Synthesis
5.1.1 Synthesis of 5-(2-chlorophenyl)-1,3,4-thiadiazol-2-amine (68): 2-chlorobenzoic acid (5.18 g, 25 mmol) and aminothiourea (2.28 g, 25 mmol) were dissolved in POCl3 (7 ml) and stirred vigorously for 0.5 hr at 75 °C. After completion of the reaction, H2O (30 ml) was added and the mixture was heated to reflux for 4 hours. Subsequently, the reaction mixture was adjusted with 50% NaOH solution to pH 8. The precipitate was collected by filtration and the filter cake was purified by recrystallization from ethanol to give the yellow crystalline product 68 in a yield of 3.90 g, 88% yield, melting point 190-192 °C (EtOH). The product was analyzed by ESI-MS, m/z: 212.1 [M + H]+; 1H NMR (CDCl3) δ 7.45-7.50 (m, 4H), 7.60-7.62 (m, 1H), 7.99-8.01 (m, 1H). Compounds 60-81 were synthesized in the same way.
References
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[4] Medicinal Chemistry Research, 2012, vol. 21, # 6, p. 816 - 824
[5] Journal of Chemical Research, 2014, vol. 38, # 6, p. 347 - 350
