AlPO4-catalyzed Diels-Alder reaction of cyclopentadiene with (-)-menthyl acrylate. Influence of catalyst surface properties

Different synthetic AlPO4 systems are effective yet mild acid catalysts for the heterogeneous cycloaddition reaction of cyclepentadiene with (-)-menthyl acrylate. The reaction proceeds selectively under mild conditions and in a relatively short reaction time with an almost total conversion, a high endo/exo ratio, and a reasonable asymmetric induction. When the reactions are carried out without solvent, some correlations are obtained between the number of acid sites, titrated with pyridine, and reaction yields, endo/exo and diastereofacial selectivities. The positive influence of surface area of catalysts is also determined. However, the lack of good correlations between reaction results and surface properties of the catalysts indicates the influence of some other factors.