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Transition-metal-catalyzed asymmetric reactions have been demonstrated to be powerful methods for enantioselective construction of various optically pure compounds. The development of ordered mesoporous silica-supported chiral transition-metal-based catalysts and the exploration of their applications represent important progress in green chemistry since such an approach enables an eco-friendly and sustainable catalytic process. In this review, we focus on recent advances in the preparation of ordered mesoporous silica-supported chiral transition-metal-based catalysts and their applications in enantioselective transformations. Firstly, we provide a brief introduction to the modification of ordered mesoporous silicas. We then present in detail, the application of transition-metal-functionalized ordered mesoporous silicas for enantioselective transformations according to various types of reactions. Lastly, prospects for the further development of this research area are discussed. [ABSTRACT FROM AUTHOR]

An important challenge in asymmetric cascade reactions is solving the intrinsic incompatibility of two types of distinct organometallic complexes that participate in a one-pot reaction. Herein, we develop an organoruthenium-/organopalladium-bifunctionalized periodic mesoporous organosilica and realize one-pot cascade reactions of Ru-catalyzed asymmetric transfer hydrogenation and Pd-relay-catalyzed cross-coupling of haloacetophenones and arylboronic acids to various chiral biaryl alcohols, with quantitative conversions and up to 98 % enantioselectivity in an aqueous medium. This characteristics is attributed to the site-isolated, uniformly distributed, well-defined single-site palladium and ruthenium active species. Furthermore, the heterogeneous catalyst is conveniently recovered and reused repeatedly for eight times without loss of its catalytic activity, showing particular attractiveness for practicing organic transformation. [ABSTRACT FROM AUTHOR]

Chiral organorhodium-functionalized hollow-shell-structured nanospheres were prepared by immobilization of a chiral N-sulfonylated diamine-based organorhodium complex within an ethylene-bridged organosilicate shell. Structural analysis and characterization reveal its well-defined single-site rhodium active center, and transmission electron microscopy images reveal a uniform dispersion of hollow-shell-structured nanospheres. As a heterogenous catalyst, it exhibits excellent catalytic activity and enantioselectivity in synthesis of chiral phthalides by a tandem reduction/lactonization of ethyl 2-acylarylcarboxylates in aqueous medium. The high catalytic performance is attributed to the synergistic effect of the high hydrophobicity and the confined chiral organorhodium catalytic nature. The organorhodium-functionalized nanospheres could be conveniently recovered and reused at least 10 times without loss of catalytic activity. This feature makes it an attractive catalyst in environmentally friendly organic reactions. The results of this study offer a new approach to immobilize chiral organometal functionalities within the hollow-shell-structured nanospheres to prepare materials with high activity in heterogeneous asymmetric catalysis. [ABSTRACT FROM AUTHOR]