Abstract
K10 montmorillonites exchanged with different cations, dried at 120°C or calcined at 550°C, are used as catalysts in Diels-Alder reactions of methyl and (-)-menthyl acrylates with cyclopentadiene. In general, calcined clays give rise to better conversions and selectivities. Zr(IV) and specially Ti(IV) clays display the best catalytic activities. However, the best asymmetric induction is achieved with Cr(III) and Ca(II) calcined clays. Clays containing easily reducible cations behave differently due to the cyclopentadiene polymerization via radical cations.