Five-Membered Aromatic Heterocycles in Diels-Alder Cycloadditio Reactions: Theoretical Studies as a Complement of the Experimental Researches

The dienophilic behavior of electron-deficient substituted five-membered aromatic heterocyclices in polar cycloaddition reactions is studied from a theoretical point of view employing the global electrophilicity index to estimate the electrophilic character of the dienophiles and to compare them with the available experimental information. The type of substitution on the heteroatomic ring is also discussed. Complementary some new reactions of these substrates are described.