The thiophene nucleus as a diene or a dienophile in the intramolecular diels alder reaction of N-(2-thienyl)allene carboxamides

Abstract

N-(2-Thienyl)allene carboxamides undergo an Intramolecular Diels–Alder reaction, whereby, as a function of the substituents in the allenic ω-position, the thiophene nucleus acts as a diene (two H atoms or two methyl groups) or as a dienophile (two phenyl groups in the allenic ω-position).