were dried under Na2SO4 and evaporated to give 4a, 0.28 g (67%), mp 178-180 °C (from 2- propanol).
3-[(6-Methyl-2-morpholinopyrimidin-4-ylthio)methyl]-5-methylthio-4-phenyl-1,2,4-triazole (4b) was synthesized as 4a. Method A. Yield 88 %, mp 189-190°C (from ethanol-water 5/1). Method B. yield 81%, mp 190-192°C; 1H NMR (DMSO-d6), d, ppm: 2.18 (s, 3H, CH3), 3.61 (m, 8H, morpholine), 4.51 (s, 2H, SCH2), 6.43 (s, 1H, CH-pyrimidine), 7.43-7.46, 7.53-7.55 (2m, 5H, phenyl); 13C NMR (DMSO-d6), d, ppm: 15.0, 22.3, 24.2, 66.7, 107.0, 127.9, 130.5, 130.7, 133.2, 152.7, 153.2, 160.6, 166.6, 166.9. IR, ., cm-1: 2957, 2847 (CH), 1596, 1550, 1499 (C=C, C=N), 1440 (CH3), 1293 (S-CH2), 1120 (C-O-C). Anal. Calcd. for C19H22N6OS2: C, 55.05; H, 5.35; N, 20.27. Found: C, 54.95; H, 5.18; N, 20.39.
2-Cyclohexylamino-5-[(6-methyl-2-morpholinopyrimidin-4-ylthio)methyl]-1,3,4-oxadiazole (5a). Method A. Iodine in a 5% solution of potassium iodide in ethanol was added dropwise to a cooled (5-7 °C) mixture of hydrazinecarbothioamide 2a (0.42 g, 1 mmol), ethanol (7 ml) and 2 N sodium hydroxide solution (0.7 ml) under stirring till the color of iodine persisted. The reaction mixture was allowed to warm to room temperature and then was heated at 45-50°C for 2 hours. The solvent was removed in vacuum, the residue was poured over crushed ice and neutralized with acetic acid. The solid formed was filtered of, washed with water, dried and crystallized from benzene to give 0.22 g (57%) of 5a, mp 159-160 °C; 1H NMR (DMSO-d6), d, ppm: 1.14-1.29, 1.51-1.58, 1.63-1.73, 1.82-1.91 (4m, 10H, cyclohexyl), 2.21 (s, 3H, CH3), 3.20-3.29 (m, 1H, cyclohexyl), 3.61-3.64, 3.69-3.72 (2m, 8H, morpholine), 4.47 (s, 2H, SCH2), 6.57 (s, 1H, CH- pyrimidine), 7.51 (d, J = 9 Hz, 1H, NH); 13C NMR (DMSO-d6), d, ppm: 22.7, 24.3, 25.1, 32.9, 44.5, 52.4, 66.7, 107.0, 157.0, 160.9, 163.6, 166.8, 167.1; IR, ., cm-1: 3332, 3250 (NH), 2931, 2853 (CH), 1578, 1552, 1509 (C=C, C=N), 1447 (CH3), 1294 (S-CH2), 1225, 1023 (C-O-C oxadiazole), 1119 (C-O-C). Anal. Calcd. for C18H26N6O2S: C, 55.36; H, 6.71; N, 21.52. Found: C, 55.32; H, 6.80; N, 21.67.
Method B. A mixture of hydrazinecarbothioamide 2a (0.42 g, 1 mmol) and mercury (II) acetate (0.32 g, 1 mmol) in ethanol (15 ml) was heated at reflux for 30 min. and filtered off. The solvent was evaporated in vacuum, the solid was crystallized from benzene to give 0.34 g (87%) of 5a, mp 159-160 °C.
5-[(6-Methyl-2-morpholinopyrimidin-4-ylthio)methyl]-2-phenylamino-1,3,4-oxadiazole (5b). This was synthesized in a similar manner to 5a using Method B. Yield 89%, mp 178-180 °C (from tetrahydrofuran); 1H NMR (DMSO-d6), d, ppm: 2.22 (s, 3H, CH3), 3.60-3.62, 3.70-3.72 (m, 8H, morpholine), 4.60 (s, 2H, SCH2), 6.60 (s, 1H, CH-pyrimidine), 7.00 (t J = 8 Hz, 1H, phenyl), 7.33 (t J = 8 Hz, 2H, phenyl), 7.52 (d J = 8 Hz, 2H, phenyl), 10.47 (s, 1H, NH); 13C NMR (DMSO-d6), d, ppm: 22.6, 24.3, 44.5, 66.7, 107.0, 117.6, 122.5, 129.8, 139.3, 157.9, 160.6, 160.9, 166.9, 167.0; IR, ., cm-1: 3260 (NH), 2918, 2852 (CH), 1603, 1552, 1500 (C=C, C=N), 1449 (CH3), 1294 (S-CH2), 1225, 1015 (C-O-C oxadiazole), 1119 (C-O-C). Anal. Calcd. for C18H20N6O2S: C, 56.23; H, 5.24; N, 21.86. Found: C, 56.35; H, 5.28; N, 21.75.
2-Cyclohexylamino-5-[(6-methyl-2-morpholinopyrimidin-4-ylthio)methyl]-1,3,4-thiadiazole (6a). Hydrazinecarbothioamide 2a (0.42 g, 1 mmol) was added in portion to conc. sulfuric acid
