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Thienylallylamines, readily accessible from the corresponding thienyl aldehydes, react with maleic and trifluoromethylmaleic anhydrides leading to the formation of acids with a thieno[2,3- f ]isoindole core. The reaction sequence involves two successive steps: acylation of the nitrogen atom of the initial allylamine and the intramolecular Diels-Alder vinylarene (IMDAV) reaction. The scope and limitations of the proposed method were thoroughly investigated. It has been revealed with the aid of X-ray analysis and DFT calculations 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. The obtained functionally substituted thieno[2,3- f ]isoindole carboxylic acids are potentially useful substrates for further transformations and bioscreening. The antimicrobial evaluation of the obtained compounds revealed that 1-oxo-2-(3-(trifluoromethyl)phenyl)hexahydrobenzo[4,5]thieno[2,3- f ]isoindole-10-carboxylic acid is the most active sample in the synthesized library. It exhibits antibacterial activity against sensitive strains of Gram-positive bacteria, including S. aureus , Enterococcus faecium , Bacillus cereus , and Micrococcus luteus , as well as the Gram-negative bacteria E. coli and Pseudomonas fluorescens , with MIC values ranging from 4 to 64 μg mL -1 . 9-Oxo-8-phenyloctahydronaphtho[2,1- d ]thieno[2,3- f ]isoindole-10-carboxylic acid showed antifungal activity against yeast culture C. albicans with a MIC value of 32 μM.

In the title compound, C 22 H 19 NO 5 S·C 2 D 6 OS, the central six-membered ring has a slightly distorted boat conformation, while the fused pyrrolidine ring adopts an envelope conformation. These conformations are stabilized by O-H⋯O hydrogen bonds between the main compound and solvent mol-ecules. In addition, intra-molecular C-H⋯O hydrogen bonds in the main mol-ecule form two S (6) rings. Mol-ecules are connected by pairs of inter-molecular C-H⋯O hydrogen bonds, forming dimers with a R 2 2 (8) motif. These dimers form a three-dimensional network through O-H⋯O, O-H⋯S and C-H⋯O hydrogen bonds with each other directly and through solvent mol-ecules. In addition, weak π-π stacking inter-actions [centroid-to-centroid distances = 3.9937 (10) and 3.9936 (10) Å, slippages of 2.034 and 1.681 Å] are observed. The inter-molecular contacts were qu-anti-fied using Hirshfeld surface analysis and two-dimensional fingerprint plots, revealing the relative contributions of the contacts to the crystal packing to be H⋯H 41.7%, O⋯H/H⋯O 27.7%, C⋯H/H⋯C 17.0%, and S⋯H/H⋯S 7.5%., (© Mammadova et al. 2023.)