New hydrazones of 2-(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-ylthio)acetohydrazide have been obtained and the percentages of anti/syn -conformers were determined. Based on the analyses of 1 H NMR spectra, it was concluded that for hydrazones obtained from the 2-hydroxybenzaldehydes and 2'-hydroxycetophenones the ratio between the anti-and syn-conformers depends on the strength of intramolecular hydrogen bond (IMHB) between the nitrogen atom of the imino group and the proton of the 2-hydroxy group. It was shown that increase in IMHB strength results in stabilization of the anticonformer in solution.
New 4-cyclo(propyl-and butyl)pyridinium salts have been prepared by alkylation of 4-picolinium salt with α,ω-dibromoalkanes under phase-transfer catalysis conditions. The influence of the nature and the catalysis concentration was investigated. The experimentally determined H and C NMR chemical shifts were compared with the values calculated using the GIAO/DFT and HF approach in gas-phase and/or in methanol by using the IEF-PCM method.
Oxadiazole derivativesOxadiazole derivatives R 0290 S (2) -or N (3) -Substituted 2-Mercapto-5-(4-pyridyl)-1,3,4-oxadiazoles. -A series of substitution reactions at the mercapto group as well as the N(3) of the oxadiazole (I) is studied. Contrary to a former assumption, the condensation of the known hydrazide (XIII) with ethyl acetoacetate (XIV) doesn't lead to a ring closure, rather the linear hydrazone derivative (XV) is formed. Condensation reactions with ethyl isothiocyanate (XVI) or ethyl orthoformate (XVIII) show an analogous tendency. Starting from isonicotinic acid hydrazide (XX) the thiadiazole derivative (XXI) is obtained. The antitubercular activity of some of the synthesized compounds is screened. -(RUTAVICIUS, A.; KUODIS, Z.; Chem. Heterocycl. Compd. (N. Y.) 38 (2002) 7, 852-858; Inst. Chem., Akad., Vilnius 2600, Lithuania; Eng.) -H. Haber 15-136 2003 Oxadiazole derivatives
Durch Umsetzen der N‐Heterocyclen (I), (III), (V) und (VII) mit Orthoameisensäuretriethylester nach Methode A) werden die Amidoacetale (II), (IV), (VI) bzw. (VIII) erhalten.
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