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((CD3)2CO) d 2.41 (s, 3H, CH3); 7.54 (d, J = 8.1, 1H, Ar-H); 7.58 (t,
J = 7.8, 1H, Ar-H); 7.89 (t, J = 7.8, 1H, Ar-H); 8.12 (d, J = 7.7, 1H,
Ar-H); 11.30 (s, 2H, NH2); IR (KBr) [cmÀ1]: 3323; 3246; 1758;
1682; 1641; 1621; 1518; 1466; 1381; 776; purity: 92.88%; UV:
(d, J = 16.4, 1H, C@C–H); 7.39 (d, J = 6.5, 2H, Ar-H); 7.46–7.53 (m,
2H, Ar-H); 7.64 (s, 1H, Ar-H); 7.79 (d, J = 16, 1H, C@C–H); 7.77–
7.83 (m, 2H, Ar-H); 8.33 (d, J = 7.5, 1H, Ar-H); 10.64 (s, 1H, NH);
purity: 96.51%; UV: kmax = 326.4; log e = 3.59.
kmax = 314.9; log e = 3.57.
4.3.2.7. 2-((E)-2-(4-Methoxy-phenyl)-vinyl)-3H-quinazolin-4-
one (5g). Yield 33% of white solid; mp 280–281 °C (lit. mp 284–
285 °C28); 1H NMR (DMSO-d6) d 3.80 (s, 3H, OCH3); 6.84 (d,
J = 16.2, 1H, C@C–H); 7.01 (d, J = 8.4, 2H, Ar-H); 7.45 (t, J = 7.8,
1H, Ar-H); 7.60 (d, J = 8.4, 2H, Ar-H); 7.64 (d, J = 8.1, 1H, Ar-H);
7.78 (t, J = 8.0, 1H, Ar-H); 7.90 (d, J = 16.1, 1H, C@C–H); 8.08 (d,
J = 7.9, 1H, Ar-H); 12.25 (s, 1H, N–H); purity: 94.36%; UV:
4.3.1.2. 2-Methyl-6-nitro-4-oxo-4H-quinazoline-3-carboxylic
acid amide (4b). Yield 65% of yellow solid; mp 159 °C; 1H NMR
((CD3)2CO) d 2.27 (s, 3H, CH3); 8.43 (d, J = 9.4, 1H, Ar-H); 8.83 (s,
1H, Ar-H); 8.90 (d, J = 9.4, 1H, Ar-H); 11.30 (s, 2H, NH2); IR (KBr)
[cmÀ1]: 3273; 3133; 1716; 1684; 1616; 1587; 1514; 1473; 1372;
872; 857; 749; purity: 95.37%; UV: kmax = 304.9; log e = 3.51.
kmax = 322.7; log e = 3.59.
4.3.2. General method for synthesis of styryl-compounds 5a–l
A mixture of quinazolin-4-one (0.01 mol) and the appropriate
aldehyde (0.02 mol) was mixed thoroughly and irradiated in a
monomode cavity of the microwave reactor using pulse sequence
(3 Â 5 min with 30 s intervals) at 250 W. During irradiation, the
temperature was controlled between the range of 150–180 °C.
After the reaction, the mixture was cooled and washed with boiling
ether. The product was crystallized from acetic acid.
4.3.2.8. 2-((E)-2-(4-Bromo-phenyl)-vinyl)-3H-quinazolin-4-one
(5h). Yield 66% of white solid; mp 332 °C; 1H NMR (DMSO-d6) d
7.03 (d, J = 16.15, 1H, C@C–H); 7.49 (t, J = 8.35, 1H, Ar-H); 7.61
(d, J = 8.2, 1H, Ar-H); 7.64 (d, J = 8.3, 2H, Ar-H); 7.66 (d, J = 8.2,
1H, Ar-H); 7.68 (d, J = 8.2, 1H, Ar-H); 7.81 (t, J = 8.1, 1H, Ar-H);
7.91 (d, J = 16.15, 1H, C@C–H); 8.11 (d, J = 8.35, 1H, Ar-H); 12.36
(s, 1H, N–H); purity: 97.64%; UV: kmax = 326.7; log e = 3.58.
The following compounds were prepared in this manner.
4.3.2.9. 2-((E)-2-(4-Carbaldehyde-phenyl)-vinyl)-3H-quinazo-
lin-4-one (5i). Yield 35% of white solid; mp 218 °C; 1H NMR
(CDCl3) d 7.16 (d, J = 16.1, 1H, C@C–H); 7.50 (t, J = 7.3, 1H, Ar-H);
7.69 (d, J = 8.1, 2H, Ar-H); 7.82 (t, J = 8.15, 1H, Ar-H); 7.87 (d,
J = 8.15, 1H, Ar-H); 7.97 (d, J = 8.15, 1H, Ar-H); 8.00 (d, J = 16.2,
1H, C@C–H); 8.11 (d, J = 7.9, 2H, Ar-H); 9.95 (s, 1H, CHO); 10.02
4.3.2.1. 2-((E)-Styryl)-3H-quinazolin-4-one (5a). Yield 50% of
white solid; mp 253–255 °C (lit. mp 252 °C28); 1H NMR DMSO-
d6) d 7,00 (d, J = 16.23 Hz, 1H, C@C–H); 7.41 (t, J = 7.5, 1H, Ar-H);
7.42–7.49 (m, 3H, Ar-H); 7.65–7.68 (m, 3H, Ar-H); 7,80 (t, J = 7.8,
1H, Ar-H); 7.95 (d, J = 16.16 Hz, 1H, C@C–H); 8.10 (d, J = 7.57, 1H,
Ar-H); 12.35 (s, 1H, N–H); purity: 97.95%; UV: kmax = 321.3;
(s, 1H, N–H); purity: 96.93%; UV: kmax = 337.9; log e = 3.69.
log e = 3.53.
4.3.2.10. 2-((E)-2-(2,4-Dimethoxy-phenyl)-vinyl)-3H-quinazo-
lin-4-one (5j). Yield 57% of white solid; mp 228–230 °C (lit. mp
228–230 °C28); 1H NMR (DMSO-d6) d 3.82 (s, 3H, OCH3); 3.90 (s,
3H, OCH3); 6.63 (d, J = 8.5, 1H, Ar-H); 6.64 (s, 1H, Ar-H); 6.94 (d,
J = 16.15, 1H, C@C-H); 7.43 (t, J = 7.7, 1H, Ar-H); 7.53 (d, J=8.4,
1H, Ar-H); 7.64 (d, J = 8.2, 1H, Ar-H); 7.77 (t, J = 8.1, 1H, Ar-H);
8.07 (d, J = 15.2, 1H, C@C–H); 8.08 (d, J = 8.4, 1H, Ar-H); 12.26 (s,
4.3.2.2. 2-((E)-2-(2-Methoxy-phenyl)-vinyl)-3H-quinazolin-4-
one (5b). Yield 76% of white solid; mp 234–236 °C (lit. mp 234–
236 °C28); 1H NMR (DMSO-d6) d 3.90 (s, 3H, OCH3); 7.02 (t,
J = 7.45 1H, Ar-H); 7.07 (d, J = 16.25, 1H, C@C–H); 7.11 (d, J = 7.0,
1H, Ar-H); 7.39 (t, J = 7.4, 1H, Ar-H); 7.45 (t, J = 7.6, 1H, Ar-H);
7.60 (d, J = 7.69, 1H, Ar-H); 7.67 (d, J = 7.5, 1H, Ar-H); 7.79 (t,
J = 7.75, 1H, Ar-H); 8.09 (d, J = 7.65, 1H, Ar-H); 8.15 (d, J = 16.2,
1H, C@C–H); 12.36 (s, 1H, N–H); purity: 94.04%; UV: kmax = 343.4;
1H, N–H); purity: 96.27%; UV: kmax = 350.1; log e = 3.67.
log
e
= 3.62.
4.3.2.11. 2-((E)-2-(2,3,4-Trihydroxy-phenyl)-vinyl)-3H-quinazo-
lin-4-one (5k). Yield 60% of brown solid; mp 300 °C (decomp.);
1H NMR (DMSO-d6) d 6.39 (d, J = 8.5, 1H, Ar-H); 6.83 (d, J = 16.0,
1H, C@C–H); 6.88 (d, J = 8.5, 1H, Ar-H); 7.40 (t, J = 8.1, 1H, Ar-H);
7.63 (d, J = 8.1, 1H, Ar-H); 7.75 (t, J = 8.1, 1H, Ar-H); 8.05 (d,
J = 7.9, 1H, Ar-H); 8.10 (d, J = 16.05, 1H, C@C–H); 8.57 (s, 1H,
OH); 9.07 (s, 1H, OH); 9.68 (s, 1H, OH); 12.19 (s, 1H, NH); purity:
4.3.2.3. 2-((E)-2-(2-Bromo-phenyl)-vinyl)-3H-quinazolin-4-one
(5c). Yield 71% of white solid; mp 279 °C; 1H NMR (CDCl3) d 6.93
(d, J = 16.45, 1H, C@C–H); 7.40 (t, J = 7.6, 1H, Ar-H); 7.50 (t, J = 7.6,
1H, Ar-H); 7.67 (d, J = 7.9, 1H, Ar-H); 7.74–7.82 (m, 4H, Ar-H); 8.12
(d, J = 16.45, 1H, C@C–H); 8.36 (d, J = 7.8, 1H, Ar-H); 10.96 (s, 1H,
NH); purity: 98.84%; UV: kmax = 326.9; log
e
= 3.59.
97.67%; UV: kmax = 365.0; log e = 3.65.
4.3.2.4. 2-((E)-2-(3-Methoxy-phenyl)-vinyl)-3H-quinazolin-4-
one (5d). Yield 68% of white solid; mp 239–241 °C; 1H NMR
(DMSO-d6) d 3.81 (s, 3H, OCH3); 6.98 (d, J = 8.1, 1H, Ar-H); 7.01
(d, J = 16.8, 1H, C@C–H); 7.22 (s, 1H, Ar-H); 7.23 (d, J = 7.6, 1H,
Ar-H); 7.37 (t, J = 7.4, 1H, Ar-H); 7.47 (t, J = 7.55, 1H, Ar-H); 7.66
(d, J = 7.5, 1H, Ar-H); 7.80 (t, J = 7.9, 1H, Ar-H); 7.91 (d, J = 16.1,
1H, C@C–H); 8.10 (d, J = 8.2, 1H, Ar-H); 12.31 (s, 1H, NH); purity:
4.3.2.12. 2-((E)-2-(4-Bromo-phenyl)-vinyl)-6-nitro-3H-quinazo-
lin-4-one (5l). Yield 32% of brown solid; mp 320 °C (decomp.); 1H
NMR (DMSO-d6) d 7.07 (d, J = 16.1, 1H, C@C–H); 7.65 (d, J = 8.5, 2H,
Ar-H); 7.69 (d, J = 8.5, 2H, Ar-H); 7.84 (d, J = 7.9, 1H, Ar-H); 8.04 (d,
J = 16.1, 1H, C@C–H); 8.54 (d, J = 7.0, 1H, Ar-H); 8.80 (s, 1H, Ar-H);
12.81 (s, 1H, N–H); purity: 96.63%; UV: kmax = 339.9; log e = 3.67.
96.82%; UV: kmax = 326.4; log
e
= 3.58.
4.3.3. General method for synthesis of compounds 6a–e
A mixture of compound 5a (or 5b, 5d, 5g, 5j) (0.01 mol), N,N-
dimethylaniline (0.02 mol) and phosphorus oxychloride
(0.015 mol) in dry benzene (50 mL) was stirred and heated under
reflux for 3 h. The reaction mixture was then cooled and filtered.
The filtrate was diluted with benzene (30 mL) and the solution
washed with water (50 mL), twice with 20% aqueous NaOH
(50 mL) and finally twice with water. After drying with MgSO4,
the organic solvent was evaporated and the product obtained
was crystallized from heptane.
4.3.2.5. 2-((E)-2-(3-Bromo-phenyl)-vinyl)-3H-quinazolin-4-one
(5e). Yield 43% of white solid; mp 277–279 °C; 1H NMR (CDCl3) d
6.91 (d, J = 16.3, 1H, C@C–H); 7.33 (t, J = 7.5, 1H, Ar-H); 7.50–7.56
(m, 2H, Ar-H); 7.55 (s, 1H, Ar-H); 7.73 (d, J = 16.4, 1H, C@C–H);
7.76–7.82 (m, 3H, Ar-H); 8.33 (d, J = 7.9, 1H, Ar-H); 10.31 (s, 1H,
NH); purity: 97.34%; UV: kmax = 326.4; log e = 3.58.
4.3.2.6. 2-((E)-2-(3-Chloro-phenyl)-vinyl)-3H-quinazolin-4-one
(5f). Yield 93% of white solid; mp 289 °C; 1H NMR (CDCl3) d 6.93
The following compounds were prepared in this manner.