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Titolo:
Palladium complexes containing bis(oxazolines): stoichiometric versus catalytic allylic alkylation
Autore:
Gomez, M; Jansat, S; Muller, G; Maestro, MA; Saavedra, JM; Font-Bardia, M; Solans, X;
Indirizzi:
Univ Barcelona, Dept Quim Inorgan, E-08028 Barcelona, Spain Univ Barcelona Barcelona Spain E-08028 Inorgan, E-08028 Barcelona, Spain Univ Coruna, Fac Ciencias, Serv Xerais Apoio Invest, E-15071 A Coruna, Spain Univ Coruna A Coruna Spain E-15071 Apoio Invest, E-15071 A Coruna, Spain Univ Barcelona, Dept Cristallog Mineral & Diposits Minerals, E-08028 Barcelona, Spain Univ Barcelona Barcelona Spain E-08028 inerals, E-08028 Barcelona, Spain
Titolo Testata:
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
fascicolo: 9, , anno: 2001,
pagine: 1432 - 1439
SICI:
1472-7773(2001):9<1432:PCCBSV>2.0.ZU;2-6
Fonte:
ISI
Lingua:
ENG
Soggetto:
ASYMMETRIC CATALYSIS; ENANTIOSELECTIVE CATALYSIS; CHIRAL LIGANDS; DERIVATIVES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
30
Recensione:
Indirizzi per estratti:
Indirizzo: Gomez, M Univ Barcelona, Dept Quim Inorgan, Marti & Franques 1-11, E-08028Barcelona, Spain Univ Barcelona Marti & Franques 1-11 Barcelona Spain E-08028 ain
Citazione:
M. Gomez et al., "Palladium complexes containing bis(oxazolines): stoichiometric versus catalytic allylic alkylation", J CHEM S DA, (9), 2001, pp. 1432-1439

Abstract

The allylic palladium complexes (1L, for allyl=eta (3)-C3H5; 2L, for allyl=eta (3)-1,3-Ph2C3H3) with chiral 1,2-bis(oxazolinyl)benzene and 1,2-bis(oxazolinyl)ethane ligands L, (R,R)-A, (R,S)-A, (S,S)-B, (R,R)-C, and (S,S)-D,were synthesized and fully characterized, both in solution and in the solid state. Five crystal structures of palladium allyl complexes are described, three of them containing the non-substituted allyl group, (R,S)-1A, (S,S)-1B, and (S,S)-1D, and two containing the 1,3-diphenylallyl group, (R,S)-2Aand (S,S)-2B. A NMR study showed the existence of two isomers in solution for complexes containing 1,2-bis(oxazolinyl)benzene, endo and exo, with thediasteromeric excess of ca. 40% for type 1 complexes and ca. 75% for type 2 complexes. The catalytic behaviour of the palladium systems with the ligands described was tested for a model allylic alkylation reaction. The Pd/bis(oxazolinyl)benzene ((R,R)-A, (S,S)-B) catalytic systems showed low activity, but good asymmetric inductions, affording enantiomeric excesses up to 86%. However, the Pd/bis(oxazolinyl)ethane systems exhibited lower activity and worse enantioselectivity than for the analogous catalysts containing the rigid phenyl backbone. Stoichiometric reactions, modelling the nucleophilic attack step of the catalytic cycle, from palladium(II) (2L) complexes, led to lower enantiomeric excesses than under catalytic conditions.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 05/04/20 alle ore 03:37:13