Silica–Polystyrene Hybrid Core/Shell Microparticles of Rhodium–Chiral Diene Complexes as Catalysts for Asymmetric 1,4-Addition Reactions

Abstract

Heterogeneous catalysts for fine chemical synthesis play a crucial role in establishing an efficient chemical process. Immobilization of homogeneous catalysts is an important method for the preparation of heterogeneous catalysts; however, it is often accompanied by a loss of catalytic activity due to limited mass transport in the support matrix. Here, we have designed core/shell type polystyrene shell supports on silica with low degrees of cross-linking to improve accessibility to reaction sites. It was found that rhodium–chiral diene complexes on core/shell particles showed higher catalytic activity in comparison those on conventional supports and even better catalytic activity than the corresponding homogeneous catalyst in asymmetric 1,4-addition reactions. Our results may provide a general strategy to obtain many other heterogeneous catalysts with high activities.

Determination of accessibility and spatial distribution of chiral Rh diene complexes immobilized on SBA-15 via phosphine-based solid-state NMR probe molecules

“…1,2-and 1,4-adducts, cycloaddition and rearrangement products. [17][18][19] In addition, asymmetric Rh diene complexes immobilized on various supports [20][21][22][23] and Rh diene complexes under liquid 24,25 and solid confinement 26,27 have been reported. In silica pores adsorbed hydridocarbonyltris(triphenylphosphine)rhodium (HRh(CO) (PPh 3 ) 3 ) in PPh 3 and solvent showed modified reaction rates and regioselectivities in hydroformylation of propene.…”

Tethering chiral Rh diene complexes inside mesoporous solids: experimental and theoretical study of substituent, pore and linker effects on asymmetric catalysis

“…Among the various chiral metal complexes, that have been studied in asymmetric heterogeneous catalysis so far, chiral Rh diene complexes 40 immobilized on solid supports are an emerging field. While work employing polystyrene-based polymer-incarcerated Rh nanoparticles, 41,42 polystyrene, 43,44 silica-polystyrene core/shell particles 45 and diene copolymers, 46 respectively focused on catalyst recycling, few studies dealing with MOFs, 47 COFs, 48 mesoporous silica 49 and silica inverse opals 50 started to examine pore specific effects on Rh diene catalysis. For example, we were able to selectively achieve inner pore functionalization of mesoporous silica SBA-15 with chiral Rh norbornadiene complexes via outer pore protection and selective inner pore Cu-catalyzed click reaction.…”

Towards Automated Microfluidic‐based Platforms: Optimizing Hydrogenation Efficiency of Nitrobenzene through π–π Interactions in Pd Nanoparticles on Covalent Organic Frameworks

“…It is technically challenging to operate without handling expertise and specially‐designed program. Concerns of catalyst loading and packing become even more apparent when heterogeneous nanocatalysts are present in the microdevice [24, 25] . Therefore, compared with its batch counterpart, the interplay between reactor internals and nanocatalysts in microplatform remains an open question.…”