Article
Suhasini et al.
with stirring. The obtained crude compound (3) was washed with
cold water, dried and recrystallized from boiling water. White
powder, Yield: 75%, m.p.: 245 °C, IR (KBr, nmax, cm-1): 1191,
Ar-H), 7.49 (d, 2H, J = 8.8 Hz, Ar-H), 7.62 (d, 2H, J = 8.8 Hz,
Ar-H). 13C NMR (75 MHz, DMSO) d: 23.0, 55.5, 110.5, 126.4,
128.0, 131.1, 132.1, 134.6, 142.2, 158.1, 166.8, 173.8. ESI-MS
(m/z): 293 (M+), Anal. Cald. for C18H15NO3: C, 73.71; H, 5.15; N,
4.78%; Found C, 73.73; H, 5.18; N, 4.75%. 4-(2,5-Dimethoxy
benzylidene)-2-p-tolyl oxazol-5(4H)-one (5d): Bright yellow
crystals, Yield: 79%, m.p.: 179 °C, IR (KBr, nmax, cm-1): 919,
1146, 1256, 1288, 1443, 1665, 2854. 1H NMR (400 MHz, CDCl3,
d, ppm): 2.38 (s, 3H, CH3), 3.81 (s, 3H, OCH3), 3.86 (s, 3H,
OCH3), 7.06 (s, 1H, =CH-), 7.22 (s, 1H, Ar-H), 7.28-7.33 (m, 2H,
Ar-H), 7.38 (d, 2H, J = 9.2 Hz, Ar-H), 7.41 (d, 2H, J = 8.8 Hz,
Ar-H). 13C NMR (75 MHz, DMSO) d: 23.1, 54.5, 58.2, 109.7,
120.9, 122.3, 124.4, 127.9, 132.1, 136.5, 143.1, 154.5, 158.2,
166.4, 172.6. ESI-MS (m/z): 323 (M+), Anal. Cald. for C19H17NO4:
C, 70.58; H, 5.30; N, 4.33%; Found C, 70.54; H, 5.28; N, 4.30%.
4-(2,4,6-Trimethoxy benzylidene)-2-p-tolyloxazol-5(4H)-one
(5e): Deep yellow crystals, Yield: 84%, m.p.: 174 °C, IR (KBr,
nmax, cm-1): 940, 1097, 1155, 1287, 1452, 1581, 1667, 1775, 2987.
1H NMR (400 MHz, CDCl3, d, ppm): 2.36 (s, 3H, CH3), 3.84 (s,
3H, OCH3), 3.93 (s, 3H, OCH3), 3.95 (s, 3H, OCH3), 6.48 (d, 1H,
J = 9.2 Hz, Ar-H), 7.15 (s, 1H, =CH-), 7.38 (d, 2H, J = 8.8 Hz,
Ar-H), 7.49 (d, 2H, J = 8.8 Hz, Ar-H), 7.72 (d, 1H, J = 8.8 Hz,
Ar-H). 13C NMR (75 MHz, DMSO) d: 23.7, 56.2, 60.9, 62.0,
107.6, 120.6, 126.2, 127.9, 129.6, 130.9, 135.0, 141.0, 154.7,
156.8, 158.0, 166.8, 173.8. ESI-MS (m/z): 353 (M+), Anal. Cald.
for C20H19NO5: C, 67.98; H, 5.42; N, 3.96%; Found C, 67.99; H,
5.40; N, 3.97%. 4-(4-Dimethylamino benzylidene)-2-p-tolyl-
oxazol-5(4H)-one (5f): Deep red crystals, Yield: 72%, m.p.: 178
°C, IR (KBr, nmax, cm-1): 957, 1159, 1243, 1376, 1428, 1586,
1
1431, 1543, 1675, 3072, 3272. H NMR (400 MHz, DMSO, d,
ppm): 2.75 (s, 3H, CH3), 3.72 (s, 2H, CH2), 7.33 (d, 2H, J = 8.4
Hz, Ar-H), 7.45 (d, 2H, J = 8.8 Hz, Ar-H), 8.15 (s, 1H, NH), 12.66
(br s, 1H, COOH). 13C NMR (75 MHz, DMSO) d: 22.8, 41.1,
127.6, 128.6, 132.4, 134.8, 170.5, 171.2; ESI-MS (m/z): 193
(M+), Anal. Cald. for C10H11NO3: C, 62.17; H, 5.74; N, 7.25%;
Found C, 62.15; H, 5.76; N, 7.21%.
General synthesis of 4-(substituted benzy-lidene)-2-p-
tolyloxazol-5(4H)-ones (5a-5l): A mixture of dry 2-(p-methyl
benzamido) acetic acid (3) (0.01 mol), substituted aromatic alde-
hyde (4a-4l) (0.01 mol), powdered anhydrous sodium acetate
(0.01 mol) and high-grade acetic anhydride (0.03 mol) was heated
at 110 °C with constant shaking. Then 4A° molecular sieves (2 g)
were added to the reaction mixture and heated on a water bath for
1 h with occasional stirring. After completion of the reaction, the
molecular sieves were removed by filtration and ethanol (10 mL)
was added slowly to the reaction mixture and left overnight at
room temperature. The crystalline product thus obtained was
?ltered, washed successively with cold alcohol, boiling water and
dried. The obtained 5-oxazolones (5a-5l) were recrystallized
from hot benzene. 4-Benzylidene-2-p-tolyloxazol-5(4H)-one
(5a): Yellow crystals, Yield: 78%, m.p.: 167 °C, IR (KBr, nmax
,
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cm-1): 964, 1134, 1476, 1657, 1756, 3028. H NMR (400 MHz,
CDCl3, d, ppm): 2.32 (s, 3H, CH3), 7.11 (s, 1H, =CH-), 7.28 (d,
2H, J = 8.8 Hz, Ar-H), 7.39 (d, 2H, J = 8.8 Hz, Ar-H), 7.53 (m, 3H,
Ar-H), 7.61 (d, 2H, J = 8.4 Hz, Ar-H). 13C NMR (75 MHz,
DMSO) d: 23.1, 110.6, 121.4, 121.6, 122.4, 122.9, 127.2, 128.7,
129.1, 133.4, 134.9, 141.6, 166.0, 174.9; ESI-MS (m/z): 263
(M+), Anal. Cald. for C17H13NO2: C, 77.55; H, 4.98; N, 5.32%;
Found: C, 77.50; H, 4.59; N, 5.30%. 4-(4-Methyl benzylidene)-
2-p-tolyloxazol-5(4H)-one (5b): Pale yellow crystals, Yield:
80%, m.p.: 173 °C, IR (KBr, nmax, cm-1): 960, 1158, 1455, 1562,
1666, 1789, 3014. 1H NMR (400 MHz, CDCl3, d, ppm): 2.39 (s,
3H, CH3), 2.44 (s, 3H, CH3), 7.07 (d, 2H, J = 8.4 Hz, Ar-H), 7.09
(s [merged with d], 1H, =CH-), 7.27-7.38 (m, 4H, Ar-H), 7.54 (d,
2H, J = 8.4 Hz, Ar-H). 13C NMR (75 MHz, DMSO) d: 21.9, 23.7,
112.3, 128.0, 129.5, 131.2, 132.5, 135.8, 143.2, 166.7, 174.1.
ESI-MS (m/z): 277 (M+), Anal. Cald. for C18H15NO2: C, 77.96; H,
5.45; N, 5.05%; Found C, 77.90; H, 5.43; N, 5.01%. 4-(4-
Methoxy benzylidene)-2-p-tolyloxazol-5(4H)-one (5c): Yellow
crystals, Yield: 82%, m.p.: 181 °C, IR (KBr, nmax, cm-1): 959,
1156, 1263, 1476, 1591, 1668, 1788, 2879. 1H NMR (400 MHz,
CDCl3, d, ppm): 2.36 (s, 3H, CH3), 3.87 (s, 3H, OCH3), 6.78 (d,
2H, J = 8.8 Hz, Ar-H), 7.08 (s, 1H, =CH-), 7.21 (d, 2H, J = 8.4 Hz,
1
1660, 3017. H NMR (400 MHz, CDCl3, d, ppm): 2.40 (s, 3H,
CH3), 3.09 (s, 6H, 2xCH3), 6.53 (d, 2H, J = 8.8 Hz, Ar-H), 7.07 (s,
1H, =CH-), 7.43-7.51 (m, 4H, Ar-H), 7.59 (d, 2H, J = 8.8 Hz,
Ar-H). 13C NMR (75 MHz, DMSO) d: 23.6, 40.1, 111.4, 121.5,
126.4, 128.2, 130.8, 133.6, 134.8, 135.9, 145.9, 167.4, 173.0.
ESI-MS (m/z): 306 (M+), Anal. Cald. for C19H18N2O2: C, 74.49;
H, 5.92; N, 9.14%; Found C, 74.45; H, 5.55; N, 9.12%. 4-(4-
Diethylamino benzylidene)-2-p-tolyloxazol-5(4H)-one (5g):
Orange red crystals, Yield: 70%, m.p.: 197 °C, IR (KBr, nmax
,
cm-1): 956, 1196, 1274, 1407, 1577, 1664, 1753, 2957. 1H NMR
(400 MHz, CDCl3, d, ppm): 1.22-1.26 (t, 6H, J = 6.8 Hz, 2xCH3),
2.38 (s, 3H, CH3), 3.42-3.48 (q, 4H, J = 7.2 Hz, 2xCH2), 6.51 (d,
2H, J = 8.8 Hz, Ar-H), 7.05 (s, 1H, =CH-), 7.38 (d, 2H, J = 8.8 Hz,
Ar-H), 7.49 (d, 2H, J = 8.8 Hz, Ar-H), 7.57 (d, 2H, J = 8.8 Hz,
Ar-H). 13C NMR (75 MHz, DMSO) d: 12.7, 23.6, 44.8, 111.1,
120.9, 126.0, 127.9, 130.7, 133.6, 135.2, 135.9, 150.1, 167.5,
172.8. ESI-MS (m/z): 334 (M+), Anal. Cald. for C21H22N2O2: C,
75.42; H, 6.63; N, 8.38%; Found C, 75.40; H, 6.60; N, 8.29%.
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© 2015 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
J. Chin. Chem. Soc. 2015, 62, 855-860