New ruthenium catalysts containing chiral Schiff bases for the asymmetric hydrogenation of acetophenone

Graphic A series of new chiral N 4-Schiff bases, containing amine or sulfonamide functionalities has been synthesized. Coupled with ruthenium catalysts, these Schiff bases induce interesting results in the hydrogenation of acetophenone: complete conversion and 76% ee were obtained with the catalytic...

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Bibliographic Details
Published in:Tetrahedron: asymmetry 2004-05, Vol.15 (10), p.1569-1581
Main Authors: Karamé, Iyad, Jahjah, Mohamed, Messaoudi, Abdelhalim, Tommasino, M.Lorraine, Lemaire, Marc
Format: Article
Language:English
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Summary:Graphic A series of new chiral N 4-Schiff bases, containing amine or sulfonamide functionalities has been synthesized. Coupled with ruthenium catalysts, these Schiff bases induce interesting results in the hydrogenation of acetophenone: complete conversion and 76% ee were obtained with the catalytic system Ru(PPh 3) 3Cl 2/(1 R,2 R)- N, N′-bis-(2- p-tosylaminobenzylidene)-1,2-diphenylethylenediamine. A very important phosphine co-ligand effect was observed on both activity and enantioselectivity of the catalysts. However, without the co-ligand, we obtained an enantioselectivity for the ( R)-enantiomer, whereas with nonchiral co-ligand an enantioselectivity for the ( S)-enantiomer was observed.
ISSN:0957-4166
1362-511X
DOI:10.1016/j.tetasy.2004.03.023