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Titolo:
Catalytic asymmetric heterogeneous aziridination of styrene using CuHY: effect of nitrene donor on enantioselectivity
Autore:
Taylor, S; Gullick, J; McMorn, P; Bethell, D; Page, PCB; Hancock, FE; King, F; Hutchings, GJ;
Indirizzi:
Cardiff Univ, Dept Chem, Cardiff CF10 3TB, S Glam, Wales Cardiff Univ Cardiff S Glam Wales CF10 3TB ardiff CF10 3TB, S Glam, Wales Univ Liverpool, Dept Chem, Leverhulme Ctr Innovat Catalysis, Liverpool L693BX, Merseyside, England Univ Liverpool Liverpool Merseyside England L69 3BX , Merseyside, England Loughborough Univ Technol, Dept Chem, Loughborough LE11 3TU, Leics, England Loughborough Univ Technol Loughborough Leics England LE11 3TU cs, England Synetix, Billingham TS23 1LB, Teesside, England Synetix Billingham Teesside England TS23 1LB TS23 1LB, Teesside, England
Titolo Testata:
JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
fascicolo: 9, , anno: 2001,
pagine: 1714 - 1723
SICI:
1472-779X(200109):9<1714:CAHAOS>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
LIGAND-ACCELERATED CATALYSIS; CHIRAL LIGANDS; OLEFINS; COMPLEXES; EPOXIDATION; ALKENES; CYCLOPROPANATION; IODOSYLBENZENE; PORPHYRIN; MANGANESE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
40
Recensione:
Indirizzi per estratti:
Indirizzo: Hutchings, GJ Cardiff Univ, Dept Chem, POB 912, Cardiff CF10 3TB, S Glam, Wales Cardiff Univ POB 912 Cardiff S Glam Wales CF10 3TB am, Wales
Citazione:
S. Taylor et al., "Catalytic asymmetric heterogeneous aziridination of styrene using CuHY: effect of nitrene donor on enantioselectivity", J CHEM S P2, (9), 2001, pp. 1714-1723

Abstract

The copper-catalysed aziridination of styrene with copper-exchanged zeolite Y (CuHY) and copper(II) triflate (trifluoromethanesulfonate) (Cu(OTf)(2))as catalysts is described in detail. Two nitrene donors, [N-(p-tolylsulfbnyl)-imino)]phenyliodinane (PhI=NTs) and [N-(p-nitrophenylsulfonyl)imino]phenyliodinane (PhI=NNs) are compared. Modification of the catalyst with bis(oxazolines) affords enantioselective catalysts and a range of chiral bis(oxazolines) has been studied. The ratio of nitrene donor to styrene is shown to bean important factor controlling, both the yield and ee of aziridine formed. The best results are obtained with PhI=NNs;ee, greater than or equal to 90%, together with high yields (greater than or equal to 85%), can readily be achieved with this nitrene donor using acetonitrile as solvent. Addition of the nitrene donor over a period of time, rather than all at the startof the reaction, is shown to enhance the yield of the aziridine but the eeis significantly decreased for both the homogeneous and the heterogeneous catalysts. Experiments in which the breakdown products of the nitrene donor, iodobenzene and the corresponding sulfonamide, are added at the start of the reaction show that a complex interplay exists at the copper active sitebetween the reactants, products, chiral modifier and the solvent. However,the heterogeneous catalyst, CuHY, is found to give enhanced enantioselection for a range of bis(oxazolines) compared to the homogeneous catalyst, andthe effect is considered to be due to the confinement of the catalyst within the micropores of the zeolite.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 16:01:42