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In an enantioselective reaction, we expect to obtain two types of chiral products through a controllable strategy in asymmetric catalysis. Herein, we develop Ru-catalysed asymmetric transfer hydrogenation of α-ketoimides to realise an enantioselective construction of chiral α-hydroxy imides or chiral α-hydroxy esters. The transformation of α-ketoimides catalysed by ( S, S)-[RuCl(η6-mesitylene)diamine] can afford various chiral α-hydroxy imides with high yields and enantioselectivities, whereas that catalysed by ( S, S)-[RuCl(η6-hexamethylbenzene)diamine] gives the desirable chiral α-hydroxy esters through a slight adjustment of the reaction conditions. The method described here is a controllable organic transformation with sodium formate as a hydrogen source under mild reaction conditions, and the benefit of this transformation is that various chiral α-hydroxy imides or α-hydroxy esters can be obtained selectively from α-ketoimides. [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]