EFFECT OF CLAY CALCINATION ON CLAY-CATALYZED DIELS-ALDER REACTIONS OF CYCLOPENTADIENE WITH METHYL AND (-)-MENTHYL ACRYLATES

Zn(II) and Fe(III)-exchanged K10-montmorillonites, activated by several methods, are used as catalysts in the reaction between methyl acrylate and cyclopentadiene. Calcined clays are better catalysts than dried clays. Zn(II) clays, dried and calcined, are compared as catalysts of the asymmetric Diels-Alder reaction between (-)-menthyl acrylate and cyclopentadiene. Calcined clay again shows a higher catalytic activity and leads to better percentages of diastereomeric excess. Furthermore, calcined clays are easily recovered with no loss of catalytic properties.