1924 Swamy et al.
Asian J. Chem.
amidoxime 2c following general procedure-IV method-A
(80 % yield). Cream colour solid; IR (KBr, νmax, cm-1): 3118
(NH), 1621 (C=N), 1569, 1361, 961, 750; 1H NMR (300 MHz,
DMSO-d6): δ 10.35 (s, 1H, -NH), 8.89 (s, 1H, -CH=N), 8.15
(d, 1H, J = 7.5 Hz, Ar-H), 8.05 (d, 2H, J = 9.0 Hz, Ar-H), 7.77
(d, 1H, J = 8.4 Hz,Ar-H), 7.57 (dd, 1H, J = 8.1, 7.5 Hz,Ar-H),
7.46-7.35 (m, 2H, Ar-H), 2.48 (s, 3H, -CH3); 13C NMR (75
MHz, DMSO-d6): δ 175.10, 168.68, 140.77, 139.00, 133.73,
132.60, 129.46, 127.93, 126.48, 126.33, 124.70, 122.47,
119.86, 116.09, 115.44, 21.25; HRMS: m/z (M + Na) calcd.
for C16H12N4ONa: 299.0909; Found (M + Na)+: 299.0919; ESI-
MS m/z 277 (M + H)+.
3-(3-Fluorophenyl)-5-(5-indazolyl)-1,2,4-oxadiazole
(5d): Compound 5d was prepared from compound 5 and
amidoxime 2d following general procedure-IV method-A (60
% yield). Light yellow colour solid; IR (KBr, νmax, cm-1): 3143
(NH), 2928, 1626 (C=N), 1457, 956, 758; 1H NMR (300 MHz,
DMSO-d6): δ 13.54 (s, 1H, -NH), 8.71 (s, 1H, -CH=N), 8.32
(s, 1H, Ar-H), 8.09 (t, 1H, J = 8.76, Ar-H), 7.94 (d, 1H, J = 7.8
Hz, Ar-H), 7.85-7.76 (m, 2H, Ar-H), 7.69-7.62 (m, 1H, Ar-
H), 7.50-7.44 (m, 1H, Ar-H); 13C NMR (75 MHz, DMSO-d6):
δ 176.75, 167.67, 164.30, 161.06, 141.84, 135.88, 132.04,
131.93, 128.96, 128.84, 125.42, 123.69, 123.66, 123.32,
122.99, 119.03, 118.75, 115.87, 114.27, 113.96, 111.83; ESI-
MS m/z 281 (M + H)+.
3-(3-Fluorophenyl)-5-(4-indazolyl)-1,2,4-oxadiazole (4d):
Compound 4d was prepared from compound 4 and amidoxime
2d following general procedure-IV method-A (70 % yield).
Half-white colour solid; IR (KBr, νmax, cm-1): 3161 (NH), 1604
3-Methyl-5-(6-indazolyl)-1,2,4-oxadiazole (6a): Com-
pound 6a was prepared from compound 6 and amidoxime 2a
following general procedure-IV method-A (85 % yield). Light
yellow colour solid; IR (KBr, νmax, cm-1): 3211 (NH), 1591
1
(C=N), 1566, 1362, 961, 754; H NMR (300 MHz, DMSO-
1
d6): δ 13.63 (s, 1H, -NH), 8.70 (s, 1H, -CH=N), 8.04 (t, 2H,
J = 4.5 Hz, Ar-H), 7.95 (d, 2H, J = 8.5 Hz, Ar-H), 7.70-7.57
(m, 2H, Ar-H), 7.52-7.45 (m, 1H, Ar-H); 13C NMR (75 MHz,
DMSO-d6): δ 175.34, 167.69, 167.66, 164.25, 161.01, 140.81,
133.58, 131.83, 131.72, 129.71, 128.60, 126.19, 123.65,
123.61, 122.48, 119.78, 118.96, 118.68, 116.25, 115.18,
114.31, 114.00; HRMS: m/z (M) calcd. for C15H9N4OF:
280.2636; Found (M)+: Not ionized; ESI-MS m/z 281
(M + H)+.
(C=N), 1571, 1333, 940, 774; H NMR (300 MHz, DMSO-
d6): δ 13.51 (s, 1H, -NH), 8.22 (d, 2H, J = 7.4 Hz, -CH=N),
7.98 (d, 1H, J = 8.4 Hz, Ar-H), 7.77 (dd, 1H, J = 8.4, 1.2 Hz,
Ar-H), 2.41 (s, 3H, -CH3); 13C NMR (75 MHz, DMSO-d6): δ
175.58, 168.00, 139.64, 134.35, 125.47, 122.28, 121.08,
119.27, 110.73, 11.60; HRMS: m/z (M + H) calcd. for
C10H8N4O: 201.0776; Found (M + H)+: 201.0766; ESI-MS
m/z 201 (M + H)+.
3-Phenyl-5-(6-indazolyl)-1,2,4-oxadiazole (6b): Com-
pound 6b was prepared from compound 6 and amidoxime 2b
following general procedure-IV method-A (90 % yield).
Brown colour solid; IR (KBr, νmax, cm-1): 3294 (NH), 1597
3-Methyl-5-(5-indazolyl)-1,2,4-oxadiazole (5a): Com-
pound 5a was prepared from compound 5 and amidoxime 2a
following general procedure-IV method-A (65 % yield). Light
yellow colour solid; m.p.: 204-205 °C; IR (KBr, νmax, cm-1):
3143 (NH), 2924, 1626 (C=N), 1392, 952, 755; 1H NMR (300
MHz, DMSO-d6): δ 13.49 (s, 1H, -NH), 8.58 (s, 1H, -CH=N),
8.27 (s, 1H, Ar-H), 8.00 (dd, 1H, J = 8.7, 1.5 Hz, Ar-H), 7.71
(d, 1H, J = 8.7 Hz, Ar-H), 2.39 (s, 3H, -CH3); 13C NMR (75
MHz, DMSO-d6): δ 175.71, 167.85, 141.67, 135.70, 125.23,
123.25, 122.48, 116.19, 111.71, 11.63; ESI-MS m/z 201 (M + H)+.
3-Phenyl-5-(5-indazolyl)-1,2,4-oxadiazole (5b): Com-
pound 5b was prepared from compound 5 and amidoxime 2b
following general procedure-IV method-A (75 % yield). Cream
colour solid; m.p.: 204-205 °C; IR (KBr, νmax, cm-1): 3144
(NH), 2928, 1568 (C=N), 1369, 954, 752; 1H NMR (300 MHz,
DMSO-d6): δ 13.53 (s, 1H, -NH), 8.70 (s, 1H, -CH=N), 8.32
(s, 1H, Ar-H), 8.13-8.08 (m, 3H, Ar-H), 7.77 (d, 1H, J = 8.8
Hz, Ar-H), 7.61-7.57 (m, 3H, Ar-H); 13C NMR (75 MHz,
DMSO-d6): δ 176.46, 168.53, 141.78, 135.83, 131.92, 129.60,
127.45, 126.72, 125.40, 123.31, 122.86, 116.05, 111.79; ESI-
MS m/z 263 (M + H)+.
1
(C=N), 1445, 1361, 742, 684; H NMR (300 MHz, DMSO-
d6): δ 13.56 (s, 1H, -NH), 8.37 (s, 1H, -CH=N), 8.26 (s, 1H,
Ar-H), 8.11 (t, 1H, J = 4.8 Hz, Ar-H), 8.03 (d, 1H, J = 8.4 Hz,
Ar-H), 7.88 (d, 1H, J = 8.1 Hz, Ar-H), 7.61 (t, 4H, J = 3.9, Ar-
H); 13C NMR (75 MHz, DMSO-d6): δ 176.35, 168.66, 139.63,
134.41, 132.01, 129.62, 127.48, 126.57, 125.62, 122.42,
120.98, 119.45, 111.11; ESI-MS m/z 263 (M + H)+.
3-(3-Methylphenyl)-5-(6-indazolyl)-1,2,4-oxadiazole
(6c): Compound 6c was prepared from compound 6 and amido-
xime 2c following general procedure-IV method-A (75 %
yield). Off-white colour solid; m.p.: >220 °C; IR (KBr, νmax
,
1
cm-1): 3434 (NH), 1597 (C=N), 1572, 1354, 754; H NMR
(300 MHz, DMSO-d6): δ 13.5 (s, 1H, -NH), 8.36 (s, 1H,
-CH=N), 8.25 (s, 1H, Ar-H), 8.02 (d, 1H, J = 8.4 Hz, Ar-H),
7.93-7.86 (m, 3H, Ar-H), 7.51-7.41 (m, 2H, Ar-H), 2.41 (s,
3H, -CH3); 13C NMR (75 MHz, DMSO-d6): δ 176.25, 168.70,
139.67, 139.01, 134.41, 132.62, 129.50, 127.86, 126.48,
125.61, 124.63, 122.40, 121.00, 119.45, 111.05, 21.25;
HRMS: m/z (M + H) calcd. for C16H12N4O: 277.1089; Found
(M + H)+: 277.1265; ESI-MS m/z 277 (M + H)+.
3-(3-Methylphenyl)-5-(5-indazolyl)-1,2,4-oxadiazole
(5c): Compound 5c was prepared from compound 5 and
amidoxime 2c following general procedure-IV method-A
(70 % yield). Off-white colour solid; IR (KBr, νmax, cm-1): 3146
(NH), 2926, 1627, 1603 (C=N), 1370, 955, 756; 1H NMR (300
MHz, DMSO-d6): δ 13.53 (s, 1H, -NH), 8.70 (s, 1H, -CH=N),
8.32 (s, 1H, Ar-H), 8.11(d, 1H, J = 8.8 Hz, Ar-H), 7.89 (d, 2H,
J = 12.1 Hz, Ar-H), 7.76 (d, 1H, J = 8.7 Hz, Ar-H), 7.49-7.40
(m, 2H,Ar-H), 2.46 (s, 3H, -CH3); 13C NMR (75 MHz, DMSO-
d6): δ 176.37, 168.57, 141.79, 138.97, 135.83, 132.52, 129.47,
127.85, 126.66, 125.39, 124.59, 123.32, 122.83, 116.07,
111.76, 21.25; ESI-MS m/z 277 (M + H)+.
3-(3-Fluorophenyl)-5-(6-indazolyl)-1,2,4-oxadiazole
(6d): Compound 6d was prepared from compound 6 and amido-
xime 2d following general procedure-IV method-A (72 %
yield). Cream colour solid; m.p.: >220 °C; IR (KBr, νmax, cm-1):
3444 (NH), 2868, 1601 (C=N), 1570, 1365, 956, 755; 1H NMR
(300 MHz, DMSO-d6): δ 13.58 (s, 1H, -NH), 8.37 (s, 1H,
-CH=N), 8.26 (s, 1H, Ar-H), 8.02 (t, 1H, J = 8.1 Hz, Ar-H),
7.97-7.94 (m, 2H, Ar-H), 7.89-7.82 (m, 2H, Ar-H), 7.69-7.62
(m, 1H, Ar-H), 7.51-7.45 (m, 1H, Ar-H); 13C NMR (75 MHz,
DMSO-d6): δ 176.57, 167.78, 167.74, 164.27, 161.02, 139.70,