Asymmetric Diels-Alder catalysis using a silica-grafted bis(oxazoline) catalyst: Influence of surface passivation on the enantioselectivity

ORGN 274

Dalit Rechavi1, Belen Albela2, Laurent Bonneviot2, and Marc Lemaire, marc.lemaire@univ-lyon1.fr1. (1) Laboratoire de Catalyse et Synthèse Organique, UMR 5622, Université Claude Bernard Lyon1, CPE Lyon, 43, bd du 11 novembre 1918, Villeurbanne, 69622, France, (2) Laboratoire de Chimie, UMR-CNRS 8152, Ecole Normale Superieure de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
Since 1997, several articles reporting the heterogenization of bis(oxazoline) ligands have appeared. We present here a heterogenization of a bis(oxazoline) ligand by covalent grafting onto an inorganic surface (silica). We tested the catalytic activity of the grafted catalyst in the Diels-Alder reaction, and obtained excellent enantioselectivities (up to 92% ee). The design of heterogeneous catalysts is still often performed by means of trial and error. On the way to a more rationally directed preparation of catalytic materials lies a better understanding of the factors which influence the catalytic outcome. As a step in this direction we have investigated the factors which influence the enantioselectivity in our system, and a quantitative correlation between the passivation of the silica and the enantioselectivity of the reaction is demonstrate.

 

Asymmetric Reactions and Syntheses
8:00 AM-12:00 PM, Monday, 14 March 2005 Convention Center -- Room 11A, Oral

Division of Organic Chemistry

The 229th ACS National Meeting, in San Diego, CA, March 13-17, 2005