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Y.S. Kara / Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 149 (2015) 920–927
N-(4-fluorophenyl)-benzamide oxime (2e). Yield 57%; mp 147.5–
149 °C; IR (KBr),
(cmꢁ1): 3353.87 (NH), 3153.77–3104.13 (OH),
4-(4-fluorophenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-one (3e). Yield
64%; mp 160–161 °C; IR (KBr),
(cmꢁ1): 1773.12 (C@O), 1598.58
m
m
1627.11 (C@N). HRMS for
C
13H11N2OF [M+H]+ calculated
(C@N); 1H NMR (CDCl3), d (ppm): 7.53–7.49 (tt, J = 7.2, J = 1.6, aro-
matic, H), 7.41–7.34 (m, aromatic, 4H), 7.27–7.20 (m, aromatic,
2H), 7.16–7.11 (m, aromatic, 2H); 13C NMR (CDCl3), d (ppm):
158.23 (C@O), 157.42 (C@N), 163.96–116.88 (aromatic C). Anal.
Calcd for C14H9FN2O2 (256.23): C, 65.62; H, 3.54; N, 10.93. Found
C, 65.79; H, 3.65; N, 10.93. HRMS for C14H9N2O2F [M+Na]+ calcu-
lated 279.0540. Found 279.0531.
231.0928. Found 231.0915.
N-(4-chlorophenyl)-p-bromobenzamide oxime (2f). Yield 49%; mp
182.5–183.6 °C; IR (KBr),
m
(cmꢁ1): 3393.59 (NH), 3186.77–
3068.74 (OH), 1643.29 (C@N). HRMS for C13H11N2OCl [M+H]+ cal-
culated 247.0633. Found 247.0621.
N-(4-(trifluoromethyl)phenyl)-benzamide oxime (2g). Yield 50%; mp
99–101 °C; IR (KBr),
1626.17 (C@N). HRMS for
m
(cmꢁ1): 3386.45 (NH), 3142.41 (OH),
4-(4-chlorophenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-one (3f). Yield
C
14H11N2OF3 [M+H]+ calculated
69%; mp 159.5–160.9 °C; IR (KBr), m
(cmꢁ1): 1770.51 (C@O),
281.0896. Found 281.0899.
1594.38 (C@N); 1H NMR (CDCl3), d (ppm): 7.56–7.52 (tt, J = 7.2,
J = 1.2, aromatic, 2H), 7.45–7.36 (m, aromatic, 5H), 7.21–7.17 (tt,
J = 8.8, J = 2, aromatic, 2H); 13C NMR (CDCl3), d (ppm): 158.00
(C@O), 157.30 (C@N), 135.57–122.74 (aromatic C). Anal. Calcd for
N-(3-(trifluoromethyl)phenyl)-benzamide oxime (2h). Yield 50%;
mp 100.5–102.7 °C: IR (KBr),
m
(cmꢁ1): 3386.37 (NH), 3151.68–
3060.41 (OH), 1635.74 (C@N). HRMS for C14H11N2OF3 [M+H]+ cal-
culated 281.0896. Found 281.0894.
C
14H9ClN2O2 (272.67): C, 61.66; H, 3.33; N, 10.27. Found C,
N-(3-fluorophenyl)-benzamide oxime (2i). Yield 53%; mp 149–
61.44; H, 3.18; N, 10.23. HRMS for C14H9N2O2Cl [M+Na]+ calculated
295.0245. Found 295.0243.
151 °C; IR (KBr),
m
(cmꢁ1): 3399.26 (NH), 3153.77–3104.13 (OH),
1636.69 (C@N). HRMS for C13H11N2OF [M+H]+ calculated
231.0928. Found 231.0938.
3-phenyl-4-[4-(trifluoromethyl)phenyl]-1,2,4-oxadiazol-5(4H)-one
(3g). Yield 63%; mp 105–106 °C; IR (KBr),
m
(cmꢁ1): 1765.75
N-(3-chlorophenyl)-benzamide oxime (2j). Yield 52%; mp 106–
(C@O), 1601.67 (C@N); 1H NMR (CDCl3), d (ppm): 7.71–7.70 (d,
J = 7.2, aromatic, 1H), 7.60–7.50 (m, aromatic, 3H), 7.43–7.39 (t,
J = 8, aromatic, 3H), 7.35–7.33 (d, J = 7.2, aromatic, 2H); 13C NMR
(CDCl3), d (ppm): 157.74 (C@O), 157.20 (C@N), 132.59–122.54
(aromatic C). Anal. Calcd for C15H9F3N2O2 (306.23): C, 58.83; H,
2.96; N, 9.15. Found C, 58.72; H, 2.67; N, 8.77. HRMS for
108 °C; IR (KBr),
m
(cmꢁ1): 3374.45 (NH), 3157.46–3059.50 (OH),
1633.81 (C@N). HRMS for C13H11N2OCl [M+H]+ calculated
247.0633. Found 247.0644.
3,4-diphenyl-1,2,4-oxadiazol-5(4H)-one (3a) (general procedure)
Triethylamine (0.6 g, 6 mmol) was added to a stirred solution of
N-phenyl-benzamide oxime (2a) (1.27 g, 6 mmol) in xylene
(15 mL) at r.t., and then ethyl chloroformate was added dropwise
(0.72 g, 6 mmol) in xylene (10 mL) and the mixture was refluxed
for 9 h. The reaction mixture was filtered through filter paper,
and the solution was evaporated at reduced pressure. The crude
reaction product was crystallized in ethyl acetate/petroleum ether
C
15H9N2O2F [M+Na]+ calculated 329.0508. Found 329.0487.
3-phenyl-4-[3-(trifluoromethyl)phenyl]-1,2,4-oxadiazol-5(4H)-one
(3h). Yield 68%; mp 105–106.2 °C; IR (KBr),
(cmꢁ1): 1773.06
m
(C@O), 1607.29 (C@N); 1H NMR (CDCl3), d: 7.64–7.62 (d, J = 7.6,
aromatic, 1H), 7.53–7.43 (m, aromatic, 3H), 7.35–7.31 (t, J = 8, aro-
matic, 3H), 7.27–7.25 (d, J = 7.2, aromatic, 2H); 13C NMR (CDCl3), d
(ppm): 157.74 (C@O), 157.21 (C@N), 132.57–121.68, (aromatic C).
Anal. Calcd for C15H9F3N2O2 (306.23): C, 58.83; H, 2.96; N, 9.15.
Found C, 58.95; H, 2.39; N, 9.19. HRMS for C15H9N2O2F [M+Na]+
calculated 329.0508. Found 329.0494.
(1:3) to give (3a) (1.1 g, 72%); mp 171.3–171.6 °C; IR (KBr),
m
d
(cmꢁ1): 1771.30 (C@O), 1593.85 (C@N); 1H NMR (CDCl3),
(ppm): 7.51–7.46 (m, aromatic, 2H), 7.45–7.44 (t, J = 3.2, aromatic,
2H), 7.36–7.36 (d, J = 1.6, aromatic, 2H), 7.35 (s, aromatic, 2H),
7.24–7.21 (m, aromatic, 2H); 13C NMR (CDCl3), d (ppm): 158.34
(C@O), 157.53 (C@N), 131.99–123.04 (aromatic C). Anal. Calcd for
4-(3-fluorophenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-one (3i). Yield
71%; mp 129–132.5 °C; IR (KBr),
m
(cmꢁ1): 1780.91 (C@O),
1607.90 (C@N); 1H NMR (CDCl3), d (ppm): 7.55–7.50 (td, J = 7.2,
J = 1.6, aromatic, 1H), 7.44–7.33 (m, aromatic, 5H), 7.19–7.14 (m,
aromatic, 1H), 7.03–7.00 (dd, J = 6.8, J = 1.6 aromatic, 2H); 13C
NMR (CDCl3), d (ppm): 157.86 (C@O), 157.29 (C@N), 164.00–
114.39 (aromatic C). Anal. Calcd for C14H9FN2O2 (256.23): C,
65.62; H, 3.54; N, 10.93. Found C, 65.50; H, 3.56; N, 10.53. HRMS
for C14H9N2O2F [M+Na]+ calculated 279.0540. Found 279.0526.
4-(3-chlorophenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-one (3j). Yield
C
14H10N2O2 (238.24): C, 70.58; H, 4.23; N, 11.76. Found C, 70.63;
H, 4.63; N, 11.71. HRMS for C14H10N2O2 [M+Na]+ calculated
261.0635. Found 261.0637.
Spectroscopic and analytical data of compounds (3).
4-(4-methylphenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-one (3b). Yield
60%; mp 164.5–165.8 °C [41], Lit. 165–166 °C [42]; HRMS for
C
15H12N2O2 [M+Na]+ calculated 275.0731. Found 275.0785.
53%; mp 147–148.3 °C; IR (KBr), m
(cmꢁ1): 1769.96 (C@O),
4-(4-methoxyphenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-one
(3c).
1581.25 (C@N); 1H NMR (CDCl3), d (ppm): 7.55–7.51 (td, J = 7.2,
J = 1.6, aromatic, 1H), 7.44–7.34 (m, aromatik, 6H), 7.31–7.30 (t,
J = 3.2, aromatic, 1H), 7.09–7.07 (m, aromatik, 1H), 13C NMR
(CDCl3), d (ppm): 157.86 (C@O), 157.24 (C@N), 135.48–122.65
(aromatic C). Anal. Calcd for C14H9ClN2O2 (272.67): C, 61.66; H,
3.33; N, 10.27. Found C, 61.39; H, 3.17; N, 10.26. HRMS for
Yield 61%; mp 158.1–160.2 °C. IR (KBr),
m
(cmꢁ1): 1766.99 (C@O),
1606.21 (C@N). 1H NMR (CDCl3), d (ppm): 7.52–7.48 (m, aromatic,
1H), 7.39–7.38 (d, J = 3.6, aromatic, 4H), 7.18–7.15 (d, J = 8.8, aro-
matic, 2H), 6.96–6.94 (d, J = 8.8, aromatic, 2H), 3.84 (s, 3H, OCH3).
13C NMR (CDCl3), d (ppm): 158.69 (C@O), 157.64 (C@N), 160.25–
115.08 (aromatic C), 55.59 (OCH3). Anal. Calcd for C15H12N2O3
(268.27): C, 67.16; H, 4.51; N, 10.44. Found C, 67.34; H, 4.55; N,
10.39. HRMS for C15H12N2O3 [M+Na]+ calculated 291.0740. Found
291.0743.
C
14H9N2O2Cl [M+Na]+ calculated 295.0245. Found 295.0233.
3,4-diphenyl-1,2,4-oxadiazole-5(4H)-thione (4a) (general procedure)
Compound (3a) (1.1 g, 4.33 mmol) was refluxed with P2S5
(0.466 g, 2 mmol) in xylene for 35 h. The reaction mixture was fil-
tered and xylene was evaporated under reduced pressure. The
crude product was purified by flash column chromatography, using
ethyl acetate-petroleum ether (1:4) as eluent. The residue was
crystallized from ethanol. (Rf: 0.55). The product recrystallized
from ethanol to give (4a) (0.49 g, Yield 40%; mp 172–173.3 °C; IR
4-(4-bromophenyl)-3-phenyl-1,2,4-oxadiazol-5(4H)-one (3d). Yield
66%; mp 161–163 °C; IR (KBr),
m
(cmꢁ1): 1771.29 (C@O), 1603.04
(C@N); 1H NMR (CDCl3), d (ppm): 7.60–7.58 (d, J = 8.8, aromatic,
2H), 7.54–7.53 (d, J = 7.2, aromatic, H), 7.44–7.36 (m, aromatic,
4H), 7.14–7.11 (d, J = 8.8, aromatic, 2H); 13C NMR (CDCl3), d
(ppm): 157.90 (C@O), 157.23 (C@N), 133.07–122.74 (aromatic C).
Anal. Calcd for C14H9BrN2O2 (317.13): C, 53.02; H, 2.86; N, 8.83.
Found C, 53.22; H, 2.59; N, 8.87. HRMS for C14H9N2O2Br [M+Na]+
calculated 338.9740. Found 338.9719.
(KBr),
m
(cmꢁ1): 1590.95 (C@N), 1327.10 (C@S); 1H NMR (CDCl3),
d (ppm): 7.52–7.47 (m, aromatic, 4H), 7.38–7.26 (m, aromatic,
6H); 13C NMR (CDCl3), d (ppm): 187.26(C@S), 158.78 (C@N),