The reactions of β‐azolylenamines 1 with sulfonyl azides 2 in acetonitrile furnished 1H‐4‐(azol‐5‐yl)‐1,2,3‐triazoles 3 in yields of 52–93 %. β‐Benzoylenaminones and β‐nitroenamine of type 1 also reacted with tosyl azide to form the same type of products 3, proving the generality and efficiency of the method for the synthesis of N‐unsubstituted 1,2,3‐triazoles. On the other hand, the reactions of 3‐(1‐aryl‐1,2,3‐triazol‐5‐yl)enamines with tosyl azide in the absence of a solvent afforded a mixture of (E)‐1‐dimethylamino‐2‐tosylaminoethenes 5 and N,N‐dimethyl‐N′‐tosylformamidine 6 in yields of 40–50 and 20 %, respectively. The formation of a variety of compounds from the reactions of enamines 1 with sulfonyl azides 2 is rationalized by the various possible transformations of the intermediate 5‐dimethylamino‐1,2,3‐triazolines 7.

The reactions of thioamides with azides in water were studied. It was reliably shown that the reaction of 2-cyanothioacetamides 1 with various types of azides 2 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 5 and 1,2,3-triazole-4-carbothioamides 4. This method can be extended to the one-pot reaction of sulfonyl chlorides and 6-chloropyrimidines 2′o with sodium azide, leading to final products in higher yields, that is, avoiding the isolation of unsafe sulfonyl azides. The method was furthermore applied to the reaction of N,N′-bis-(2-cyanothiocarbonyl)­pyrazine 1h with sulfonyl azides to afford bicyclic 1,2,3-thiadiazoles 8 and 1,2,3-triazoles 9 connected via a 1,1′-piperazinyl linker. 2-Cyanothioacetamides 1 were also shown to react with aromatic azides in water in the presence of alkali to afford 1-aryl-5-amino-1,2,3-triazole-4-carbothioamides 11. In contrast to aromatic azides and similarly to sulfonyl azides, 6-azidopyrimidine-2,4-diones 2o–q react with cyanothioacetamides to form N-pyrimidin-6-yl-5-dialkylamino-1,2,3-thiadiazole-4-N-l-carbimidamides 12. A mechanism was proposed to rationalize the role of water in changing the reactivity of azides toward 2-cyanothioacetamides.

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Reactions of β-azolyl enamines and nitrile oxides were studied by both experimental and theoretical methods. (E)-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 trans isomers during the reaction of (E)-β-imidazol-4-yl enamines with aryl and cyclohexylhydroxamoyl chlorides. Stepwise and concerted pathways for the reaction of β-azolyl enamines with hydroxamoyl chlorides were considered and studied at the B3LYP/Def2-TZVP level of theory combined with D3BJ dispersion correction. The reactions of benzonitrile oxide with both E- and Z-imidazolyl enamines have been shown to proceed stereoselectively to form trans- and cis-isoxazolines, respectively. The preference of E-isomers over Z-isomers, driven by the higher stability of the former, apparently controls the stereoselectivity of the investigated cycloaddition reaction with benzonitrilе oxide. Based on the reactivity of azolyl enamines towards hydroxamoyl chlorides, a novel, effective catalyst-free method was elaborated to prepare 4-azolyl-5-substituted isoxazoles that are otherwise difficult to obtain.

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