title: Hollow-shell-structured nanospheres: a recoverable heterogeneous catalyst for rhodium-catalyzed tandem reduction/lactonization of ethyl 2-acylarylcarboxylates to chiral phthalides.
abstract: 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.
authors.affiliation: Key Laboratory of Resource Chemistry of Ministry of Education, Shanghai Key Laboratory of Rare Earth Functional Materials, Shanghai Normal University, No.100 Guilin Rd., Shanghai 200234 (P. R. China), Fax: (+86) 2164322722.
authors.forename: Rui
authors.initials: R
authors.lastname: Liu
authors.forename: Ronghua
authors.initials: R
authors.lastname: Jin
authors.forename: Juzeng
authors.initials: J
authors.lastname: An
authors.forename: Qiankun
authors.initials: Q
authors.lastname: Zhao
authors.forename: Tanyu
authors.initials: T
authors.lastname: Cheng
authors.forename: Guohua
authors.initials: G
authors.lastname: Liu
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D046529:Microscopy, Electron, Transmission; D015394:Molecular Structure; D054118:Nanospheres; D010795:Phthalic Acids / Q000737:chemistry*; D012238:Rhodium / Q000737:chemistry*
chemical_list: D002264:Carboxylic Acids; D010795:Phthalic Acids; C032279:phthalic acid; D012238:Rhodium
keywords: asymmetric catalysis; heterogeneous catalysis; immobilization; silicates; supported catalysts