Effect of Lewis Acid Catalysis on the Diels-Alder Reaction between Methyl (Z)-(S)-4,5-(2,2-Propylidenedioxy)pent-2-enoate and Cyclopentadiene. A Theoretical Study.

The Diels-Alder reactions of methyl (Z)-(S)-4,5-(2,2-propylidenedioxy)pent-2-enoate and (Z)-(S)-4,5-(2,2-propylidenedioxy)pent-2-enoic acid with cyclopentadiene catalyzed by AlCl(3) have been theoretically studied at the B-LYP/6-31G level. The results obtained show that the catalyst increases both the endo/exo and syn/anti selectivity, in good qualitative agreement with the experimental observations. The origin of the selectivity and the role of the catalyst are discussed.