The reaction of dimethylacetylenedicarboxylate with 1-methyl-2-vinylpyrrole is temperature dependent. At 80° the predominant reaction is the [4π + 2π] cycloaddition to give dimethyl 1-methyl-6,7-dihydroindole-4, 5-dicarboxylate, whereas at room temperature Michael addition of the acetylenic ester at the 5-position of the pyrrole ring to give fumaric and maleic ester derivatives also occurs. Unequivocal
Various heteroarenes, such as indole, carbazole, dibenzofuran, dibenzothiophene, etc., were easily constructed by the Diels-Alderreaction of the corresponding vinyl-substituted pyrrole, indole, be...