612 R. Mahesh et al.
(m, 1H, quinoxaline), 7.92 (m, 2H, quinoxaline), 6.90
(m, 4H, phenyl), 4.06 (t, 2H, NCH2, piperazine), 3.76 (s,
3H, OCH3), 3.56 (t, 2H, NCH2, piperazine), 3.44 (t, 2H,
NCH2, piperazine), 3.29 (t, 2H, NCH2, piperazine); IR
(KBr, cm−1): 3050, 3000, 2950, 2900 (C-H), 1635 (C=O),
1498 (CH2), 1370 (CH3); mass spectra (ESI) of the com-
pound exhibited the molecular ion peak at m/z 349.2
(M + 1+).
(4-Benzylpiperazin-1-yl)(quinoxalin-2-yl)methanone
hydrochloride (4g)
Yield: 74%; mp: 216–220°C; 1H NMR (DMSO-d6) (δ)
ppm:12.33 (s, 1H, salt proton), 9.21 (s, 1H, aromatic
proton) 8.13 (m, 2H, aromatic protons), 7.86 (m, 2H,
aromatic protons), 7.75 (s, 2H, aromatic protons), 7.44
(s, 3H, aromatic protons), 4.84 (d, 1H, piperazine), 4.55
(d, 1H, piperazine), 4.43 (s, 2H, benzylic CH2), 4.12 (t,
1H, piperazine), 3.77 (t, 1H, piperazine), 3.57 (d, 1H, pip-
erazine), 3.13 (m, 3H, piperazine); IR (KBr, cm−1): 3045,
2930, 2870 (C-H), 1640 (C=O), 1480 (CH2); mass spectra
(ESI) of the compound exhibited the molecular ion peak
at m/z 333.2 (M + 1+).
[4-(4-Methoxyphenyl)piperazin-1-yl](quinoxalin-2-yl)
methanone (4c)
Yield: 52%; mp: 94–96°C; 1H NMR (CDCl3) (δ) ppm: 9.25
(s, 1H, quinoxaline), 8.16 (m, 1H, quinoxaline), 8.08 (m,
1H, quinoxaline), 7.97 (m, 2H, quinoxaline), 6.96 (m, 2H,
phenyl), 6.90 (m, 2H, phenyl), 4.06 (t, 2H, NCH2, pipera-
zine), 3.73 (s, 3H, OCH3), 3.56 (t, 2H, NCH2, piperazine),
3.44 (t, 2H, NCH2, piperazine), 3.29 (t, 2H, NCH2, pipera-
zine); IR (KBr, cm−1): 3045, 3000, 2950, 2900, 2830 (C-H),
1640 (C=O), 1470 (CH2), 1370 (CH3); mass spectra (ESI) of
the compound exhibited the molecular ion peak at m/z
349.2 (M + 1+).
(4-Methylpiperazin-1-yl)(quinoxalin-2-yl)methanone
(4h)
Yield: 64%; 1H NMR (CDCl3) δ ppm: 9.18 (s, 1H, quinoxa-
line) 8.17 (m, 1H, quinoxaline), 8.11 (m, 1H, quinoxa-
line), 7.88 (m, 2H, quinoxaline), 3.93 (t, 2H, piperazine)
3.84 (t, 2H, piperazine) 2.66 (t, 2H, piperazine), 2.57 (t,
2H, piperazine), 2.40 (s, 3H, methyl); IR (KBr, cm−1): 3045,
2930, 2870 (C-H), 1640 (C=O), 1480 (CH2); mass spectra
(ESI) of the compound exhibited the molecular ion peak
at m/z 257.3 (M + 1+).
(4-(4-Chlorophenyl)piperazin-1-yl)(quinoxalin-2-yl)
methanone (4d)
1
Yield: 71%; mp: 124–126°C; H NMR (CDCl3) (δ) ppm:
9.24 (s, 1H, quinoxaline), 8.15 (m, 1H, quinoxaline),
8.08 (m, 1H, quinoxaline), 7.94 (m, 2H, quinoxaline),
7.29 (m, 2H, phenyl), 7.00 (m, 2H, phenyl), 4.03 (t, 2H,
NCH2, piperazine), 3.53 (t, 2H, NCH2, piperazine), 3.42
(t, 2H, NCH2, piperazine), 3.29 (t, 2H, NCH2, piperazine);
IR (KBr, cm−1): 3038, 3004, 2956, 2905, 2856 (C-H), 1636
(C=O); mass spectra (ESI) of the compound exhibited the
molecular ion peak at m/z 353.0 (M + 1+).
(4-Ethylpiperazin-1-yl)(quinoxalin-2-yl)methanone
hydrochloride (4i)
Yield: 66%; mp: 240–242°C; H NMR (CDCl3) (δ) ppm:
1
9.16 (s, 1H, quinoxaline) 8.15 (m, 1H, quinoxaline), 8.10
(m, 1H, quinoxaline), 7.85 (m, 2H, quinoxaline), 3.91 (t,
2H, piperazine) 3.80 (t, 2H, piperazine) 2.63 (t, 2H, pip-
erazine), 2.54 (t, 2H, piperazine), 2.38 (q, 2H, methylene),
1.38 (t, 3H, methyl). IR (KBr, cm−1): 3050, 3000, 2900, 2860
(C-H), 1635 (C=O), 1470 (CH2), 1360 (CH3); mass spectra
(ESI) of the compound exhibited the molecular ion peak
at m/z 271.1 (M + 1+).
(4-(3-Chlorophenyl)piperazin-1-yl)(quinoxalin-2-yl)
methanone (4e)
Yield: 81%; mp: 63–65°C; 1H NMR (CDCl3) (δ) ppm: 9.23
(s, 1H, quinoxaline), 8.10 (m, 1H, quinoxaline), 8.07 (m,
1H, quinoxaline), 7.93 (m, 2H, quinoxaline), 7.36 (t, 1H,
phenyl), 7.06 (m, 3H, phenyl), 4.04 (t, 2H, NCH2, pipera-
zine), 3.54 (t, 2H, NCH2, piperazine), 3.41 (t, 2H, NCH2,
piperazine), 3.27 (t, 2H, NCH2, piperazine); IR (KBr, cm−1):
3038, 3004, 2956, 2905, 2856 (C-H), 1636 (C=O); mass
spectra (ESI) of the compound exhibited the molecular
ion peak at m/z 353.2 (M + 1+).
(4-Allylpiperazin-1-yl)(quinoxalin-2-yl)methanone (4j)
Yield: 68%; 1H NMR (CDCl3) (δ) ppm: 9.24 (s, 1H, quinoxa-
line) 8.18 (dd, 1H, quinoxaline), 8.08 (dd, 1H, quinoxaline),
7.90 (m, 2H, quinoxaline), 6.14 (m, 1H, methine), 5.50 (m,
2H, olefinic methylene) 4.23 (s, 4H, piperazine) 3.52 (d, 2H,
piperazine) 3.14 (q, 4H, 2H piperazine, 2H methylene). IR
(KBr, cm−1): 3050, 3000, 2900, 2860 (C-H), 1635 (C=O), 1470
(CH2), 1360 (CH3); mass spectra (ESI) of the compound
exhibited the molecular ion peak at m/z 283.2 (M + 1+).
Quinoxalin-2-yl(4-(3-(trifluoromethyl)phenyl)
piperazin-1-yl)methanone (4f)
Yield: 65%; mp: 150–152°C; H NMR (CDCl3) (δ) ppm:
N-(2-(dimethylamino)ethyl)quinoxalin-2-carboxamide
hydrochloride (5a)
1
Yield: 54%; mp: 44–46°C; 1H NMR (CDCl3) (δ) ppm: 9.66
(s, 1H, quinoxaline), 8.16 (dd, 1H, quinoxaline), 8.10 (dd,
1H, quinoxaline), 8.08 (s, 1H, NH) 7.86 (m, 2H, quinoxa-
line), 4.36 (t, 2H, CONHCH2), 2.88 (t, 2H, CH2NMe2),
2.54 (s, 6H, NMe2); IR (KBr, cm−1): 3300 (N-H), 3030, 2980,
2850 (C-H), 1665 (C=O), 1550 (N-H), 1460 (CH2); mass
spectra of the compound exhibited the molecular ion
peak at m/z 245.1 (M + 1+).
9.26 (s, 1H, quinoxaline), 8.14 (m, 1H, quinoxaline), 8.09
(m, 1H, quinoxaline), 7.90 (m, 2H, quinoxaline), 7.40 (t,
1H, phenyl), 7.16 (m, 3H, phenyl), 4.09 (t, 2H, NCH2, pip-
erazine), 3.57 (t, 2H, NCH2, piperazine), 3.43 (t, 2H, NCH2,
piperazine), 3.28 (t, 2H, NCH2, piperazine); IR (KBr, cm−1):
3040, 3000, 2950, 2900, 2850 (C-H), 1635 (C=O); mass
spectra (ESI) of the compound exhibited the molecular
ion peak at m/z 387.1 (M + 1+).
Journal of Enzyme Inhibition and Medicinal Chemistry