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Titolo:
CATALYTIC ENANTIOSELECTIVE MICHAEL ADDITION-REACTIONS OF ALPHA-NITROESTERS TO ALPHA,BETA-UNSATURATED KETONES
Autore:
KELLER E; VELDMAN N; SPEK AL; FERINGA BL;
Indirizzi:
UNIV GRONINGEN,DEPT ORGAN & MOL INORGAN CHEM,NIJENBORGH 4 NL-9747 AG GRONINGEN NETHERLANDS UNIV GRONINGEN,DEPT ORGAN & MOL INORGAN CHEM NL-9747 AG GRONINGEN NETHERLANDS UNIV UTRECHT,DEPT CRYSTAL & STRUCT CHEM NL-3584 CH UTRECHT NETHERLANDS
Titolo Testata:
Tetrahedron : asymmetry
fascicolo: 20, volume: 8, anno: 1997,
pagine: 3403 - 3413
SICI:
0957-4166(1997)8:20<3403:CEMAOA>2.0.ZU;2-U
Fonte:
ISI
Lingua:
ENG
Soggetto:
ASYMMETRIC NITROALDOL REACTION; CONJUGATE ADDITION; BINOL COMPLEX;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
26
Recensione:
Indirizzi per estratti:
Citazione:
E. Keller et al., "CATALYTIC ENANTIOSELECTIVE MICHAEL ADDITION-REACTIONS OF ALPHA-NITROESTERS TO ALPHA,BETA-UNSATURATED KETONES", Tetrahedron : asymmetry, 8(20), 1997, pp. 3403-3413

Abstract

Enantioselective Michael additions of alpha-nitroesters 2a-d with alpha,beta-unsaturated ketones were carried out in the presence of a catalytic amount of chiral Al-Li-(R,R')-2,2'-dihydroxy-1,1'-binaphthyl ('AlLiBINOL') complex prepared in situ from LiAlH4 and 2.45 equiv. of (R,R')-BINOL. The enantioselectivity of the Michael addition proved to beextremely temperature dependent: Michael adduct 4a showed 7% e.e. when the reaction was performed at RT, whereas 72% e.e. of the opposite enantiomer of 40 was found when the 1,4-addition was performed at -23 degrees C. Solvent variation showed that tetrahydrofuran gave the highest selectivity (up to 80% e.e.), whereas the highest enantioselectivity for the opposite enantiomer was found in methylene chloride (up to 25%). X-Ray structure analysis of the AlLi3BINOL3 complex 6 in combination with Al-27 NMR studies showed that 'AlLiBINOL' is a mixture of aluminium complexes in solution. (C) 1997 Elsevier Science Ltd.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/11/20 alle ore 04:08:26