Isoxazolyl-Derived 1,4-Dihydroazolo[5,1-][1,2,4]Triazines: Synthesis and Photochemical Properties.

New fluorescent dyes containing an assembled 1,4-dihydroazolo[5,1-][1,2,4]triazine (DAT) core and an isoxazole ring were synthesized through a reaction between diazopyrazole or diazoimidazoles and isoxazolyl-derived enamines in mild conditions. The photophysical characteristics (maxima absorption and emission, Stokes shifts, fluorescent quantum yields, and fluorescence lifetimes) of the new fluorophores were obtained. The prepared DATs demonstrated emission maxima ranging within 433-487 nm, quantum yields within 6.

Selective Synthesis of Azoloyl -1,2,3-Triazoles and Azolyl Diazoketones: Experimental and Computational Insights.

Here, we report that the reaction of enaminones, from a class of azole series, with sulfonyl azides leads to a difficult-to-separate mixture of two pairs of compounds: (1) 4-azoloyl--1,2,3-triazoles with sulfonamides and (2) azolyl diazoketones with -sulfonamidines, as a result of the implementation of two competing reactions. On one hand, the electron-donating methyl or methoxy group in the aryl para-position of arylsulfonyl azides favors the production of -1,2,3-triazoles together with sulfonamides. On the other hand, the use of highly electrophilic 4-nitrophenylsulfonyl azide promotes the formation of diazoketones and sulfonamidines.

Water/Alkali-Catalyzed Reactions of Azides with 2-Cyanothioacetamides. Eco-Friendly Synthesis of Monocyclic and Bicyclic 1,2,3-Thiadiazole-4-carbimidamides and 5-Amino-1,2,3-triazole-4-carbothioamides.

The reactions of thioamides with azides in water were studied. It was reliably shown that the reaction of 2-cyanothioacetamides with various types of azides in water in the presence of alkali presents an efficient, general, one-step, atom-economic, and eco-friendly method for the synthesis of 1,2,3-thiadiazol-4-carbimidamides and 1,2,3-triazole-4-carbothioamides . This method can be extended to the one-pot reaction of sulfonyl chlorides and 6-chloropyrimidines with sodium azide, leading to final products in higher yields, that is, avoiding the isolation of unsafe sulfonyl azides.

Combined experimental and theoretical studies of regio- and stereoselectivity in reactions of β-isoxazolyl- and β-imidazolyl enamines with nitrile oxides.

Reactions of β-azolyl enamines and nitrile oxides were studied by both experimental and theoretical methods. ()-β-(4-Nitroimidazol-5-yl), (5-nitroimidazol-4-yl) and isoxazol-5-yl enamines smoothly react regioselectively at room temperature in dioxane solution with aryl, pyridyl, and cyclohexylhydroxamoyl chlorides without a catalyst or a base to form 4-azolylisoxazoles as the only products in good yields. The intermediate 4,5-dihydroisoxazolines were isolated as isomers during the reaction of ()-β-imidazol-4-yl enamines with aryl and cyclohexylhydroxamoyl chlorides.

[A new setup for the generation and studies of mono-disperse microbiological aerosols in medical-and-biological research].

A setup for the generation and studies of mono-disperse microbiological aerosols is described in the paper. Coefficients of 3 microm aerosol deposition in the respiratory tract of mice and rats were refined by using the above setup. The probability of deposition of such particles in the trachea and lungs of mice was proven to be equal to 1.