8
6 Jyothi et al.
Asian J. Chem.
+
Spectral data
N-Phenylimidazo[1,2-a]pyrazine-2-carboxamide (7a):
Pale brown solid. IR (KBr, νmax, cm ): 3407, 3048, 2974, 2784,
10.66 (brs, 1H, NH); LC-MS: m/z 272.0[M] .Anal. calcd. (%)
OCl: C, 57.26, H, 3.33; N, 20.55. Found (%): C,
57.37, H, 3.32; N, 20.57.
for C13
H N
9 4
-1
N-(4-Bromophenyl)imidazo[1,2-a]pyrazine-2-carbo-
xamide (7f): Pale brown solid. IR (KBr, νmax, cm ): 3428,
1
9
7
642, 1596, 1555, 1515, 1461, 1386, 1344, 1233, 1199, 1088,
-1
1
67; H NMR (400 MHz, DMSO-d
.34 (t, 2H, Ar-H), 7.90 (d, 2H, Ar-H), 7.99 (s, 1H, C
-H and C -H of pyrazine), 9.19 (s,
H, imidazole ring proton), 10.47 (brs, 1H, NH); LC-MS: m/z
6
): δ 7.09 (t, 1H, Ar-H),
1
3
267, 3180, 3072, 1604, 1525, 1477, 1412, 1130, 920; H
NMR (400 MHz, DMSO-d ): δ 7.80-7.89 (m, 2H, 2H, C -H,
-H of pyrazine), 7.91-7.64 (d, 2H, Ar-H), 8.05-8.13 (d, 2H,
Ar-H), 8.40 (m, 2H, C -H of pyrazine, imidazole ring proton),
0.12 (brs, 1H, NH); LC-MS: m/z 316.0[M] .Anal. calcd. (%)
OBr: C, 49.23, H, 2.86; N, 17.67. Found (%): C,
5
-H of
6
6
pyrazine), 8.66 (s, 2H, C
1
2
3
6
C
3
+
5
39.0 [M+H] . Anal. calcd. (%) for C13
H
10
N
4
OF : C, 65.54,
3
+
1
H, 4.23; N, 23.52. Found (%): C, 65.67, H, 4.22; N, 23.54.
for C13
H N
9 4
N-(3-Chlorophenyl)imidazo[1,2-a]pyrazine-2-carbo-
-1
49.33, H, 2.88; N, 17.80.
xamide (7b): Pale brown solid. IR (KBr, νmax, cm ): 3454,
1
N-(4-Iodophenyl)imidazo[1,2-a]pyrazine-2-carbo-
xamide (7g): Pale brown solid. IR (KBr, νmax, cm ): 3362,
269, 3188, 1613, 1600, 1570, 1534, 1509, 1476, 1447, 1417,
2
851, 1640, 1469, 1409, 1358, 1194, 1139; H NMR (400 MHz,
DMSO-d ): δ 7.22 (t, 1H, Ar-H), 7.41 (d, 1H, Ar-H), 7.56 (d,
H, Ar-H), 8.02 (s, 1H, Ar-H), 8.25 (d, 1H, C -H of pyrazine),
.64 (d, 1H, C -H of pyrazine), 8.72 (s, 1H, C -H of pyrazine),
.24 (s, 1H, imidazole ring proton), 10.01 (brs, 1H, NH); LC-
-1
6
3
1
7
1
8
9
5
1
346, 1127, 921; H NMR (400 MHz, DMSO-d
.60 (m, 4H,Ar-H), 7.62-7.69 (m, 2H, C -H, C -H of pyrazine),
-H of pyrazine), 9.06 (s, 1H, imidazole ring
6
): δ 7.45-
6
3
6
3
+
7.92 (s, 1H, C
proton), 9.42 (brs, 1H, NH); LC-MS: m/z 365.28 [M+H] .Anal.
calcd. (%) for C13 OI: C, 42.88, H, 2.49; N, 15.39. Found
5
MS: m/z 272.0 [M] .Anal. calcd. (%) for C13
H
9
N OCl: C, 57.26,
4
+
H, 3.33; N, 20.55. Found (%): C, 57.35, H, 3.34; N, 20.58.
H N
9 4
N-(3-Bromophenyl)imidazo[1,2-a]pyrazine-2-carbo-
-1
(%): C, 42.99, H, 2.47; N, 15.41.
xamide (7c): Pale brown solid. IR (KBr, νmax, cm ): 3420,
N-(Pyridin-2-yl)imidazo[1,2-a]pyrazine-2-carbo-
xamide (7h): Pale brown solid. IR (KBr, νmax, cm ): 3228,
2
1
953, 2811, 2763, 1630, 1597, 1507, 1479, 1447, 1412, 1351,
-1
1
296, 991; H NMR (400 MHz, DMSO-d ): δ 7.20 (t, 1H, Ar-
6
1
2
930, 1638, 1592, 1401, 1232, 1161, 1084; H NMR (400
MHz, DMSO-d ): δ 7.19 (t, 1H, pyridine-H), 7.88 (t, 1H,
pyridine-H), 8.01 (d, 1H, pyridine-H), 8.20 (d, 1H, pyridine-
H), 8.38 (s, 1H, C -H of pyrazine), 8.64 (s, 1H, C -H of pyrazine),
.75 (s, 1H, C -H of pyrazine), 9.22 (s, 1H, imidazole ring
proton), 9.92 (brs, 1H, NH); LC-MS: m/z 240.11 [M+H] .Anal.
calcd. (%) for C12 O: C, 60.25, H, 3.79; N, 29.27. Found
H), 7.40 (d, 1H, Ar-H), 7.54 (d, 1H, Ar-H), 8.04 (s, 1H,Ar-H),
6
5 6
8.23 (d, 1H, C -H of pyrazine), 8.62 (d, 1H, C -H of pyrazine),
8
.70 (s, 1H, C
3
-H of pyrazine), 9.18 (s, 1H, imidazole ring
+
5
3
proton), 9.88 (brs, 1H, NH); LC-MS: m/z 316.0[M] . Anal.
calcd. (%) for C13 OBr: C, 49.23, H, 2.86; N, 17.67. Found
%): C, 49.33, H, 2.88; N, 17.80.
N-(3-Iodophenyl)imidazo[1,2-a]pyrazine-2-carboxa-
8
6
H N
9 4
+
(
H N
9 5
-1
(%): C, 60.36, H, 3.81; N, 29.28.
mide (7d): Pale brown solid. IR (KBr, νmax, cm ): 3353, 3079,
N-(4-Methoxyphenyl)imidazo[1,2-a]pyrazine-2-carbo-
xamide (7i): Pale brown solid. IR (KBr, νmax, cm ): 3382,
932, 2853, 1626, 1562, 1477, 1436, 1414, 1314, 1111, 1010,
): δ 3.40 (s, 3H, OCH ),
.87 (s, 1H, imidazo[1,2-a]pyrazine-H), 6.90 (m, 1H,
imidazo[1,2-a]pyrazine-H), 7.05 (m, 1H, NH, imidazo[1,2-
a]pyrazine-H), 7.15 (s, 1H, imidazo[1,2-a]pyrazine-H), 7.28
d, 2H, Ar-H), 7.48 (d, 2H, Ar-H), 9.55 (brs, 1H, NH); LC-
MS: m/z 269.2 [M+H] . Anal. calcd. (%) for C14
62.68, H, 4.51; N, 20.88. Found (%): C, 62.78, H, 4.52; N, 20.90.
N-(3-Ethynylphenyl)imidazo[1,2-a]pyrazine-2-carbo-
xamide (7j): Pale brown solid. IR (KBr, νmax, cm ): 3457,
346, 3184, 3125,2358, 1672, 1589, 1549, 1481, 1421, 1359,
2
836, 2792, 1678, 1597, 1464, 1394, 1303, 1106, 982, 720;
-1
1
H NMR (400 MHz, DMSO-d
6
): δ 7.18 (t, 1H, Ar-H), 7.98 (d,
H, Ar-H), 8.17 (d, 1H, Ar-H), 8.35 (s, 1H, Ar-H), 8.62 (d,
H, C -H of pyrazine), 8.75 (d, 1H, C -H of pyrazine), 9.21
-H of pyrazine), 9.90 (s, 1H, imidazole ring proton),
2
8
6
1
1
1
17; H NMR (400 MHz, DMSO-d
6
3
5
6
(s, 1H, C
3
+
9
.88 (brs, 1H, NH); LC-MS: m/z 365.23 [M+H] . Anal. calcd.
OI: C, 42.88, H, 2.49; N, 15.39. Found (%):
(
%) for C13
H
9
N
4
(
C, 42.99, H, 2.47; N, 15.41.
+
H
12
N
4
O : C,
2
N-(4-Chlorophenyl)imidazo[1,2-a]pyrazine-2-carbo-
-1
xamide (7e): Pale brown solid. IR (KBr, νmax, cm ): 3454,
1
3
234, 2851, 1640, 1469, 1409, 1358, 1194, 1023, 740; H
NMR (400 MHz, DMSO-d ): δ 7.67 (d, 2H, Ar-H), 7.76 (d,
H, Ar-H), 8.01 (d, 1H, C -H of pyrazine), 8.64-8.67 (m, 2H,
-1
6
3
1
2
5
1
216; ; H NMR (400 MHz, DMSO-d ): δ 4.19 (s, 1H, ethynyl-
6
C
6
3
-H, C -H of pyrazine), 9.19 (s, 1H, imidazole ring proton),
O
I
NH2
Cu O
N
EtOH
MWI
2
N
Br
O
N
N
NH gas
3
O
3
K CO
1
3
2
2
Mukaiyama's reagent
Ionic liquid
DMF, MWI
EtOH
NaOH
N
N
NH Ar/R
N
OH
N
O
N
N
N
N
N
O
O
O
H2O
Ar/R NH2
7
a-l
4
5
6
a-l
Scheme-I