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MHz, DMSO-d6, ppm): d 12.52 (br s, 1H), 8.36 (d, 1H, J ¼ 16.0 Hz),
7.77 (d, 1H, J ¼ 7.8 Hz) 7.55–7.48 (m, 2H), 7.42 (s, 1H), 7.33–7.30
(m, 2H), 7.23 (s, 1H), 3.89 (s, 3H), 3.83 (s, 3H). 13C{1H} NMR (101
MHz, DMSO-d6, ppm): d 155.2, 153.4, 151.1, 149.2, 135.7, 132.8,
132.1, 130.3, 128.8, 127.9, 124.0, 123.6, 116.5, 116.1, 115.7, 109.7,
56.5, 56.3. ESI-MS: m/z 389, 391 [M + H]+. HPLC purity: 91.5% (tR ¼
(E)-3-(4-Chlorostyryl)-6-nitroquinoxalin-2(1H)-one
(4j).
Yellow solid. Yield: 79% (0.26 g). Mp 266–268 ꢀC. 1H NMR (400
MHz, DMSO-d6, ppm): d 12.86 (br s, 1H), 8.49 (s, 1H), 8.32 (d,
1H, J ¼ 9.4 Hz), 8.14–8.07 (m, 2H), 7.94 (d, 1H, J ¼ 8.7 Hz), 7.80–
7.79 (m, 1H), 7.66–7.58 (m, 1H), 7.51–7.41 (m, 2H). 13C{1H} NMR
(101 MHz, DMSO-d6, ppm): d 156.8, 154.9, 147.1, 138.7, 137.9,
136.4, 135.0, 135.0, 132.4, 130.3, 130.1, 129.9, 129.6, 122.5,
118.3, 111.2. ESI-MS: m/z 328, 330 [M + H]+. HPLC purity: 99.4%
(tR ¼ 36.1 min). HRMS (ESI-TOF) m/z: [M + H]+ calcd for
33.3 min). HRMS (ESI-TOF) m/z: [M
+
H]+ calcd for
C18H1679BrN2O3, 387.0339; found, 387.0366.
(E)-3-(2-Bromo-5-hydroxy-4-methoxystyryl)quinoxalin-2(1H)-
one (4q). Dark green solid. Yield: 84% (0.31 g). Mp 257–259 ꢀC.
1H NMR (400 MHz, DMSO-d6, ppm): d 12.50 (br s, 1H), 12.33 (s,
1H), 8.23 (d, 1H, J ¼ 15.9 Hz), 7.77 (d, 1H, J ¼ 7.8 Hz), 7.69 (d,
1H, J ¼ 8.0 Hz), 7.51–7.47 (m, 1H), 7.39–7.32 (m, 3H), 7.19 (s,
1H), 3.83 (s, 3H). 13C{1H} NMR (101 MHz, DMSO-d6, ppm):
d 155.2, 153.3, 150.5, 147.0, 135.2, 132.8, 132.1, 128.9, 127.9,
124.1, 123.5, 122.5, 116.5, 115.7, 114.7, 113.1, 56.5. ESI-MS: m/z
375, 377 [M + H]+. HPLC purity: 95.4% (tR ¼ 31.4 min). HRMS
(ESI-TOF) m/z: [M + H]+ calcd for C17H1479BrN2O3, 373.0182;
found, 373.0187.
C
16H11ClN3O3, 328.0483; found, 328.0499.
(E)-3-(4-Bromostyryl)quinoxalin-2(1H)-one (4k). Yellow solid.
Yield: 88% (0.29 g). Mp 298–299 ꢀC (298–300 ꢀC).4a 1H NMR (400
MHz, DMSO-d6, ppm): d 12.52 (br s, 1H), 8.03 (d, 1H, J ¼ 16.1
Hz), 7.79 (d, 1H, J ¼ 8.1 Hz), 7.72–7.70 (m, 2H), 7.66–7.62 (m,
3H), 7.53–7.50 (m, 1H), 7.34–7.30 (m, 2H). 13C{1H} NMR (101
MHz, DMSO-d6, ppm): d 155.3, 153.2, 136.3, 135.7, 132.8, 132.4,
132.1, 130.6, 130.1, 128.9, 124.2, 123.2, 123.0, 115.8, 79.5. ESI-
MS: m/z 329, 331 [M + H]+.
(E)-3-(4-(Dimethylamino)styryl)quinoxalin-2(1H)-one
(4l).
Orange solid. Yield: 90% (0.26 g). Mp 242–243 ꢀC (240–244 ꢀC).1d
1H NMR (400 MHz, DMSO-d6, ppm): d 12.38 (br s, 1H), 7.97 (d,
1H, J ¼ 16.0 Hz), 7.72 (d, 1H, J ¼ 4.9 Hz), 7.56 (d, 1H, J ¼ 8.6 Hz),
7.44–7.37 (m, 3H), 7.28–7.26 (m, 3H), 6.75 (d, 1H, J ¼ 8.6 Hz),
2.98 (s, 6H). 13C{1H} NMR (101 MHz, DMSO-d6, ppm): d 155.4,
153.9, 151.6, 138.3, 133.1, 131.7, 129.7, 129.3, 128.3, 124.0,
123.9, 116.5, 115.6, 112.5, 40.3. ESI-MS: m/z 292 [M + H]+.
(E)-3-(4-Nitrostyryl)quinoxalin-2(1H)-one (4m).6 Yellow solid.
Yield: 86% (0.25 g). Mp 287–289 ꢀC (288–290 ꢀC). 1H NMR (400
MHz, DMSO-d6, ppm): d 12.17 (br s, 1H), 8.11 (d, 1H, J ¼ 8.2 Hz),
8.03–7.99 (m, 3H), 7.88 (d, 1H, J ¼ 8.3 Hz), 7.68–7.64 (m, 2H),
7.56 (d, 1H, J ¼ 7.7 Hz), 7.47–7.39 (m, 2H). 13C{1H} NMR (101
MHz, DMSO-d6, ppm): d 155.2, 152.9, 147.7, 143.0, 135.0, 132.8,
132.4, 131.0, 129.1, 126.9, 124.5, 124.1, 115.9. ESI-MS: m/z 294
[M + H]+.
(E)-3-(2-(Triuoromethyl)styryl)quinoxalin-2(1H)-one
(4r).
Yellow solid. Yield: 84% (0.27 g). Mp 238–240 ꢀC. 1H NMR (400
MHz, DMSO-d6, ppm): d 12.58 (br s, 1H), 8.45 (d, 1H, J ¼ 16.2
Hz), 8.10 (d, 1H, J ¼ 7.6 Hz), 7.81–7.70 (m, 3H), 7.68–7.52 (m,
3H), 7.35–7.27 (m, 2H). 13C{1H} NMR (101 MHz, DMSO-d6,
ppm): d 155.2, 152.8, 134.9, 133.6, 132.2, 132.2, 131.0, 129.8,
1
2
129.1, 128.4 (q, JCF ¼ 275 Hz), 128.1, 127.1, 126.6 (q, JCF ¼ 5
Hz), 115.8. 19F NMR (376 MHz, DMSO-d6, ppm): d ꢂ57.62 (s).
ESI-MS: m/z 317 [M + H]+. HPLC purity: 97.4% (tR ¼ 34.9 min).
HRMS (ESI-TOF) m/z: [M + H]+ calcd for C17H12F3N2O, 317.0896;
found, 317.0905.
(E)-3-(4-(Methylthio)styryl)quinoxalin-2(1H)-one (4s). Yellow
1
ꢀ
solid. Yield: 86% (0.25 g). Mp 230–233 C. H NMR (400 MHz,
DMSO-d6, ppm): d 12.51 (br s, 1H), 8.00 (d, 1H, J ¼ 16.2 Hz), 7.76
(d, 1H, J ¼ 7.3 Hz), 7.65 (d, 1H, J ¼ 8.3 Hz), 7.56 (d, 1H, J ¼ 16.2
Hz), 7.50–7.47 (m, 1H), 7.33–7.27 (m, 5H), 2.50 (s, 3H). 13C{1H}
NMR (101 MHz, DMSO-d6, ppm): d 155.3, 153.4, 140.7, 137.1,
132.8, 132.8, 131.9, 130.2, 129.8, 128.7, 128.6, 128.3, 126.3,
124.1, 123.6, 121.2, 115.7, 14.7. ESI-MS: m/z 295 [M + H]+. HPLC
purity: 99.9% (tR ¼ 30.6 min). HRMS (ESI-TOF) m/z: [M + H]+
calcd for C17H15N2OS, 295.0900; found, 295.0905.
(E)-3-(3-Bromo-4-uorostyryl)quinoxalin-2(1H)-one (4n). Yellow
1
solid. Yield: 86% (0.30 g). Mp 236–238 ꢀC. H NMR (400 MHz,
DMSO-d6, ppm): d 12.52 (br s, 1H), 8.07–7.96 (m, 2H), 7.76–7.74 (m,
2H), 7.57 (d, 1H, J ¼ 16.1 Hz), 7.51–7.47 (m, 1H), 7.42–7.38 (m, 1H),
7.30–7.28 (m, 2H). 13C{1H} NMR (101 MHz, DMSO-d6, ppm):
d 160.2–157.8 (d, 1JCF ¼ 242 Hz), 155.2, 153.1, 134.9, 132.9–132.7 (d,
2JCF ¼ 16.6 Hz), 132.2, 130.5, 129.4–129.3 (d, 3JCF ¼ 7.6 Hz), 128.9,
124.0, 123.8, 117.8, 117.5, 115.8, 109.3, 109.1. ESI-MS: m/z 346, 348
[M + H]+. HPLC purity: 99.8% (tR ¼ 35.4 min). HRMS (ESI-TOF) m/
z: [M + H]+ calcd for C16H1181BrFN2O, 347.0013; found, 347.0025.
(E)-3-(3-Bromo-4-methoxystyryl)quinoxalin-2(1H)-one (4o).
Yellow solid. Yield: 86% (0.31 g). Mp 260–262 ꢀC. 1H NMR (400
MHz, DMSO-d6, ppm): d 12.49 (br s, 1H), 8.00–7.96 (m, 2H),
7.77–7.74 (m, 2H), 7.54–7.47 (m, 2H), 7.33–7.29 (m, 2H), 7.18 (d,
1H, J ¼ 8.6 Hz), 3.90 (s, 3H). 13C{1H} NMR (101 MHz, DMSO-d6,
ppm): d 156.7, 155.3, 153.4, 135.9, 132.8, 132.3, 132.0, 130.7,
130.2, 129.2, 128.7, 124.0, 121.4, 115.7, 113.4, 111.8, 56.9. ESI-
MS: m/z 359, 361 [M + H]+. HPLC purity: 92.5% (tR ¼ 34.2
min). HRMS (ESI-TOF) m/z: [M + H]+ calcd for C17H1479BrN2O2,
357.0233; found, 357.0250.
(E)-3-(2-(Pyridin-2-yl)vinyl)quinoxalinꢀ-2(1H)-one (4t).1f Brown
1
ꢀ
solid. Yield: 84% (0.21 g). Mp 209–211 C (208.6–210.5 C). H
NMR (400 MHz, DMSO-d6, ppm): d 12.26 (br s, 1H), 7.69 (d, 1H, J
¼ 8.0 Hz), 7.65–7.62 (m, 1H), 7.53 (d, 1H, J ¼ 7.9 Hz), 7.48–7.45
(m, 1H), 7.39–7.35 (m, 1H), 7.29–7.25 (m, 3H), 7.19–7.11 (m,
2H). 13C{1H} NMR (101 MHz, DMSO-d6, ppm): d 159.7, 155.4,
155.1, 149.3, 136.6, 132.4, 132.1, 132.0, 131.9, 129.8, 128.3,
123.5, 123.3, 115.7, 115.5. ESI-MS: m/z 250 [M + H]+.
(E)-3-(2-(Thiophen-2-yl)vinyl)quinoxalin-2(1H)-one (4u).1f Brown
solid. Yield: 88% (0.22 g). Mp 242–244 ꢀC (241.8–243.4 ꢀC). H
1
NMR (400 MHz, DMSO-d6, ppm): d 12.55 (br s, 1H), 8.23 (d, 1H, J ¼
16 Hz), 7.75 (d, 1H, J ¼ 8.0 Hz), 7.71–7.66 (m, 1H), 7.51–7.45 (m,
2H), 7.33–7.27 (m, 3H), 7.16 (1H, m). 13C{1H} NMR (101 MHz,
DMSO-d6, ppm): d 155.2, 153.1, 148.2, 142.0, 132.9, 132.0, 131.0,
130.7, 130.2, 129.1, 128.7, 124.1, 121.4, 115.8. ESI-MS: m/z 255 [M +
H]+.
(E)-3-(2-Bromo-4,5-dimethoxystyryl)quinoxalin-2(1H)-one (4p).
1
ꢀ
Yellow solid. Yield: 90% (0.35 g). Mp 262–264 C. H NMR (400
15972 | RSC Adv., 2020, 10, 15966–15975
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