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Alkoxylation of N-substituted heterocyclic aminomethylsilyl moieties was studied using primary and tertiary alcohols. The reaction of 4-(silylmethyl)morpholine and 1-(silylmethyl)azepane under catalyst- and solvent-free conditions leads to the formation of dialkoxy- and trialkoxyaminomethylsilyl derivatives. The methanolysis of 4-(silylmethyl)morpholine resulted in trimethoxyaminomethylsilane formation as the main product and two byproducts, i.e., tetramethoxysilane and N-methylmorpholine.

3-Substituted 1,2,4-triazines easily react with nitronate anions to replace hydrogen atom in the position C-5 according to nucleophilic substitution mechanism and form appropriate oximes of 5-formyl- or 5-acyl-1,2,4-triazines. Present study has shown that the course of the reaction strongly depends on the structure of the substituent in the position C-3 of 1,2,4-triazine ring. Thus, 2-ethoxyphenyl substituent in 1,2,4-triazine allowed to form, besides appropriate oximes, also new nitronic acid derivatives stabilized by intramolecular hydrogen bonds. The synthesis pathway and molecular structures of oximes were confirmed by X-ray analysis performed for model compound 1-[3-(2-ethoxyphenyl)-1,2,4-triazin-5-yl]ethanone oxime. The presence of the new nitronic acid derivatives in the reaction mixture and the theoretical calculations at DFT/B3LYP/6-311++G(d,p) level strongly suggest that intermediate stabilized by bifurcated intramolecular hydrogen bond is a common intermediate for the construction of appropriate oximes.

The synthesis of 5-azido-3-methyl-1-phenyl-1H-pyrazolo[4,3-e][1,2,4]triazine 2 and 7-methyl-5-phenyl-1H-pyrazolo[4,3-e]tetrazolo[4,5-b][1,2,4]triazine 3 is described and the crystal and molecular structure of the latter is reported. This compound crystallizes in the monoclinic system, space group P21/n, with cell constants a = 11.607(2) A, b = 7.982(1) A, c = 13.147(2) A, β = 110.60(1)∘, Z = 4, T = 293 K and Dcal = 1.470 g cm−3. The structure was solved by direct methods and refined to R value of 0.0368 for 1906 reflections. The X-ray analysis revealed that the linear form of the tetrazolo-fused ring system of 3 exists in the crystal. The molecule as a whole has an almost planar conformation stabilized by the short intramolecular N⋅sH interaction. The molecular packing in the crystal is determined by the van der Waals forces only.

The reaction of 3-(methylthio)-5-propanoyl-1,2,4-triazine with p-chlorophenylhydrazine hydrochloride is completed within 5 min at room temperature in ethanol leading to p-chlorophenylhydrazone of 3-(methylthio)-5-propanoyl-1,2,4-triazine 1 in good yield. Title compound, 1 (R = C2H5, R1 = Cl, Z = SCH3), C13H14N5SCl, crystallizes in the monoclinic system, space group P21/n, with cell constants a = 12.5206(6) A, b = 9.3122(8) A, c = 12.8524(9) A, and β = 98.822(5)°, Z = 4, T = 293 K, Dcal = 1.381 g cm−3. The structure was solved by direct methods and refined to R value of 0.0671 for 1,679 reflections. The molecule as a whole has an almost planar conformation and possesses (E) configuration with respect to the C=N double bond. The crystal structure is stabilized by a weak N(13)–H(13)···N(2) intermolecular hydrogen bond and significant stacking, characteristic for π-electron systems.