4-oxadiazole

The synthesis of new hybrids 1,3,4-oxadiazol-2-thione with acridine 9(10H)-one is carried out. Their structure is confirmed by LC-MS, IR-, 1H and 13C NMR-spectroscopy. The thione-thiol equilibrium was investigated in eight solvents with different relative permittivity with the help of UV-spectroscopy and quantum chemistry methods using DFT/B3LYP and HF bases. The results of the experimental calculations are in agreement with theoretical ones and have shown the prevalence of the thione.

Following the N-alkylation reaction of starting 2-chloro-N-(5-aryl-1,3,4-oxadiazol-2-yl)-acetamides 1a-c with 2,4-thiazolidinedione or 5-sudstituted isatins the corresponding non-condensed oxadiazole derivatives with thiazolidine 2a-c or isatin 4a-h fragments were synthesized. The obtained compounds have been used in Knoevenagel condensation with 5R-isatin (for 2a-c) or 4-thiazolidinone derivatives (for 4a-h) for synthesis of the appropriate 5-ylidenederivatives 3a-g, 5a-k and 6a-d.