Chiral catalysis using heterogeneous bis(oxazoline) ligands grafted onto silica

COLL 542

Dalit Rechavi, Laboratory of Catalysis and Organic Synthesis, UMR 5622, Université Claude Bernard Lyon1, C.P.E. Lyon, 3 rue Victor Grignard, 69616 Villeurbanne CEDEX, France and Marc Lemaire, Laboratoire de Catalyse et Synthèse Organique - UMR 5622, Université Claude Bernard Lyon 1, CPE Lyon, 43, bd du 11 novembre 1918, Villeurbanne, 69622, France.

Since 1997, several articles reporting the heterogenization of bis(oxazoline) ligands have appeared.1 We present here the first heterogenization of bis(oxazoline) ligands by covalent grafting onto an inorganic surface (silica).2

 

 

We tested the catalytic activity of the grafted catalyst in the Diels-Alder reaction, and obtained the best enantioselectivities so far among heterogeneous bis(oxazoline) catalysts (up to 92% ee).2

In cyclopropanation reactions, our system gives the best results reported so far for such reactions by silica-grafted bis(oxazolines) (up to 68% ee).

We have already shown the importance of protecting the silanol groups of the silica.2 We shall present our results considering the influence that the concentration of the ligand on the silica has on the enantioselectivity.

 

[1] Rechavi D., Lemaire M., Chem. Rev. 2002, 102, 3467.

[2] (a) Rechavi D., Lemaire M., Org. Lett. 2001, 3 (16), 2493. (b) Rechavi D., Lemaire M., J. Mol. Cat. A: Chemical 2002, 182 (1), 239.

 

 

Chiral Surfaces

Division of Colloid and Surface Chemistry
The 225th ACS National Meeting, New Orleans, LA, March 23-27, 2003