Attempted use of 3-arylglutaconic acids in the three-component version of the Castagnoli–Cushman reaction with amines and aromatic aldehydes resulted in an unexpected formation of 4,6-diaryl 1,6-dihydropyridine-2­(3H)-ones. These are of interest as representatives of a rare heterocyclic chemotype for de novo biological investigation. Alternatively, these compounds can be oxidized into their 2-pyridone counterparts, stereoselectively reduced to give cis-configured 4,6-diaryl 2-piperidones, or isomerized to 5,6-dihydropyridin-2­(1H)-ones. All the three scaffolds are well represented in the bioactive compound domain.

The earlier reported three-component Castagnoli–Cushman-type synthesis of 1,4,6-trisubstituted 1,6-dihydropyridin-2-(3H)-ones from 3-arylglutaconic acids, primary amines, and aromatic aldehydes has been further investigated. It was shown to proceed via 3-arylglutaconic anhydrides, which, in turn, were found to give superior results in the two-component reactions with imines. The initial formation of the Castagnoli–Cushman carboxylic acids was shown to be the case, and their decarboxylation was found to follow a complex, “forked” pathway, which was confirmed by deuterium incorporation experiments.

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Novel 1,2-bis(2-alkylthien-3-yi)hexafluorocyclopentenes containing the alkylthio or alkylsulfonyl groups in positions 5 and 5' of the thiophene rings were synthesized. These compounds are photoehromes; their photochromic properties were studied.

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