A simple and efficient approach has been developed for the synthesis of previously inaccessible 6-arylbenzo[c][1,7]naphthyridin-4(3H)-ones, which is based on the interaction of 3-amino-6-methyl-4-arylpyridin-2(1H)-ones and aromatic aldehydes in a strong acidic media (trifluoroacetic, phosphorous or polyphosphorous acids) under heating. The initial imine derivatives undergo Pictet–Spengler condensation to form intermediate 6-aryl-5,6-dihydrobenzo[c]-1,7-naphthyridin-4(3H)-ones, which are oxidized by atmospheric oxygen to give 3-amino-6-methyl-4-arylpyridin-2(1H)-ones as the final products.

In this work, we describe the development of the rearrangement for 7-aryl-substituted oxazolo [5,4-b]pyridines treated with aluminum chloride into synthetically hard-to-reach benzo [c][1,7]naphthyridinones. The discovered rearrangement is applied to a variety of electron-rich (hetero)arene substrates. It offers the advantages of mild conditions (90 °C temperature), fast reaction rates (<4 h), compatibility with air moisture, and the use of inexpensive commercial reagents. The proposed reaction mechanism and key elementary reaction acts were studied in detail using quantum chemical calculations. The photophysical properties of the synthesized compounds were studied by steady-state UV−vis spectroscopy.

A method has been developed for the preparation of oxazolo-[5,4-b]pyridin-2(1H)-ones based on the Hoffmann reaction of 2-oxo-1,2-dihydropyridine-3-carboxamides. Hydrolysis of oxazolo[5,4-b]pyridin-2(1H)-ones and the Hoffmann reaction of 2-oxo-1,2-dihydropyridine-3-carboxamides yielded 3-aminopyridin-2(1H)-ones, including 4-aryl substituted derivatives in the series, for which effective phosphors with a quantum yield of up to 0.78 were detected. Photophysical properties of 3-aminopyridin-2(1H)-ones were studied by UV and luminescence spectroscopy methods, and the relationship between their structure and photophysical properties was revealed.

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A new approach to the synthesis of fused benzothiophene derivatives was developed based on iodine-promoted photo-cyclization of 4,5-diarylsubstituted thiophenes obtained in three steps from commercially available compounds. Comparative analysis showed that photochemical cyclization is a more efficient method for the preparation of fused benzo[b]thiophene derivatives, compared to oxidative coupling 4,5-diarylsubstituted thiophenes in the presence of iron (III) chloride and palladium catalyzed intramolecular arylation. This approach provides an efficient synthesis of functionally substituted naphtho[2,1-b: 3,4-b ']dithiophenes, phenanthro[9,10-b] thiophenes, benzo[1,2-b: 3,4-b': 6 , 5-b '']trithiophenes, as well as new fused heterocycles containing a pyridine ring and / or a carbazole moiety