Nov-Dec 2008
Synthesis of 2,4-Disubstituted-1,2,4-triazolo[1,5-a]quinazolin-5(4H)-ones
1827
derivatives 3a-h prepared are listed in the following together
with their physical constants and spectral data.
235 (53), 118 (26), 92 (30), 77 (64), 51 (100). Anal Calcd.
for C19H14N4O2 (330.35): C, 69.08; H, 4.27; N, 16.96. Found:
C, 69.15; H, 4.21; N, 16.91 %.
Benzaldehyde N-(3-phenyl-4-oxoquinazolin-2-yl)-hydra-
zone (3a). Colorless crystals (yield 86%), m.p. 226-228°C
(ethanol), Lit. m.p. 232°C [10], 205-206°C [18]. IR: (KBr) ꢀ
2-Thiophenealdehyde N-(3-phenyl-4-oxoquinazolin-2-yl)-
hydrazone (3h). pale brown crystals (yield 82%), m.p. 252°C
(ethanol-dioxane). IR: (KBr) ꢀ 3349, 1698, 1614 cm-1. 1H NMR
(DMSO): ꢁ 6.9 (d, 1H, J = 4 Hz, thienyl-C3-H), 7.3 (dd, 1H, J 4
Hz, thienyl-C4-H), 7.6 (d, 1H, J = 4 Hz, thienyl-C5-H), 7.6 – 8.5
(m, 9 H, ArH), 8.21 (s, 1H, -N=CH), 10.29 (s, 1H, NH). MS:
m/z (%): 347 (M++1, 19), 346 (M+, 82), 235 (53), 193 (14), 166
(12), 144 (16), 119 (40), 109 (20), 95 (94), 77 (100). Anal
Calcd. for C19H14N4OS (346.41): C, 65.88; H, 4.07; N, 16.17.
Found: C, 65.77; H, 4.27; N, 15.96 %.
1,4-Disubstituted-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-
ones (5). General procedure. To a solution of the appropriate
aldehyde hydrazone 3 (2.5 mmole) in ethanol (150 mL), was
added a solution of ferric chloride (2 M, 2 mL) and the mixture
was refluxed for 30 min then left overnight at room temperature.
The solution was evaporated under reduced pressure and water
was added to it. The solid that precipitated was collected by
filtration, washed with water, dried and finally crystallized from
ethanol to give the respective 1,4-substituted-1,2,4-triazolo[4,3-
a]quinazolin-5(4H)-one 5. The compounds prepared together
with their physical constants and spectral data are listed below.
1,4-Diphenyl-1,2,4-triazolo[4,3-a]quinazolin-5(4H)-one (5a).
Colorless crystals (yield 60%), m.p. 267°C (ethanol), (Lit. m.p.
238°C [10]),. IR: (KBr) ꢀ 1691, 1607 cm-1. 1H NMR (DMSO): ꢁ
7.11 (d, 2H, ArH), 7.52 - 7.73 (m, 10H, ArH), 8.3 (d, 2H, ArH).
MS: m/z (%): 339 (M++1, 16), 338 (M+, 67), 234 (66), 205 (10),
178 (55), 103 (44), 101 (15), 77 (72), 76 (100). Anal Calcd. for
C21H14N4O (338.37): C, 74.54; H, 4.17; N, 16.56. Found: C,
74.64; H, 4.32; N, 16.57 %.
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3426, 3344, 1697, 1612 cm-1. H NMR (DMSO): ꢁ 7.10 – 8.0
(m, 14 H, ArH), 8.10 (s, 1H, -N=CH), 10.5 (s, 1H, NH). MS:
m/z (%): 341 (M++1, 13), 340 (M+, 49), 339 (60), 263 (93), 235
(55), 192 (10), 118 (27), 91 (37), 89 (100), 77 (93), 62 (36).
Anal Calcd. for C21H16N4O (340.39): C, 74.10; H, 4.74; N,
16.46. Found: C, 73.94; H, 4.77; N, 16.53 %.
4-Bromobenzaldehyde N-(3-phenyl-4-oxoquinazolin-2-yl)-
hydrazone (3b). Pale yellow crystals (yield 85%), m.p. 285°C
(ethanol-dioxane). IR: (KBr) ꢀ 3215, 1667, 1618 cm-1. 1H NMR
(DMSO): ꢁ 7.31 – 7..80 (m, 9 H, ArH), 7.35 (d, 2H, ArH), 7.90
(d, 2H, ArH), 8.00 (s, 1H, -N=CH), 10.60 (s, 1H, NH). MS: m/z
(%): 421 (M++2, 11), 420 (M++1, 42), 419 (M+, 18), 263 (100),
236 (58), 193 (15), 119 (27), 90 (27), 77 (44). Anal Calcd. for
C21H15BrN4O (419.28): C, 60.16; H, 3.61; N, 13.36. Found: C,
60.15; H, 3.65; N, 13.38 %.
4-Nitrobenzaldehyde N-(3-phenyl-4-oxoquinazolin-2-yl)-
hydrazone (3c). Orange crystals (yield 86%), m.p. 269°C
(ethanol-dioxane), Lit. m.p. 260-262°C [18], IR: (KBr) ꢀ 3350,
1
1692, 1618 cm-1. H NMR (DMSO): ꢁ 7.20 – 7.85 (m, 9 H,
ArH), 7.90 (d, 2H, ArH), 8.15 (d, 2H, ArH), 8.25 (s, 1H, -
N=CH), 10.73 (s, 1H, NH). MS: m/z (%): 386 (M++1, 14), 385
(M+, 48), 262 (100), 235 (51), 192 (12), 119 (44), 91 (37), 77
(74), Anal Calcd. for C21H15N5O3 (385.39): C, 65.45; H, 3.92; N,
18.17. Found: C, 65.35; H, 4.21; N, 18.03 %.
4-Methoxybenzaldehyde N-(3-phenyl-4-oxoquinazolin-2-
yl)hydrazone (3d). Colorless crystals (yield 90%), m.p. 236°C
(ethanol), Lit. m.p. 238°C [10], 274-276°C [18]. IR: (KBr) ꢀ
3235, 1696, 1618 cm-1. 1H NMR (DMSO): ꢁ 3.88 (s, 3H,
OCH3), 7.10 (d, 2H, ArH), 7.50 – 7.90 (m, 9 H, ArH), 8.00 (s,
1H, -N=CH), 8.26 (d, 2H, ArH), 10.49 (s, 1H, NH). MS: m/z
(%): 371 (M++1, 34), 370 (M+, 100), 263 (57), 236 (66), 120
(29), 91 (27), 77 (48). Anal Calcd. for C22H18N4O2 (370.40): C,
71.34; H, 4.90; N, 15.13. Found: C, 71.64; H, 5.18; N, 15.30 %.
4-Dimethylaminobenzaldehyde N-(3-phenyl-4-oxoquinaz-
olin-2-yl)-hydrazone (3e). Orange crystals (yield 81%), m.p.
260°C (ethanol-dioxane). IR: (KBr) ꢀ 3328, 1689, 1606 cm-1. 1H
NMR (DMSO): ꢁ 3.00 (s, 6H, N(CH3)2), 6.68 – 7.74 (m, 13 H,
ArH), 7.86 (s, 1H, -N=CH), 10.40 (s, 1H, NH). MS: m/z (%):
384 (M++1, 73), 383 (M+, 100), 382 (21), 263 (25), 236 (58),
223 (14), 146 (63), 132 (49), 91 (21), 77 (34). Anal Calcd. for
C23H21N5O (383.46): C, 72.04; H, 5.52; N, 18.26. Found: C,
72.37; H, 5.23; N, 18.48 %.
1-Naphthaldehyde N-(3-phenyl-4-oxoquinazolin-2-yl)hy-
drazone (3f). pale green crystals (yield 82%), m.p. 230°C
(ethanol-dioxane). IR: (KBr) ꢀ 3342, 1684, 1613 cm-1. 1H NMR
(DMSO): ꢁ 7.13 – 8.67 (m, 16 H, ArH), 8.77 (s, 1H, -N=CH),
10.67 (s, 1H, NH). MS: m/z (%): 391 (M++1, 28), 390 (M+, 72),
263 (100), 236 (75), 140 (46), 127 (15), 119 (12), 91 (12), 77
(32). Anal Calcd. for C25H18N4O (390.45): C, 76.91; H, 4.65; N,
14.35. Found: C, 77.01; H, 4.36; N, 14.32 %.
1-(4-Bromophenyl)-4-phenyl-1,2,4-triazolo[4,3-a]quinazol-
in-5(4H)-one (5b). Pale yellow crystals (yield 64%), m.p. 285°C
1
(ethanol). IR: (KBr) ꢀ 1680, 1611 cm-1. H NMR (CDCl3): ꢁ
7.27 -8.94 (m, ArH). MS: m/z (%): 419 (M++2, 6), 418 (M++1,
27), 417 (M+, 33), 258 (12), 234 (56), 177 (19), 103 (19), 77
(58), 76 (100). Anal Calcd. for C21H13BrN4O (417.27): C, 60.45;
H, 3.14; N, 13.43. Found: C, 60.58; H, 3.03; N, 13.48 %.
1-(4-Nitrophenyl)-4-phenyl-1,2,4-triazolo[4,3-a]quinazolin-
5(4H)-one (5c). Orange crystals (yield 57%), m.p. 310°C
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(ethanol). IR: (KBr) ꢀ 1683, 1608 cm-1. H NMR (DMSO): ꢁ
7.15 – 8.04 (m, ArH). MS: m/z (%): 384 (M++1, 30), 383 (M+,
30), 234 (49), 224 (19), 177 (21), 103 (20), 77 (54), 76 (100).
Anal Calcd. for C21H13N5O3 (383.37): C, 65.79; H, 3.42; N,
18.27. Found: C, 65.86; H, 3.34; N, 18.54 %.
1-(4-Methoxyphenyl)-4-phenyl-1,2,4-triazolo[4,3-a]quinaz-
olin-5(4H)-one (5d). Colorless crystals (yield 68%), m.p. 290°C
(ethanol), (Lit. m.p. 282°C [10]). IR (KBr) ꢀ 1681, 1612 cm-1.
1H NMR (CDCl3): ꢁ 3.94 (s, 3H, CH3O), 7.09 – 8.66 (m, 13H,
ArH). MS: m/z (%): 369 (M++1, 9), 368 (M+, 34), 367 (43),
234 (44), 165 (10), 132 (36), 102 (43), 90 (41), 77 (58), 75
(100). Anal Calcd. for C22H16N4O2 (368.40): C, 71.73; H, 4.38;
N, 15.21. Found: C, 71.90; H, 4.43; N, 15.31 %.
1-(4-Dimethylaminophenyl)-4-phenyl-1,2,4-triazolo[4,3-a]-
quinazolin-5(4H)-one (5e). Orange crystals (yield 66%), m.p.
280°C (ethanol). IR: (KBr) ꢀ 1685, 1614 cm-1. 1H NMR
(CDCl3): ꢁ 3.09 (s, 6H, (CH3)2N), 6.83 – 8.42 (m, 13H, ArH).
MS: m/z (%): 382 (M++1, 17), 381 (M+, 64), 380 (100), 234
(18), 145 (50), 144 (50), 103 (20), 77 (28), 76 (50), 75 (65).
Anal Calcd. for C23H19N5O (381.44): C, 72.42; H, 5.02; N,
18.36. Found: C, 72.48; H, 5.13; N, 18.51 %.
2-Furfuraldehyde N-(3-phenyl-4-oxoquinazolin-2-yl)hydra-
zone (3g).
colorless crystals (yield 66%), m.p. 214°C
(ethanol). IR: (KBr) ꢀ 3210, 1681, 1629 cm-1. 1H NMR
(DMSO): ꢁ 6.6 (dd, 1H, J = 4 Hz, Furyl-C4-H), 6.8 (d, 1H,
J=4 Hz, Furyl-C3-H), 7.7 (d, 1H, J = 4 Hz, Furyl-C5-H), 7.55
(-8.50 (m, 9H, Ar-H), 7.90 (s, 1H, -N=CH), 10.40 (s, 1H,
NH). MS: m/z (%): 331 (M++1, 12), 330 (M+, 59), 329 (72),