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Titolo:
COPPER-CATALYZED CONJUGATE ADDITIONS OF ORGANOZIRCONOCENES - SYNTHETIC AND MECHANISTIC STUDIES
Autore:
WIPF P; XU WJ; SMITROVICH JH; LEHMANN R; VENANZI LM;
Indirizzi:
UNIV PITTSBURGH,DEPT CHEM PITTSBURGH PA 15260 ETH ZENTRUM,INORGAN CHEM LAB CH-8092 ZURICH SWITZERLAND
Titolo Testata:
Tetrahedron
fascicolo: 7, volume: 50, anno: 1994,
pagine: 1935 - 1954
SICI:
0040-4020(1994)50:7<1935:CCAOO->2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
TRANSITION-METAL CATALYSIS; CARBON BOND FORMATION; CP2ZR(H)CL SCHWARTZ REAGENT; ONE-POT CONVERSION; HYDROZIRCONATION-TRANSMETALATION; ORGANIC-SYNTHESIS; ALKENYLZIRCONIUM DERIVATIVES; ORGANOCOPPER REAGENTS; HYDRIDO COMPLEXES; GRIGNARD-REAGENTS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
84
Recensione:
Indirizzi per estratti:
Citazione:
P. Wipf et al., "COPPER-CATALYZED CONJUGATE ADDITIONS OF ORGANOZIRCONOCENES - SYNTHETIC AND MECHANISTIC STUDIES", Tetrahedron, 50(7), 1994, pp. 1935-1954

Abstract

In the presence of 3-10 mol % of Cu(l) salts such as CuBr.SMe(2) or CuCN, alkylzirconocenes add readily to alpha,beta-unsaturated ketones, aldehydes, and sulfones. The reaction yield is sensitive to the presence of Lewis acids and bases. Steric hindrance as well as a broad rangeof functional groups are tolerated in the conjugate addition process. Unsaturated N-acyl oxazolidinones give high diastereoselectivities for the formation of the new asymmetric carbon. The resulting zirconium enolates can be used for tandem aldol addition reactions to aldehydes. Depending on the type of copper salt used, slow, or fast formation ofcopper mirror occurs, but no intermediate copper species is detected spectroscopically. Therefore, a mechanism involving enone complexationby the Lewis-acidic zirconocene followed by inner-sphere transfer of the alkyl substituent to chelated Cu(l) is proposed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 09/08/20 alle ore 23:19:46