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The C–H functionalization strategy was first applied to the Cu-mediated radical arylation reactions of triazolotriazines with aromatic diazonium salts. A series of C(3)-modified triazolo[5,1- c ][1,2,4]triazines were obtained in yields of up to 80% under mild conditions. The radical nature of the reaction mechanism was established by the TEMPO radical trap experiments. The developed method is characterized by its versatile application opportunities, particularly it allows C(3)-arylated azoloazine-derived compounds of various architectures to be available. The elaborated synthetic strategy is of interest in the directed design of azaheterocyclic biomolecules with diverse pharmacological applications. [ABSTRACT FROM AUTHOR]

A synthetic approach to prepare boron-enriched π-conjugated photoactive molecular systems based on ortho-carborane using the Cu(I)-catalyzed Sonogashira-type coupling reaction has been developed. The obtained luminophores have been found to possess absorption in the range of 300 to 400 nm, emission of up to 700 nm, and photoluminescence quantum yields of up to 99% in non-polar solvents. TD-DFT calculations have demonstrated that the luminophores are characterized by phosphorescent emission behavior with a lifetime of about 7 μs. In addition, the rigidochromism for the synthesized compounds has been revealed; particularly, the transition electronic state and bathochromic shift have been elucidated in the emission spectra. The exhibited luminescent characteristics indicate that the elaborated vinylcarborane fluorophores could be considered as promising building blocks in the design of advanced photofunctional materials for molecular electronics. [ABSTRACT FROM AUTHOR]

A series of 2,4-disubstituted pyrrolo[2,1-f][1,2,4]triazines containing both aryl and thienyl substituents were synthesized by exploiting the 1,3-cycloaddition reaction of N(1)-ethyl-1,2,4-triazinium tetrafluoroborates with dimethyl acetylenedicarboxylate. The antiviral activity of the synthesized compounds against influenza virus strain A/Puerto Rico/8/34 (H1N1) was studied in experiments on Madin-Darby canine kidney (MDCK) cell culture. Among the pyrrolo[2,1-f][1,2,4]triazine derivatives, compounds with low toxicity and high antiviral activity were identified. Dimethyl 4-(4-methoxyphenyl)-7-methyl-2-p-tolylpyrrolo[2,1-f][1,2,4]triazine-5,6-dicarboxylate was found to demonstrate the best antiviral activity (IC50 4 µg/mL and selectivity index 188). Based on the results of in vitro tests and molecular docking studies performed, a plausible mechanism of action for these compounds was suggested to involve inhibition of neuraminidase. [ABSTRACT FROM AUTHOR]

A synthetic strategy based on reactions of cyclic imine oxides, namely 2H-imidazole 1-oxides, with thiophenols mediated by acetyl chloride was successfully applied as a convenient tool to obtain a series of novel azaheterocyclic molecules, including water-soluble hydrochloride forms. Optimized reaction conditions found herein for the nucleophilic substitution of hydrogen (SNH) in non-aromatic azaheterocyclic substrates via the "addition-elimination" (SNH AE) scheme enabled 15 arylthiolated 2H-imidazoles to be prepared in yields of up to 90%. The developed methodology discloses an original synthetic way to obtain numerous azaheterocyclic molecules, which are of interest in the field of medicinal chemistry and materials science. [ABSTRACT FROM AUTHOR]

The strategy of the nucleophilic substitution of hydrogen (SNH) was first applied for the metal-free C-H/C-H coupling reactions of 4H-imidazole 3-oxides with indoles. As a result, a series of novel bifunctional azaheterocyclic derivatives were obtained in yields up to 95%. In silico experiments on the molecular docking were performed to evaluate the binding possibility of the synthesized small azaheterocyclic molecules to the selected biotargets (BACE1, BChE, CK1δ, AChE) associated with the pathogenesis of neurodegenerative diseases. To assess the cytotoxicity for the synthesized compounds, a series of in vitro experiments were also carried out on healthy human embryo kidney cells (HEK-293). The leading compound bearing both 5-phenyl-4H-imidazole and 1-methyl-1H-indole moieties was defined as the prospective molecule possessing the lowest cytotoxicity (IC50 > 300 µM on HEK-293) and the highest binding energy in the protein–ligand complex (AChE, −13.57 kcal/mol). The developed compounds could be of particular interest in medicinal chemistry, particularly in the targeted design of small-molecule candidates for the treatment of neurodegenerative disorders. [ABSTRACT FROM AUTHOR]

Calix[4]arenes are, probably, the mostly explored macrocycles in the supramolecular chemistry. By means of the synthetic modification/functionalization of the upper or lower rims, as well as meso‐positions, the "host‐guest" properties of these macrocycles can be modulated in order to accommodate the guest molecules of various sizes and nature for supramolecular and coordination chemistry, and to perform various functions for materials science and for biomedical applications. In this review, we wish to highlight the most prospective synthetic approaches for the direct C−H functionalization of calixarene core with various functional moieties. Depending on the nature of the functional moiety these calix[4]arenes can serve as drug carriers and nano‐containers for the recognition, encapsulation or storage of bioactive molecules and for many other applications. Current review article deals with the recent examples of C(H)‐functionalization of calix[4]arenes, as well as selected patterns of direct C(H)‐modification of some calix[6]arenes and calix[4]pyrroles. [ABSTRACT FROM AUTHOR]

Mono- and bis-2-thienyl-substituted 1,3,7-triazapyrenes have been synthesized for the first time via BF3-mediated C–H/C–Li coupling of 1,3,7-triazapyrene with 2-thienyllithium in 33 and 51% yields, respectively. The photophysical properties of these polycyclic azaaromatics have been studied, with emission in the range of 450–500 nm and fluorescence quantum yields of up to 99% in methanol solutions being revealed. The turn-off chemosensing properties of 2-thienyl-substituted 1,3,7-triazapyrenes for the selective detection of nitroaromatics have also been assessed; in particular, the quenching constants according to the Stern–Volmer model, the quenching sphere radius according to the Perrin model, the detection limit and the quenching efficiency have been determined. In particular, 6,8-bis-(thiopen-2-yl)-1,3,7-triazapyrene, characterized by 10 times the quenching constant and limit of detection (LOD) compared to the mono-substituted analog, can be considered as the most promising chemosensor for determining nitroaromatic compounds. DFT calculations confirm the presence of intramolecular charge transfer (ICT) effects in the case of the obtained fluorophores and clarify the quenching mechanism for nitroaromatics. [ABSTRACT FROM AUTHOR]

A convenient method for the synthesis of new highly in non-polar solvents soluble photoactive pentafluorophenyl-substituted and extended alkoxyphenyl-substituted 2,2′-bipyridines is reported. The synthetic strategy for the preparation of such ligands involves a sequence of several structural transformations, such as O-alkylation, nucleophilic substitution of hydrogen (SNH) in 1,2,4-triazine precursors via the 'addition–elimination' scheme, and the subsequent conversion of the obtained 1,2,4-triazines into 2,2′-bipyridines by means of the aza-Diels–Alder reaction. The photophysical properties of the synthesized novel pentafluoroaryl-substituted 2,2′-bipyridines were comprehensively studied. The obtained photophysical data indicate the competitive advantages of the herein reported pentafluoroarylated push–pull fluorophores, bearing extended aliphatic moieties, over their analogues containing benzoxy or phenolic fragments in terms of improvement in quantum yield and well-pronounced positive solvatochromism confirmed by the mathematical analysis according to the Lippert–Mataga equation. [ABSTRACT FROM AUTHOR]