Jul-Aug 2001
Quinoxalines X. A New and Convenient Synthesis
835
1-Ethyl-3-methyl-1H-pyrazolo[3,4-b]quinoxaline (12l).
1-Allyl-3-methyl-1H-pyrazolo[3,4-b]quinoxaline (12p).
This compound was obtained from the reaction of
This compound was obtained from the reaction of
compound 7b with ethyl iodide in 59% yield as yellow
needles (cyclohexane), mp 97-98 °C; ms: m/z 212 (M ); ir:
compound 7b with allyl bromide in 65% yield as yellow
needles (hexane), mp 88-90 °C; ms: m/z 224 (M ); ir: 3084,
+
+
3036, 2972, 2932, 1950, 1734, 1618, 1580, 1514, 1482, 1464,
1376, 1356, 1324, 1302, 1248, 1230, 1182, 1124, 1086, 1058,
994, 970, 932, 844, 864, 726, 656, 626, 608, 558, 426; H nmr
3018, 2918, 1646, 1618, 1582, 1560ß, 1514, 1498, 1482,
1464, 1416, 1388, 1350, 1320, 1286, 1246, 1224, 1184, 1122,
1062, 996, 932, 842, 766, 714, 648, 602, 562, 532, 424; H
1
1
(deuteriochloroform): δ 8.23-7.64 (m, 4H, aromatic), 4.59
nmr (deuteriochloroform): δ 8.24-7.65 (m, 4H, aromatic),
(q, J = 7.2 Hz, 2H, CH -CH ), 2.80 (s, 3H, 3-CH ), 1.58 (t, J =
3
2
3
6.12 (m, 1H, CH -CH=CH ), 5.29-5.15 (m, 4H, CH -
2
2
2
13
7.2 Hz, 3H, CH -CH ); C nmr (deuteriochloroform): δ
3
2
CH=CH , 2.81 (s, 3H, 3-CH ).
2)
3
142.2, 141.8, 141.4, 140.5, 136.3, 130.4, 130.1, 128.3, 127.0,
41.85, 14.71, 11.60.
Anal. Calcd. for C
H N : C, 69.62; H, 5.39; N, 24.98.
13 12 4
Found: C, 69.48; H, 5.44; N, 25.21.
Anal. Calcd. for C
H N : C, 67.91; H, 5.10; N, 26.39.
12 12 4
Ethyl (3-methyl-1H-pyrazolo[3,4-b]quinoxalin-1-yl)acetate
(12q).
Found: C, 67.73; H, 5.15; N, 26,24.
1-Isopropyl-3-methyl-1H-pyrazolo[3,4-b]quinoxaline (12m).
This compound was obtained from ethyl bromoacetate in 78%
yield as yellow needles (ethanol), mp 164-165.5 °C; ms: m/z 270
(M ); ir: 2988, 2938, 1748, 1580, 1500, 1474, 1460, 1378, 1348,
This compound was obtained from the reaction of compound
7b with 2-iodopropane in 76% yield as yellow needles (hexane),
+
+
mp 102-103.5 °C; ms: m/z 226 (M ); ir: 3068, 2974, 2930, 2874,
1322, 1286, 1218, 1184, 1122, 1028, 902, 932, 874, 774, 743,
1572, 1500, 1482, 1456, 1382, 1364, 1350, 1312, 1234, 1198,
1136, 1114, 1060, 970, 906, 842, 758, 730, 676, 622, 608, 542,
1
728, 684, 646, 602, 568, 426; H nmr (deuteriochloroform): δ
8.27-7.68 (m, 4H, aromatic), 5.32 (s, 2H, N-CH ), 4.23 (qu, J =
1
2
466, 422; H nmr(deuteriochloroform): δ 8.25-7.64 (m, 4H,
7.14 Hz, 2H, CH -CH ), 2.81 (s, 3H, 3-CH ), 1.27 (t, J = 7.14,
3
2
3
aromatic), 5.34 (qu, J = 6.7 Hz, 1H, H C-CH-CH ), 2.82 (s, 3H,
3
3
13
13
3H, CH -CH ); C nmr (deuteriochloroform): δ 168.0, 143.7,
3-CH ), 1.64 (d, J = 6.7 Hz, 6H, H C-CH-CH ); C nmr
3
2
3
3
3
143.4, 141.5, 140.8, 136.6, 130.7, 130.2, 128.4, 127.5, 61.73,
47.97, 14.02, 11.69.Anal. Calcd. for C N O : C, 62.21; H,
(deuteriochloroform): δ 142.0, 141.7, 141.4, 140.6, 136.5, 130.3,
130.1, 128.4, 127.0, 48.5, 21.8 (2), 11.7.
H
14 14
4 2
5.22; N, 20.73. Found: C, 62.14; H, 5.31; N, 20.65.
Anal. Calcd. for C
H N : C, 69.00; H, 6.24; N, 24.76.
13 14 4
Found: C, 69.14; H, 6.28; N, 24.64.
Ethyl 2-(3-methyl-1H-pyrazolo[3,4-b]quinoxalin-1-yl)propi-
onate (12r).
1-Butyl-3-methyl-1H-pyrazolo[3,4-b]quinoxaline (12n).
This compound was obtained from the reaction of
This compound was obtained from the reaction of
compound 7b with 1-iodobutane in 48% yield as yellow
needles (hexane), mp 57-60 °C; ms: m/z 240 (M ); ir: 3058,
compound 7b with ethyl 2-bromopropionate in 69% yield as
yellow needles (ethanol), mp 87-89 °C; ms: m/z 284 (M ); ir:
+
+
2952, 2928, 2868, 1618, 1578, 1560, 1498, 1482, 1464, 1414,
1376, 1350, 1324, 1242, 1222, 1182, 1122, 1070, 1012, 976,
922, 758, 726, 694, 638, 602, 422; H nmr (deuterio-
2986, 2916, 1578, 1500, 1480, 1452, 1386, 1348, 1294, 1210,
1196, 1156, 1136, 1122, 1086, 1034, 964, 890, 864, 766, 728,
702, 670, 638, 600, 540, 464, 424; H nmr (deuterio-
1
1
chloroform): δ 8.25-7.66 (m, 4H, aromatic), 4.54 (t, J =7.2 Hz,
chloroform): δ 8.28-7.69 (m, 4H, aromatic), 5.78 (q, J = 7.4
2H, N-CH ), 1.99 (q, J = 7.4 Hz, 2H, CH -CH -CH -CH ),
2
3
2
2
2
Hz, 1H, N-C-H), 4.18 (q, J = 7.1 Hz, 2H, Ester-CH ), 2.83
2
1.39 (sx, J = 7.5 Hz, 2H, CH -CH -CH -CH ), 0.97 (t, J = 7.4
3
2
2
2
(s, 3H, 3-CH ) 2.02 (d, J = 7.4, 3H, CH -CH-), 1.18 (t, J = 7.1,
3
3
13
Hz, 3H, CH -CH -CH -CH ); C nmr (deuteriochloroform):
13
3
2
2
2
3H, Ester-CH ); C nmr (deuteriochloroform): δ 181.7,
3
δ 142.6, 141.8, 141.6, 140.5, 136.2, 130.3, 130.1, 128.4,
127.0, 46.67, 31.51, 19.91, 13.59, 11.61.
170.5, 143.2, 141.4, 140.9, 136.7, 130.6, 130.2, 128.4, 127.3,
61.61, 54.39, 16.13, 13.96, 11.71.
Anal. Calcd. for C
H N : C, 69.97; H, 6.71; N, 23.31.
14 16 4
Anal. Calcd. for C
H N O : C, 63.37; H, 5.67; N, 19.71.
15 16 4 2
Found: C, 70.21; H, 6.85; N, 23.19.
Found: C, 63.47; H, 5.76; N, 19.55.
1-Isobutyl-3-methyl-1H-pyrazolo[3,4-b]quinoxaline (12o).
1-Benzyl-3-methyl-1H-pyrazolo[3,4-b]quinoxaline (12s).
This compound was obtained from the reaction of
This compound was obtained from the reaction of compound
compound 7b with 2-bromobutane in 42% yield as yellow
7b with benzyl bromide in 37% yield as yellow needles (hexane),
+
needles (hexane), mp 81-83 °C; ms: m/z 240 (M ); ir: 3044,
+
mp 156-158 °C; ms: m/z 274 (M ); ir: 3064, 2918, 1684, 1604,
2960, 2926, 2872, 2360, 1940, 1844, 1734, 1618, 1576, 1560,
1510, 1498, 1484, 1466, 1430, 1404, 1386, 1352, 1320, 1286,
1246, 1226, 1182, 1122, 1072, 986, 942, 880, 842, 764, 7289,
1578, 1512, 1498, 1480, 1456, 1382, 1352, 1316, 1266, 1240,
1206, 1178, 1120, 1104, 1072, 982, 930, 904, 842, 760, 730, 712,
1
680, 638, 618, 604, 576, 422; H nmr (deuteriochloroform): δ
1
708, 642, m 622, 600; H nmr (deuteriochloroform): δ
8.20-7.58 (m, 4H, aromatic/quinoxaline) 7.37-7.17 (m, 5H,
8.25-7.66 (m, 4H, aromatic), 4.35 (d, J = 7.4 Hz, 2H, N-CH ),
2
aromatic/phenyl), 5.68 (s, 2H, benzyl-CH ), 2.75 (s, 3H, 3-CH );
2.81 (s, 3H, 3-CH ), 2.47 (m, 1H, isobutyl-CH), 0.97 (d, J =
2
3
3
13
13
C nmr (deuteriochloroform): δ 143.1, 142.9, 141.9, 140.9,
137.0, 136.6, 130.7, 130.4, 128.8, 128.2, 128.2, 128.1, 128.0,
127.9 , 127.4,50.81, 11.95.
6.7, 6H, isobutyl-CH ); C nmr (deuteriochloroform): δ
143.0, 141.7, 141.7, 140.6, 136.1, 130.3, 130.1, 128.5, 127.0,
54.19, 28.93, 20.25, 20.02, 11.63.
3
Anal. Calcd. for C
H N : C, 74.43; H, 5.14; N, 20.42.
Anal. Calcd. for C
H N : C, 69.97; H, 6.71; N, 23.31.
17 14 4
14 16 4
Found: C, 70.13; H, 6.81; N, 23.25.
Found: C, 74.51; H, 5.18; N, 20.38.