes one-pot tandem Suzuki cross coupling–reduction of haloacetophenones and arylboronic acids

“…As an effort to develop highly efficient heterogeneous catalysts, [20][21][22][23][24][25] in this contribution, we utilize the benefits of an imidazolium-based organic-inorganic hybrid silica (IBOIHS) and develop an organopalladium-functionalized heterogeneous catalyst PdPPh 2 -IBOIHS (3), consisting of uniformly distributive, well-defined confined organopalladium active species within its imidazolium-based silicate network. As expected, the imidazolium functionality and the well-defined confined organopalladium active species within IBOIHS can promote synergistically its catalytic performance.…”

Positioning growth of scalable silica nanorods on the interior and exterior surfaces of porous composites

“…Perhaps one of the most promising applications, which capitalizes on recent achievements in functionalizing silica surfaces and related hybrid materials, is bio-mimic materials. 37 Separation membranes with hierarchical structures would be another prospective eld. 36 Furthermore, the dramatic increase in specic surface area would be highly desirable in new types of adsorbents or catalyst materials.…”

“…36 Furthermore, the dramatic increase in specic surface area would be highly desirable in new types of adsorbents or catalyst materials. 37 Separation membranes with hierarchical structures would be another prospective eld. As an example, with silica nanorods grown on one-side of a porous scaffold, a one-piece integrated membrane could be fabricated, reducing the probability of delamination of adjacent layers.…”

Transition-metal-functionalized ordered mesoporous silicas: an overview of sustainable chiral catalysts for enantioselective transformations

“…Similarly, by utilizing an organic-inorganic hybrid silica as a support, it could also construct a chiral Rh-based heterogeneous catalyst 24. 68 As shown in Scheme 19, the direct post-grafting of chiral TsDPENderived siloxane onto an imidazolium-based organicinorganic hybrid silica followed by the complexation with (Cp*RhCl 2 ) 2 leads to a high efficient heterogeneous catalyst 24, in which an imidazolium-functionality in catalyst 24 could substitute Bu 4 NBr to play a phase-transfer role to boost the catalytic performance in the ATH reactions of various aromatic methyl ketones, cyclic and acyclic ketones in aqueous medium.…”