Asymmetric Diels-Alder Reaction Using a Montmorillonite-Entrapped Organocatalyst

Significance

Montmorillonite-supported (5S)-5-benzyl-2,2,3-trimethylimidazolidin-4-one was prepared and used for the asymmetric Diels-Alder reaction. Thus, the cation-exchange reaction of Na⁺-mont 1 with chiral imidazolidinone monohydrochloride 2 gave amine-montmorillonite catalyst 3 (amount of the amine supported on the solid was 7.4 wt %). Asymmetric Diels-Alder reaction of cyclohexadiene with acrolein was carried out in the presence of catalyst 3 to give the cycloaddition product in 82% yield with high enantioselectivity (endo = 92% ee, endo:exo = 94:6). Catalyst 3 was recovered and reused four times without any loss of catalytic activity (average 82% yield, 92% ee).