J IRAN CHEM SOC
1H NMR (400 MHz, DMSO) δ = 0.96 (s, 3H, CH3), 1.04
(s, 3H, CH3), 2.07 (d, 1H, J = 16.0 Hz, H-5), 2.20 (d, 1H,
J = 12.0 Hz, H’-5), 2.28 (s, 3H, CH3), 2.48–2.59 (m, 2H,
H-7), 6.16 (S, 1H, H-9), 7.07 (s, 4H, Ar–H), 7.67 (s, 1H,
H-2), 11.09 (s, 1H, NH).
R
N
NH2
N
H
3
O
N
N
N
N
N
H
O
CHO
+
4a-j
Acetic acid
60 °C
R
O
R
N
NH2
6,7‑dihydro‑9‑(2,4‑dimethoxyphenyl)‑6,6‑dimethyl‑[1,2,4]
triazolo[5,1‑b]quinazolin‑8(4H,5H,9H)‑one (4c)
O
1
2
N
H
N
R: H, Me, OMe, NO2, F, Cl, Br,...
5
N
N
H
White solid (88 % yield); m.p. 211–212 °C; IR (KBr,
cm−1): 3150, 3093, 3030, 2959, 2933, 1694, 1652, 1579,
1508, 1416, 1338, 1294, 1183, 1038, 826; 1H NMR
(400 MHz, CDCl3): δ 1.07 (s, 3H, CH3), 1.15 (s, 3H, CH3),
2.22 (d, J = 16.0 Hz, 1H, H-5), 2.29 (d, J = 16.0 Hz, 1H,
H’-5), 2.48 (d, J = 16.0 Hz, 1H, H-7), 2.59 (d, J = 16.0 Hz,
1H, H’-7), 3.71 (s, 3H, OCH3), 3.77 (s, 3H, OCH3), 6.40
(d, J = 2.4 Hz, 1H, Ar–H), 6.47 (dd, J = 8.0, 4.0 Hz, 1H,
Ar–H), 6.56 (s, 1H, H-9), 7.38 (d, J = 8.0 Hz, 1H, Ar–H),
7.64 (s, 1H, H-2), 11.76 (s, 1H, NH).
6a-h
Scheme 1 Synthesis of quinazolinones in the presence of acetic acid
as reaction medium
Experimental
General
Melting point and IR spectra of all compounds were
obtained on an Electrothermal 9100 apparatus and a JASCO
FT/IR-460 plus spectrometer, respectively. 1H and 13C NMR
spectra of compounds were recorded on a Bruker DRX-400
Avance instrument in DMSO or CDCl3 as the solvent with
TMS as internal standard at 400 MHz. Elemental analyses
for C, H, and N for the new compounds were performed
using a Heraeus CHN-O-Rapid analyzer. The mass spectra
for the new compounds were recorded on an Agilent Tech-
nology (HP) mass spectrometer, operating at an ionization
potential of 70 eV. All reagents were purchased from Merck
(Darmastadt, Germany), Acros (Geel, Belgium) and Fluka
(Buchs, Switzerland), and used without further purification.
6,7‑dihydro‑6,6‑dimethyl‑9‑(naphthalen‑2‑yl)‑[1,2,4]
triazolo[5,1‑b]quinazolin‑8(4H,5H,9H)‑one (4h)
White solid (98 % yield); m.p. 266–268 °C; IR (KBr,
cm−1): 3416, 3246, 3091, 2963, 2927, 1652, 1574, 1469,
1410, 1364, 1335, 1251, 779; 1H NMR (400 MHz,
DMSO): δ 0.97 (s, 3H, CH3), 1.05 (s, 3H, CH3), 2.06 (d,
J = 16.0 Hz, 1H, H-5), 2.23 (d, J = 16.0 Hz, 1H, H’-5),
2.58 (dd, J = 16.0, 24.0 Hz, 2H, H-7), 6.38 (S, 1H, H-9),
7.26 (dd, J = 4.0, 8.0 Hz, 1H, Ar–H), 7.48–7.50 (m, 2H,
Ar–H), 7.69 (s, 1H, H-2), 7.80 (d, J = 4.0 Hz, 1H, Ar–H),
7.84 (d, J = 8.0 Hz, 2H, Ar–H), 7.90 (t, J = 4.0 Hz, 1H,
Ar–H), 11.20 (s, 1H, NH).
General procedure for the preparation of [1,2,4]
triazolo[5,1-b]quinazolin-8(4H)-one and hexahydro[4,5]
benzimidazolo[2,1-b]quinazolinone derivatives
6,7‑dihydro‑9‑(2,3‑dimethoxyphenyl)‑6,6‑dimethyl‑[1,2,4]
triazolo[5,1‑b]quinazolin‑8(4H,5H,9H)‑one (4j)
A mixture of aromaticaldehyde (1.0 mmol) and dimedone
(1.0 mmol) with 2-aminobenzimidazole or 3-amino-1,2,4-
triazole (1.0 mmol) was stirred in acetic acid (5 mL) at 60 °C
for the appropriate time (Tables 3, 4). The progress of the
reaction was monitored by TLC. After completion of the
reaction, a thick precipitate was obtained. The solid product
was filtered off and washed with acetic acid (3 × 2 mL) to
give the pure products 4 and 6, and subsequently dried in air.
The pure products were characterized by conventional spec-
troscopic methods. Physical and spectral data for the com-
pounds, 4b, 4c, 4h, 4j, 6a, 6c, and 6h are represented below:
White solid (98 % yield); m.p. 227–229 °C; IR (KBr,
cm−1): 3415, 3143, 3093, 2959, 2931, 1642, 1579, 1455,
1369, 1264, 736; H NMR (400 MHz, CDCl3): δ 1.13 (s,
1
3H, CH3), 1.15 (s, 3H, CH3), 2.24 (d, J = 16.0 Hz, 1H,
H-5), 2.29 (d, J = 16.0 Hz, 1H, H’-5), 2.53 (d, J = 16.0 Hz,
1H, H-7), 2.60 (d, J = 16.0 Hz, 1H, H’-7), 3.81 (s, 3H,
OCH3), 3.83 (s, 3H, OCH3), 6.68 (s, 1H, H-9), 6.85 (dd,
J = 8.0, 2.0 Hz, 1H, Ar–H), 6.97 (dd, J = 8.0, 2.0 Hz, 1H,
Ar–H), 7.01 (t, J = 8.0 Hz, 1H, Ar–H), 7.64 (s, 1H, H-2),
11.71 (s, 1H, NH); 13C NMR (100 MHz, CDCl3): δ 28.0,
28.6, 32.8, 40.7, 50.5, 55.1, 55.7, 60.4, 107.0, 112.8, 121.2,
123.7, 133.4, 147.2, 147.4, 148.1, 149.3, 152.8, 193.8; MS
(EI, 70 eV) m/z (%): 354 (M+, 27), 323 (100), 296 (49),
270 (5), 239 (2), 217 (10), 185 (2), 161 (13), 138 (1), 115
(4), 84 (11), 55 (5); Anal. Calcd for C19H22N4O3: C, 64.39;
H, 6.26; N, 15.81. Found: C, 64.50; H, 6.45; N, 15.94 %.
6,7‑dihydro‑6,6‑dimethyl‑9‑p‑tolyl‑[1,2,4]triazolo[5,1‑b]
quinazolin‑8(4H,5H,9H)‑one (4b)
White solid (95 % yield), m.p. = 262–264 °C; IR (KBr,
cm−1) 3421, 3036, 2964, 1649, 1578, 1364, 1259, 757;
1 3