Enantioselective aza-Diels-Alder reaction of aldimines with "Danishefsky-type diene" catalyzed by chiral scandium(III)-N,N'-dioxide complexes.
J Org Chem
; 73(2): 630-7, 2008 Jan 18.
Article
em En
| MEDLINE
| ID: mdl-18088145
ABSTRACT
A new kind of complex prepared from scandium(III) triflate and l-proline-derived N,N'-dioxides has been developed to catalyze the enantioselective aza-Diels-Alder reaction between 1,3-butadiene (diene 1) and aldimines 2, affording the corresponding 2,5-disubstituted dihydropyridinones in moderate to high yields (up to 92%) with good enantioselectivities (up to 90% ee) at room temperature. A variety of aldimines including aromatic, heteroaromatic, conjugated, and aliphatic imines were found to be suitable substrates. Enantiopure samples (up to 99% ee) were obtained for some products by a single recrystallization. The absolute configuration of the products was determined by X-ray diffraction and CD analysis. On the basis of the investigation of 1H NMR spectra and the positive nonlinear effect, the catalyst structure was carefully discussed.
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Base de dados:
MEDLINE
Assunto principal:
Compostos Organometálicos
/
Piridonas
/
Escândio
/
Butadienos
/
Óxidos N-Cíclicos
/
Iminas
Idioma:
En
Ano de publicação:
2008
Tipo de documento:
Article