W. Wimonsong and S. Yotphan
Tetrahedron 81 (2021) 131919
4
.3. Typical experimental procedure for the PIDA-promoted direct
NMR (CDCl
3
, 400 MHz):
d
9.82 (s, 1H), 8.22 (s, 1H), 8.08 (dd, J ¼ 8.1,
CeN bond cross coupling of quinoxalinones and azoles: synthesis of
compounds 3ae3t
1.3 Hz, 1H), 7.66e7.61 (m, 1H), 7.48e7.39 (m, 2H), 6.04e5.94 (m,
1H), 5.27 (d, J ¼ 10.4 Hz,1H), 5.16 (d, J ¼ 17.2 Hz,1H), 5.06 (dt, J ¼ 5.1,
13
3
1.5 Hz, 2H) ppm; C NMR (CDCl , 100 MHz): d 152.7, 150.0, 146.8,
An 8 mL oven-dried scintillation vial equipped with a magnetic
stir bar was charged with a mixture of 2-quinoxalinone (0.50 mmol,
141.2, 132.0, 131.4, 131.2, 130.9, 129.8, 125.2, 119.0, 114.6, 45.6 ppm;
þ
HRMS (ESI): m/z [MþNa] calcd for C13
11 5
H N ONa: 276.0856; found:
1.0 equiv), triazole (0.75 mmol, 1.5 equiv), PIDA (0.75 mmol, 1.5
276.0854.
equiv), and DCE (CH
reaction mixture was stirred at 60 C for 16e24 h. Upon comple-
2
ClCH
2
Cl) (2 mL). The vial was capped, and the
ꢀ
4
.3.6. Methyl-2-(2-oxo-3-(1H-1,2,4-triazol-1-yl)quinoxalin-1(2H)-
2
tion, distilled deionized H O (10 mL) was added, and the mixture
yl)acetate (3f)
was extracted with ethyl acetate (3 ꢁ 25 mL). The combined
Purification by column chromatography (Hexanes/EtOAc,1/1) as
organic layer was washed with saturated NaCl, dried over anhy-
ꢀ
a white solid (119 mg, 84% yield); mp ¼ 193.2e195.0 C; IR (KBr):
drous Na
2
SO
4
, and concentrated in vacuo. The crude product was
ꢂ1 1
3152, 3114, 1732, 1657, 1606, 1272, 1235, 1132, 980, 756 cm
; H
2
purified by SiO column chromatography to afford the desired
products.
(CDCl
3
, 400 MHz):
d
9.74 (s, 1H), 8.21 (s, 1H), 8.08 (dd, J ¼ 8.1, 1.1 Hz,
1
5
H), 7.65e7.61 (m, 1H), 7.47 (t, J ¼ 7.7 Hz,1H), 7.19 (d, J ¼ 8.4 Hz,1H),
13
3
.17 (s, 2H), 3.81 (s, 3H) ppm; C NMR (CDCl , 100 MHz): d 166.9,
4.3.1. 1-Ethyl-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-one (3a)
152.9, 150.1, 146.8, 141.0, 131.9, 131.7, 131.1, 131.0, 125.5, 113.4, 53.3,
Purification by column chromatography (Hexanes/EtOAc, 1/1) as
þ
4
3
4.3 ppm; HRMS (ESI): m/z [MþNa] calcd for C13
11 5 3
H N O Na,
ꢀ
a white solid (102 mg, 84% yield); mp ¼ 170.3e171.4 C; IR (KBr):
08.0754; found: 308.0753.
3
149, 3102, 1660, 1605, 1593, 1506, 1398, 1303, 1273, 1200, 1122,
ꢂ1
1
764 cm
;
H NMR (400 MHz, CDCl
3
): d 9.83 (s, 1H), 8.22 (s, 1H),
4
.3.7. 1-Phenyl-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-one (3g)
8
.08 (d, J ¼ 7.9 Hz, 1H), 7.69e7.65 (m, 1H), 7.48e7.44 (m, 2H), 4.48
13
Purification by column chromatography (Hexanes/EtOAc,1/1) as
(
q, J ¼ 7.2 Hz, 2H), 1.47 (t, J ¼ 7.2 Hz, 3H) ppm; C NMR (100 MHz,
ꢀ
ꢂ1
a pale yellow solid (94 mg, 65% yield); mp ¼ 250.8e251.5 C; IR
3
CDCl ): d 152.6, 149.7, 146.7, 141.1, 131.6, 131.3, 131.2.130.9, 124.9,
1
13.8, 38.6, 12.4 ppm; HRMS (ESI): m/z [MþH]þ calcd for
(Neat): 3165, 3098, 1672, 1604, 1386, 1202, 1122, 965, 756 cm ; H
CDCl , 400 MHz): 9.77 (s, 1H), 8.22 (s, 1H), 8.12e8.10 (m, 1H),
.70e7.61 (m, 3H), 7.47e7.42 (m, 2H), 7.36 (d, J ¼ 7.3 Hz, 2H),
1
(
7
6
3
d
12 12 5
C H N O: 242.1036; found: 242.1034.
13
.78e6.76 (m, 1H) ppm; C NMR (CDCl
3
, 100 MHz): d 152.9, 150.3,
4
.3.2. 1-Methyl-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-one
3b) [17]
Purification by column chromatography (Hexanes/EtOAc, 1/1) as
a pale yellow solid (76 mg, 67% yield); IR (KBr): 3150, 3104, 1658,
146.9,141.6,135.2,133.6,131.1,131.0,130.8,130.3,130.2,128.0,125.3,
(
þ
1
15.8 ppm; HRMS (ESI): m/z [MþNa] calcd for C16
11 5
H N ONa,
312.0856; found: 312.0858.
ꢂ1
1
1602, 1508, 1203, 1130, 990 952, 774, 671 cm
;
H NMR (CDCl
3
/
MeOD, 400 MHz):
d
9.78 (s, 1H), 8.17 (s, 1H), 8.01 (dd, J ¼ 8.0, 1.2 Hz,
4
.3.8. 3-(1H-1,2,4-Triazol-1-yl)quinoxalin-2(1H)-one (3h)
13
1
H), 7.66e7.61 (m, 1H), 7.45e7.39 (m, 2H), 3.83 (s, 3H) ppm;
C
Purification by column chromatography (pure EtOAc) as a yel-
NMR (CDCl /MeOD, 100 MHz): 152.4, 150.2, 146.7, 140.9, 132.7,
3
d
ꢀ
low solid (105 mg, 99% yield); mp ¼ 189.2e190.1 C; IR (KBr): 3160,
1
31.5, 130.9, 130.6, 125.2, 114.0, 30.1 ppm; HRMS (ESI): m/z
ꢂ1 1
3
103, 1686, 1614, 1508, 1396, 1272, 1199, 1130, 981, 752 cm
NMR (DMSO-d , 400 MHz): 13.10 (s, 1H), 9.58 (s, 1H), 8.33 (s, 1H),
.83 (dd, J ¼ 8.0, 0.8 Hz, 1H), 7.63e7.59 (m, 1H), 7.42e7.38 (m, 2H)
; H
þ
[MþNa] calcd for C11
9 5
H N ONa: 250.0699; found: 250.0698.
6
d
7
4.3.3. 1-Pentyl-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-one (3c)
13
6
ppm; C NMR (DMSO-d , 100 MHz): d 152.1, 150.7, 146.5, 142.7,
Purification by column chromatography (Hexanes/EtOAc, 1/1) as
1
[
31.8, 130.8, 130.1, 128.5, 124.2, 115.5 ppm; HRMS (ESI): m/z
ꢀ
MþNa]þ calcd for C10
a yellow solid (123 mg, 87% yield); mp ¼ 119.0e120.7 C; IR (KBr):
7 5
H N ONa: 236.0543; found: 236.0544.
ꢂ1
1
3150, 1659, 1606, 1589, 1476, 1389, 1206, 1129, 982, 754 cm
; H
NMR (CDCl , 400 MHz):
3
d
9.82 (s, 1H), 8.21 (s, 1H), 8.07 (dd, J ¼ 8.1,
4
.3.9. 6-Chloro-1-ethyl-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-
1
2
.2 Hz, 1H), 7.67e7.63 (m, 1H), 7.47e7.41 (m, 2H), 4.38 (t, J ¼ 7.9 Hz,
one (3i)
H), 1.87e1.79 (m, 2H), 1.52e1.38 (m, 4H), 0.94 (t, J ¼ 7.0 Hz, 3H)
1
3
Purification by column chromatography (Hexanes/EtOAc,1/1) as
ppm; C NMR (CDCl
3
, 100 MHz): d 152.7, 150.0, 146.8, 141.1, 131.9,
ꢀ
a yellow solid (100 mg, 73% yield); mp ¼ 274.9e276.1 C; IR (KBr):
131.3, 131.2, 130.9, 124.9, 114.0, 43.5, 29.1, 27.1, 22.4, 14.0 ppm;
ꢂ1
1
þ
3165, 3120, 1670, 1602, 1481, 1440, 1384, 1197, 1121, 976 cm
;
H
HRMS (ESI): m/z [MþNa] calcd for C15
17 5
H N ONa: 306.1325; found:
NMR (CDCl
3
, 400 MHz): d 9.82 (s, 1H), 8.21 (s, 1H), 8.07 (d,
3
06.1328.
J ¼ 2.3 Hz, 1H), 7.61 (dd, J ¼ 9.1, 2.2 Hz, 1H), 7.38 (d, J ¼ 9.0 Hz, 1H),
13
4
1
.45 (q, J ¼ 7.2 Hz, 2H), 1.47 (t, J ¼ 7.2 Hz, 3H) ppm; C NMR (CDCl
00 MHz): 153.0, 149.6, 147.0, 142.1, 132.0, 131.5, 130.4, 130.3,
130.2, 115.0, 39.0, 12.6 ppm; HRMS (ESI): m/z [MþH] calcd for
11ClN O: 276.0647; found: 276.0648.
3
,
4.3.4. 1-Benzyl-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-one (3d)
d
Purification by column chromatography (Hexanes/EtOAc, 1/1) as
þ
ꢀ
ꢂ1
a yellow solid (128 mg, 84% yield); mp ¼ 163.3e164.9 C; IR (KBr):
1
C
12
H
5
3159, 3118, 1661, 1604, 1392, 1205, 1128, 986, 759 cm
;
H NMR
(
1
CDCl
3
, 400 MHz):
d
9.84 (s,1H), 8.22 (s,1H), 8.07 (dd, J ¼ 8.0,1.2 Hz,
13
H), 7.57e7.52 (m, 1H), 7.44e7.26 (m, 7H), 5.64 (s, 2H) ppm;
C
4.3.10. 1-Ethyl-6-nitro-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-
one (3j)
NMR (CDCl
3
, 100 MHz): d 152.7, 150.4, 146.8, 141.2, 134.3, 132.1,
1
31.3, 131.2, 130.7, 129.2, 128.1, 126.8, 125.1, 114.7, 46.9 ppm; HRMS
Purification by column chromatography (Hexanes/EtOAc,1/1) as
þ
ꢀ
(
ESI): m/z [MþNa] calcd for C17
H
13
N
5
ONa: 326.1012; found:
a yellow solid (82 mg, 57% yield); mp ¼ 233.3e234.1 C; IR (KBr):
ꢂ1
1
3
26.1018.
3181, 3121, 1670, 1596, 1510, 1526, 1351, 1200, 1124 cm ; H NMR
(
CDCl
J ¼ 7.2 Hz, 2H), 1.53 (t, J ¼ 7.2 Hz, 3H) ppm; C NMR (CDCl
100 MHz): 153.5,149.5,148.5,147.5,143.4,135.1,132.0,131.9,119.5,
109.8, 39.4, 12.7 ppm; HRMS (ESI): m/z [MþH] calcd for
12 10 6 3
C H N O Na: 309.0707; found: 309.0709.
3
, 400 MHz): d 9.89 (s, 1H), 8.34e8.22 (m, 4H), 4.54 (q,
13
4.3.5. 1-Allyl-3-(1H-1,2,4-triazol-1-yl)quinoxalin-2(1H)-one (3e)
3
,
Purification by column chromatography (Hexanes/EtOAc, 1/1) as
d
ꢀ
þ
a pale yellow solid (112 mg, 88% yield); mp ¼ 151.4e152.6 C; IR
ꢂ1
1
(
KBr): 3168, 3107, 1164, 1605, 1476, 1393, 1195, 983, 758 cm ; H
5