H. P. Lakum, D. R. Shah, and K. H Chikalia
Vol 000
piperazine); MS (m/z): 551.7 [M+]. Anal. Calcd. for
C30H30N8OS: C, 65.43; H, 5.49; N, 20.35. Found: C, 65.25; H,
5.47; N, 20.31.
155.77 (oxadiazole C–N piperazine), 153.59 (Ar–C), 143.24
(Ar–C–NO2), 140.15, 137.19, 136.29, 134.17, 133.07, 131.21,
129.47, 128.42, 124.43, 121.16, 120.06, 119.34, 118.21 (15 Ar-
C), 47.13, 46.37, 45.77, 44.81 (8C of piperazine); MS (m/z):
596.6 [M+]. Anal. Calcd. for C30H29N9O3S: C, 60.49; H, 4.91;
N, 21.16. Found: C, 60.41; H, 4.90; N, 21.11.
2-(4-(4-(4-Phenylpiperazin-1-yl)quinazolin-2-yl)piperazin-1-
yl)-5-(o-tolylthio)-1,3,4-oxadiazole (9b).
Yield: 75%; mp
226–230 °C; IR (KBr) cmÀ1: 2943 (aromatic C–H), 1637 (C=N
oxadiazole ring), 1173 (oxadiazole C–O–C); 1H NMR
(400 MHz, DMSO) δ 7.92–7.71 (m, 4H), 7.62–6.83 (m, 5H,
Ar–H), 6.70–6.61 (m, 4H, Ar–H), 3.84–3.59 (m, 8H,
piperazine), 3.52–3.33 (m, 8H, piperazine), 2.63 (s, 3H, Ar–
CH3); 13C NMR (100 MHz, DMSO) δ 178.29 (oxadiazole C–S–
Ar), 169.37 (quinazoline ring N=C–N C2 position), 165.18
(quinazoline C4 position), 156.73 (quinazoline ring C=C–N),
155.52 (oxadiazole C–N piperazine), 153.75 (Ar–C), 140.36,
136.49, 134.30, 132.27, 130.17, 129.61, 128.26, 127.43,
126.39, 125.04, 124.44, 123.25, 122.27, 121.45 (16 Ar–C),
49.39, 48.21, 47.05, 46.33 (8C of piperazine), 24.21 (Ar–CH3);
MS (m/z): 565.3 [M+]. Anal. Calcd. for C31H32N8OS: C, 65.93;
H, 5.71; N, 19.84. Found: C, 66.05; H, 5.69; N, 19.79.
2-((2-Methoxyphenyl)thio)-5-(4-(4-(4-phenylpiperazin-1-yl)
quinazolin-2-yl)piperazin-1-yl)-1,3,4-oxadiazole (9f). Yield: 64%;
mp 166–169 °C; IR (KBr) cmÀ1: 2969 (aromatic C-H), 1659 (C=N
1
oxadiazole ring), 1561 (N–O of nitro), 1175 (O–C ether); H NMR
(400 MHz, DMSO) δ 8.08–7.83 (m, 4H, Ar–H), 7.81–7.62 (m, 5H,
Ar–H), 7.54–6.95 (m, 4H, Ar–H), 4.15 (s, 3H, Ar–OCH3), 3.67–
3.52 (m, 8H, piperazine), 3.47–3.32 (m, 8H, piperazine); 13C NMR
(100 MHz, DMSO)
δ 173.23 (oxadiazole C–S–Ar), 165.22
(quinazoline ring N=C–N C2 position), 161.74 (quinazoline C4
position), 153.67 (quinazoline ring C=C–N), 151.13 (oxadiazole C–
N piperazine), 150.16 (Ar–C), 139.64, 137.17, 135.46, 133.27,
130.19, 129.77, 127.51, 125.47, 124.72, 123.20, 121.15, 120.48,
119.61, 118.40 (16 Ar–C), 60.14 (Ar–OCH3), 48.13, 47.42, 46.54,
45.27 (8C of piperazine); MS (m/z): 581.5 [M+]. Anal. Calcd. for
C31H32N8O2S: C, 64.12; H, 5.55; N, 19.30. Found: C, 64.26; H,
5.54; N, 19.36.
2-(4-(4-(4-Phenylpiperazin-1-yl)quinazolin-2-yl)piperazin-1-
yl)-5-(p-tolylthio)-1,3,4-oxadiazole (9c).
Yield: 79%; mp
289–294 °C; IR (KBr) cmÀ1: 2986 (aromatic C-H), 1653
(C=N oxadiazole ring), 1167 (oxadiazole C–O–C); 1H NMR
(400 MHz, DMSO) δ 7.83–7.67 (m, 4H, Ar–H), 7.58–6.76
(m, 5H, Ar–H), 6.71–6.53 (m, 4H, Ar–H), 3.93–3.68
(m, 8H, piperazine), 3.60–3.47 (m, 8H, piperazine), 2.76 (s, 3H,
1-(4-((5-(4-(4-(4-Phenylpiperazin-1-yl)quinazolin-2-yl)piperazin-
1-yl)-1,3,4-oxadiazol-2-yl)thio)phenyl)ethanone (9g). Yield: 69%;
mp 257–260°C; IR (KBr) cmÀ1: 2987 (aromatic C–H), 1734
(C=O acetyl), 1676 (C=N oxadiazole ring), 1226 (oxadiazole C–
Ar–CH3); 13C NMR (100 MHz, DMSO)
δ
174.48
1
O–C); H NMR (400 MHz, DMSO) δ 7.79–7.57 (m, 4H, Ar–H),
(oxadiazole C–S–Ar), 167.34 (quinazoline ring N=C–N C2
position), 166.29 (quinazoline C4 position), 157.49
(quinazoline ring C=C–N), 155.54 (oxadiazole C–N
piperazine), 152.20 (Ar–C), 137.15, 135.24, 134.19, 133.59,
132.07, 130.16, 128.94, 127.04, 126.31, 124.43, 122.63,
120.16 (16 Ar–C), 48.86, 47.27, 46.35, 45.17 (8C of
piperazine), 26.49 (Ar–CH3); MS (m/z): 565.6 [M+]. Anal.
Calcd. for C31H32N8OS: C, 65.93; H, 5.71; N, 19.84.
Found: C, 65.76; H, 5.72; N, 19.78.
7.42–6.86 (m, 5H, Ar–H), 6.83–6.62 (m, 4H, Ar–H), 3.85–3.61
(m, 8H, piperazine), 3.53–3.34 (m, 8H, piperazine), 2.28 (s, 3H,
Ar–COCH3); 13C NMR (100 MHz, DMSO) δ 196.80 (–C=O),
171.97 (oxadiazole C–S–Ar), 164.01 (quinazoline ring N=C–N
C2 position), 163.13 (quinazoline C4 position), 155.72
(quinazoline ring C=C–N), 151.56 (oxadiazole C–N piperazine),
140.68 (Ar–C), 134.85, 132.18, 129.83, 127.12, 126.88, 126.32,
125.92, 124.93, 123.84 (16 Ar–C), 49.47, 48.12, 47.32, 46.75
(8C of piperazine), 26.58 (acetophenone –CH3); MS (m/z): 551.8
[M+]. Anal. Calcd. for C32H32N8O2S: C, 64.84; H, 5.44; N, 18.91.
Found: C, 64.65; H, 5.42; N, 18.88.
2-((2-Nitrophenyl)thio)-5-(4-(4-(4-phenylpiperazin-1-yl)
quinazolin-2-yl)piperazin-1-yl)-1,3,4-oxadiazole (9d). Yield: 74%;
mp 143–147 °C; IR (KBr) cmÀ1: 2950 (aromatic C–H), 1674 (C=N
oxadiazole ring), 1567 (N–O of nitro), 1378 (N–O of nitro), 1138
4-((5-(4-(4-(4-Phenylpiperazin-1-yl)quinazolin-2-yl)piperazin-
1-yl)-1,3,4-oxadiazol-2-yl)thio)benzoic acid (9h). Yield: 72%;
mp 134–137 °C; IR (KBr) cmÀ1: 2994 (aromatic C–H), 1746
(C=O acetyl), 1684 (C=N oxadiazole ring), 1264 (oxadiazole C–
O–C); 1H NMR (400 MHz, DMSO) δ 11.34 (s, 1H, Ar–COOH),
8.19-7.89 (m, 4H, Ar–H), 7.84–7.63 (m, 5H, Ar–H), 7.58–7.15
(m, 4H, Ar–H), 3.98–3.73 (m, 8H, piperazine), 3.67–3.30 (m,
1
(oxadiazole C–O–C); H NMR (400 MHz, DMSO) δ 8.05–7.73
(m, 4H, Ar–H), 7.64-7.13 (m, 5H, Ar–H), 7.06–6.72 (m, 4H, Ar-
H), 3.94–3.69 (m, 8H, piperazine), 3.64–3.33 (m, 8H, piperazine);
13C NMR (100MHz, DMSO) δ 173.22 (oxadiazole C–S–Ar),
166.24 (quinazoline ring N=C–N C2 position), 163.29
(quinazoline C4 position), 157.74 (quinazoline ring C=C–N),
154.21 (oxadiazole C–N piperazine), 151.16 (Ar–C), 146.61 (Ar–
C–NO2), 138.24, 135.57, 133.48, 131.08, 128.84, 125.43, 124.47,
122.26, 121.27, 120.16, 119.64, 118.15, 117.09 (15 Ar–C), 48.54,
47.15, 46.22, 45.27 (8C of piperazine); MS (m/z): 596.8 [M+].
Anal. Calcd. for C30H29N9O3S: C, 60.49; H, 4.91; N, 21.16.
Found: C, 60.32; H, 4.90; N, 21.19.
2-((3-Nitrophenyl)thio)-5-(4-(4-(4-phenylpiperazin-1-yl)
quinazolin-2-yl)piperazin-1-yl)-1,3,4-oxadiazole (9e). Yield: 70%;
mp 245–249 °C; IR (KBr) cmÀ1: 2977 (aromatic C–H), 1649 (C=N
oxadiazole ring), 1579 (N–O of nitro), 1367 (N–O of nitro), 1174
(oxadiazole C–O–C); 1H NMR (400 MHz, DMSO) δ 8.10–7.79
(m, 4H, Ar–H), 7.75–7.28 (m, 5H, Ar–H), 7.21–6.83 (m, 4H, Ar-H),
3.87–3.73 (m, 8H, piperazine), 3.68–3.45 (m, 8H, piperazine);
13C NMR (100 MHz, DMSO) δ 176.64 (oxadiazole C–S–Ar),
169.24 (quinazoline ring N=C–N C2 position), 165.11
(quinazoline C4 position), 158.26 (quinazoline ring C=C–N),
8H, piperazine); 13C NMR (100 MHz, DMSO)
δ 179.25
(oxadiazole C–S–Ar), 170.14 (Ar–COOH), 169.41 (quinazoline
ring N=C–N C2 position), 164.11 (quinazoline C4 position),
157.72 (quinazoline ring C=C–N), 154.34 (oxadiazole C–N
piperazine), 143.28 (Ar–C), 138.24, 135.43, 130.17, 128.60,
127.34, 126.54, 125.30, 124.11, 123.39, 122.46, 121.41, 120.13
(16 Ar-C), 52.24, 51.82, 50.12, 49.65 (8C of piperazine); MS
(m/z): 595.7 [M+]. Anal. Calcd. for C31H30N8O3S: C, 62.61; H,
5.08; N, 18.84. Found: C, 62.53; H, 5.09; N, 18.86.
4-((5-(4-(4-(4-Phenylpiperazin-1-yl)quinazolin-2-yl)piperazin-1-
yl)-1,3,4-oxadiazol-2-yl)thio)benzonitrile (9i).
Yield: 78%; mp
212–215 °C; IR (KBr) cmÀ1: 2977 (aromatic C–H), 2257 (CN),
1750 (C=O acetyl), 1649 (C=N oxadiazole ring), 1281 (oxadiazole
C–O–C); 1H NMR (400 MHz, DMSO) δ 7.96–7.74 (m, 4H, Ar-H),
7.68–7.37 (m, 5H, Ar–H), 7.34–6.99 (m, 4H, Ar-H), 3.52–3.40 (m,
8H, piperazine), 3.38–3.19 (m, 8H, piperazine); 13C NMR
(100 MHz, DMSO)
δ
173.26 (oxadiazole C–S–Ar), 172.55
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet