A DFT Study of the Regioselectivity in Intramolecular Diels-Alder Reactions with Formation of a Tricyclodecane Skeleton

Three different intramolecular Diels-Alder (IMDA) reactions associated with the formation of fused and bridged tricyclodecane skeletons have been studied at the B3LYP/6-31G(d) computational level. While substitution on the diene and dienophile fragments modulates the polar character of the reaction, the strain effect produced by the methylene tether affects the activation energy, and its torsion controls the different regioisomeric channels of the IMDA process. Analysis of the reactivity indices recently proposed [J. Soto-Delgado et al., Org. Biomol. Chem., 2010, 8, 3678] within the conceptual density functional theory allows for the characterization of the mechanism including the charge transfer within the reagents involved in these IMDA reactions as well as for the direction of the electronic flux in the intramolecular processes.