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resulting solid was ltered, dried and recrystallized from m.p. 244–245 ꢁC (Ethanol). IR (KBr, cmꢂ1): 3431 (NH); 1632
ethanol.
(C]N); 1592 (C]C); 1541 (dNH); 830 (C–Cl). 1H-NMR (500
4.1.2.1. 4-Benzyl-1-(2-chlorophenyl)-1,2,4-triazolo[4,3-a]qui- MHz, DMSO-d6, d ppm): 4.49 (s, 2H, CH2–C6H5), 5.58 (s, 2H,
noxaline (9a). Reddish-orange crystals (0.7 g, 94.5%), m.p. triazinoquinox. C1–H2), 7.29–7.40 (m, 5H, CH2–C6H5), 7.67–
200–201 C; reported m.p. 194–195 ꢁC.22 IR (KBr, cmꢂ1): 1643 7.86 (m, 2H, triazinoquinox. C8,9–H), 7.72 (d, 2H, J ¼ 8.9 Hz,
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(C]N); 1597, 1489 (C]C); 767 (C–Cl). 1H-NMR (500 MHz, chlorophenyl C2,6–H), 8.05 (dd, 1H, J ¼ 8.25, 7.8 Hz tri-
DMSO-d6, d ppm): 4.61, 4.70 (2d, each 1H, J ¼ 14.1 Hz, CH2– azinoquinox. C7–H), 8.19 (d, 2H, J ¼ 8.9 Hz, chlorophenyl C3,5
–
C6H5), 7.10 (d, 1H, J ¼ 7.5 Hz, C6H5–C2–H), 7.26 (d, 1H, J ¼ 7.5 H), 8.34 (d, 1H, J ¼ 8.4 Hz, triazinoquinox. C10–H). 13C-NMR
Hz, C6H5–C6–H), 7.34 (t, 2H, J ¼ 7.5 Hz, C6H5–C3,5–H), 7.49– (500 MHz, DMSO-d6, d ppm): 38.9 (CH2–C6H5), 62.3 (tri-
7.55 (m, 3H, C6H5–C4–H and chlorophenyl C4,5–H), 7.62–7.71 azinoquinox. C1), 114.2 (triazinoquinox. C10), 117.8 (tri-
(m, 2H, triazoloquinox. C7,8–H), 7.78–7.86 (m, 3H, chlor- azinoquinox. C8), 122.9 (triazinoquinox. C7), 125.2 (phenyl C4),
ophenyl C3,6–H and triazoloquinox. C6–H), 8.09 (dd, 1H, J ¼ 127.1 (chlorophenyl C4), 127.8 (phenyl C3,5), 128.5 (chlor-
8.1, 1.5 Hz triazoloquinox. C9–H). 13C-NMR (500 MHz, DMSO- ophenyl C3,5), 129.0 (phenyl C2,6), 129.3 (chlorophenyl C2,6),
d6, d ppm): 42.3 (CH2–C6H5), 73.2 (triazoloquinox. C1), 114.6 130.4, 132.5, 134.8, 136.2, 137.1, 138.2, 138.9, 147.0, 164.5,
(triazoloquinox. C9), 115 (triazoloquinox. C7), 125 (tri- 172.5, 177.5. Anal. calcd for C23H17ClN4 (384.87): C, 71.78; H,
azoloquinox. C6), 126.7 (benz. C1), 128.0, 128.1, 129.0, 129.1, 4.45; N, 14.56. Found: C, 72.06; H, 4.32; N, 14.68.
129.7, 129.9, 130.1, 132.4, 133.2, 133.8, 135.7, 136.5, 153.6,
4.1.3.3. 5-Benzyl-2-(4-bromophenyl)-1H-[1,2,4]triazino[4,3-a]
209.6. Anal. calcd for C22H15ClN4 (370.84): C, 71.25; H, 4.08; quinoxaline (10c). Yellowish crystals (0.58 g, 67.6%), m.p. 248–
N, 15.11. Found: C, 71.42; H, 4.04; N, 14.86.
249 ꢁC (Ethanol). IR (KBr, cmꢂ1): 3430 (NH); 1631 (C]N); 1587
4.1.2.2. 4-Benzyl-1-(4-nitrophenyl)-1,2,4-triazolo[4,3-a]qui- (C]C); 1539 (dNH); 762 (C–Br). 1H-NMR (500 MHz, DMSO-d6,
noxaline (9b). Brownish clusters of needles (0.7 g, 91.9%), d ppm): 4.49 (s, 2H, CH2–C6H5), 5.57 (s, 2H, triazinoquinox.
m.p. 212–213 C. IR (KBr, cmꢂ1): 1630 (sh C]N); 1601 (C] C1–H2), 7.31–7.42 (m, 5H, CH2–C6H5), 7.77–8.05 (m, 2H, tri-
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C); 1527, 1348 (NO2). H-NMR (500 MHz, DMSO-d6, d ppm): azinoquinox. C8,9–H), 7.86 (d, 2H, J ¼ 8.3 Hz, bromophenyl
4.64 (s, 2H, CH2–C6H5), 7.23 (t, 1H, J ¼ 7.65 Hz, C6H5–C4–H),
C2,6–H), 8.08–8.14 (m, 1H, triazinoquinox. C7–H), 8.10 (d, 2H, J
7.33 (t, 2H, J ¼ 7.65 Hz, C6H5–C3,5–H), 7.36 (d, 1H, J ¼ 7.65 ¼ 8.3 Hz, bromophenyl C3,5–H), 8.33 (d, 1H, J ¼ 8.4 Hz, tri-
Hz, C6H5–C2–H), 7.47 (d, 1H, J ¼ 7.65 Hz, C6H5–C6–H), 7.51– azinoquinox. C10–H). Anal. calcd for C23H17BrN4 (429.32): C,
7.60 (m, 2H, triazoloquinox. C7,8–H), 7.64 (dd, 1H, J ¼ 7.8, 64.35; H, 3.99; N, 13.05. Found: C, 64.17; H, 3.72; N, 13.26.
1.2 Hz, triazoloquinox. C6–H), 8.1 (dd, 1H, J ¼ 8.6, 1.5 Hz
4.1.4. Ethyl 3-[(3-benzylquinoxalin-2-yl)hydrazono]butyrate
triazoloquinox. C9–H), 8.12 (d, 2H, J ¼ 8.7 Hz, nitrophenyl (11). A mixture of 6 (0.5 g, 2 mmol) and ethyl acetoacetate (0.29
ꢁ
C
2,6–H), 8.51 (d, 2H, J ¼ 8.7 Hz, nitrophenyl C3,5–H). Mass g, 2.2 mmol) was heated for 1 h in an oil bath at 160–170 C,
spectrum m/z (%): 381 (M+c) (100), 380 (98), 334 (25), 233 triturated with petroleum ether (60–80 ꢁC), ltered dried and
(61), 232 (95), 205 (25), 102 (35), 91(87), 77 (25), 65 (45). Anal. recrystallized from ethanol/water. This compound was obtained
calcd for C22H15N5O2 (381.39): C, 69.28; H, 3.96; N, 8.39. as white crystals (0.5 g, 69.1%), m.p. 115–116 ꢁC. IR (KBr, cmꢂ1):
Found: C, 68.99; H, 4.09; N, 8.21.
1720 (C]O ester); 1630 (C]N); 1599, 1510 (C]C); 1287, 1193,
4.1.3. General procedure for the synthesis of 2-aryl-5- 1090 (C–O–C). 1H-NMR (500 MHz, DMSO-d6, d ppm): 1.43 (t, 3H,
benzyl-1H-[1,2,4]triazino[4,3-a]quinoxalines (10a–c). To a solu- J ¼ 6.6 Hz, CH2CH3), 2.50 (s, 3H, N]C–CH3), 3.34 (s, 2H, CH2),
tion of 6 (0.5 g, 2 mmol) in dry dioxane (10 mL), the appropriate 4.57 (q, 2H, J ¼ 6.6 Hz, CH2CH3), 4.65 (s, 2H, CH2–C6H5), 7.22 (t,
phenacyl bromide (2 mmol) was added. The reaction mixture 1H, J ¼ 7.4 Hz, C6H5–C4–H), 7.30 (t, 2H, J ¼ 7.4 Hz, C6H5–C3,5
–
was heated under reux; while a reddish precipitate separated H), 7.47 (d, 2H, J ¼ 7.4 Hz, C6H5–C2,6–H), 7.74–7.78 (m, 2H,
out during the rst 5 minutes. The reux was continued for 1 h, quinox. C6,7–H), 8.09 (ddd, 1H, J ¼ 7.4, 3.8, 2.1 Hz, quinox. C8–
the reaction mixture was cooled, and the product was ltered, H), 8.75 (ddd, 1H, J ¼ 7.5, 3.8, 2.1 Hz quinox. C5–H). 13C-NMR
dried, and recrystallized from the proper solvent.
(500 MHz,
d
ppm): 13.80 (2
ꢃ
CH3), 40 (CH2–C6H5),
4.1.3.1. 5-Benzyl-2-phenyl-1H-[1,2,4]triazino[4,3-a]quinoxa- 63.11(COOCH2CH3), 118.9 (quinox-C6), 124.85 (quinox-C8),
line (10a). Yellow clusters of needles (0.51 g, 72.9%), m.p. 126.69 (phenyl-C4), 128.43 (phenyl-C3,5), 128.59 (quinox-C5),
239–241 C (ethanol/water). IR (KBr, cmꢂ1): 3430 (NH); 1635 129.03 (quinox-C7), 129.21 (phenyl-C2,6), 129.61 (phenyl-C1),
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(C]N); 1592 (C]C); 1546 (dNH). H-NMR (500 MHz, DMSO- 136.3 (quinox-C8a), 136.59 (quinox-C4a), 142.52 (quinox-C3),
d6, d ppm): 4.49 (s, 2H, CH2–C6H5), 5.60 (s, 2H, tri- 144.53 (quinox-C2), 153.23 (N]C), 158.61(COOCH2CH3). Anal.
azinoquinox. C1–H2), 7.27–7.08 (m, 10H, Ar–H), 8.02–8.08 (m, calcd for C21H22N4O2 (362.17): C, 69.59; H, 6.12; N, 15.46.
2H, triazinoquinox. C8,9–H), 8.17 (dd, 1H, J ¼ 7.8, 2 Hz, tri- Found: C, 69.28; H, 6.20; N, 15.29.
azinoquinox. C7–H), 8.35 (d, 1H, J ¼ 6.3 Hz, triazinoquinox.
4.1.5. 2-[5-Amino-3-(4-chlorophenyl)pyrazol-1-yl]-3-benzyl-
C
10–H). Mass spectrum m/z (%): 351 (12), 350 (M+c) (50), 349 quinoxaline (13). To a solution of 6 (0.5 g, 2 mmol) in ethanol
(24), 247 (86), 246 (72), 219 (79), 218 (32), 116 (18), 103 (67), (8 mL) and acetic acid (2 mL), 4-chlorophenyl-u-cyanoaceto-
102 (28), 91 (68), 77 (100), 65 (34), 51 (43). Anal. calcd for phenone (2 mmol) was added. The reaction mixture was heated
C
23H18N4 (350.42): C, 78.83; H, 5.18; N, 15.99. Found: C, under reux for 2 h, cooled, and the separated product was
78.67; H, 4.96; N, 16.15.
ltered, dried, and recrystallized from acetonitrile as white-
4.1.3.2. 5-Benzyl-2-(4-chlorophenyl)-1H-[1,2,4]triazino[4,3-a] greyish crystals (0.8 g, 97.2%), m.p. 174–175 ꢁC. IR (KBr, cmꢂ1):
quinoxaline (10b). Orange-yellow ne needles (0.49 g, 63.7%), 3462, 3368 (NH2); 1609, 1578, 1559 (C]N, C]C); 761 (C–Cl).
Med. Chem. Commun.
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