Enantioselective cyclopropanation and aziridination catalyzed by copper(II) bis(oxazoline) anchored onto mesoporous materials
authors Albuquerque, H; Carneiro, L; Carvalho, AP; Pires, J; Silva, AR
nationality International
journal POLYHEDRON
author keywords Homogeneous catalysis; Heterogeneous catalysis; Asymmetric catalysis; Immobilization; Mesoporous materials
keywords ASYMMETRIC HETEROGENEOUS AZIRIDINATION; CARBON REPLICAS; COMPLEXES; LIGANDS; SUPPORT; STYRENE; SILICAS; OLEFINS; IMMOBILIZATION; ADSORPTION
abstract The preparation of multipurpose asymmetric heterogeneous catalysts based on the immobilization of expensive privileged chiral ligands onto porous supports is essential for their use in industry. The benchmark cyclopropanation of styrene has been performed using a copper(II) complex of a commercial chiral bis(oxazoline) anchored onto ordered mesoporous silica materials (including SBA-15) and their carbon replicas (including CMK-3), and for the first time, we also report on the asymmetric aziridination of styrene by anchored copper(II) bis(oxazoline). All the composites prepared were active and enantioselective in these two organic transformations. In the cyclopropanation of styrene, the best heterogeneous catalyst gave higher enantioselectivities and TON than in the corresponding homogeneous phase reactions. In the aziridination of styrene the enantioselectivities for the best heterogeneous catalysts were similar to the propylated bis(oxazoline). The mesoporous silica, prepared by a straightforward one-pot procedure, was always among the best supports for the functionalized bis(oxazoline) in all the asymmetric processes studied. However its carbon replica was not a good support for the outcome of these asymmetric transformations, always yielding the lowest enantioselectivities. Once again the mesoporous materials surface properties were an important factor for the uniform distribution of the homogeneous catalyst, as well as for the course of the asymmetric organic reactions, together with the pore size. The best results presented herein are comparable to the ones reported for copper(II) bis (oxazoline) (2) immobilized onto other types of porous supports. (C) 2014 Elsevier Ltd. All rights reserved.
publisher PERGAMON-ELSEVIER SCIENCE LTD
issn 0277-5387
year published 2014
volume 79
beginning page 315
ending page 323
digital object identifier (doi) 10.1016/j.poly.2014.05.025
web of science category Chemistry, Inorganic & Nuclear; Crystallography
subject category Chemistry; Crystallography
unique article identifier WOS:000340313800037
  ciceco authors
  impact metrics
journal analysis (jcr 2017):
journal impact factor 2.067
5 year journal impact factor 1.870
category normalized journal impact factor percentile 54.594
dimensions (citation analysis):
altmetrics (social interaction):



 


Apoio

1suponsers_list_ciceco.jpg