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Hollow‐Shell‐Structured Nanospheres: A Recoverable Heterogeneous Catalyst for Rhodium‐Catalyzed Tandem Reduction/Lactonization of Ethyl 2‐Acylarylcarboxylates to Chiral Phthalides
Author(s) -
Liu Rui,
Jin Ronghua,
An Juzeng,
Zhao Qiankun,
Cheng Tanyu,
Liu Guohua
Publication year - 2014
Publication title -
chemistry – an asian journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 106
eISSN - 1861-471X
pISSN - 1861-4728
DOI - 10.1002/asia.201301543
Subject(s) - catalysis , rhodium , dispersion (optics) , tandem , aqueous solution , chemistry , shell (structure) , materials science , chemical engineering , combinatorial chemistry , organic chemistry , composite material , physics , optics , engineering
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.