3-(Thien-2-yl)- A nd 3-(thien-3-yl)allylamines, readily accessible from the corresponding thienyl aldehydes, can interact with a broad range of anhydrides and α,β-unsaturated acids chlorides (maleic, N itraconic-, and phenyl maleic anhydrides, N rotonyl and N innamyl chlorides, etc.) leading to the formation of a thieno[2,3-f[isoindole core. Usually, the reaction sequence involves three successive steps: Acylation of the nitrogen atom of the initial allylamine, the intramolecular Diels-Alder vinylarenÐµ (IMDAV) reaction, and the final aromatization of the dihydrothiophene ring in the Diels-Alder adducts. The scope and limitations of the proposed method were thoroughly investigated. It was revealed with the aid of X-ray analysis that the key step, the IMDAV reaction, proceeds through an exo-transition state, giving rise to the exclusive formation of a single diastereomer of the target heterocycle. In the case of maleic anhydrides, the method allows to obtain functionally substituted thieno[2,3-f[isoindole carboxylic acids, which are potentially useful substrates for further transformations and subsequent bioscreening. © 2020 Georg Thieme Verlag. All rights reserved.