906
K. R. Rao, A. Raghunadh, R. Mekala, S. B. Meruva, K. R. Ganesh,
T. Krishna, D. Kalita, E. Laxminarayana, and M. Pal
Vol 53
1
(t, J= 5.0 Hz, 2H, CH2), 3.51 (t, J= 4.6 Hz, 2H, CH2), 3.67
(t, J= 4.6 Hz, 2H, CH2), 3.80 (s, 2H), 3.85 (s, 3H, OCH3), 6.85 (dd,
J= 2.4 Hz,1H, ArH), 7.05 (s, 2H, ArH), 7.25 (s, 1H, NH), 7.45–7.64
(m, 5H, ArH), 7.81 (dd, J= 1.2 Hz, 1H, ArH), 7.93–7.99 (m, 4H,
ArH); 13C NMR (100 MHz, CDCl3) δ: 41.1 (CH2), 45.5 (N–CH2,
2×CH2), 48.6 (N–CH2, 2×CH2), 55.8 (CH3), 100.3, 108.6, 111.9,
112.5, 122.9, 126.8, 126.9, 127.3 (2 × CH), 127.7 (2 × CH), 128.7,
128.8, 129.4, 129.7, 131.3, 138.7, 139.0, 140.0, 148.2, 153.7, 154.1,
170.2; MS: m/z (%) = 478.30 (M + 1). HRMS: [MH]+ 478.2231,
calculated mass: 478.2243, molecular formula: C29H28N5O2.
Furan-2-yl (4-(3-phenylquinoxalin-2-yl) piperazin-1-yl)
methanone (7b).
Yellow color syrup; yield: 82%; H NMR (400 MHz, CDCl3)
δ: 0.72–0.88 (m, 2H, CH2), 1.09–1.33 (m, 2H, CH2), 1.68–1.73
(m, 1H, CH), 3.27 (t, J = 4 Hz, 4H, 2 × CH2), 3.63 (t, J = 5 Hz,
4H, 2 × CH2), 7.46–7.55 (m, 4H, ArH), 7.61–7.64 (m, 2H,
ArH), 7.82 (d, J = 6.8 Hz, 1H, ArH), 8.00–8.01 (m, 2H, ArH);
13C NMR (100 MHz, CDCl3) δ: 7.3 (2 × CH), 10.9, 44.8
(N–CH2, 2 × CH2), 48.5 (N–CH2, 2 × CH2), 126.6, 126.9, 127.7
(2× CH), 128.6, 128.7 (2× CH), 129.3, 129.6, 138.6, 139.04,
140.0, 148.0, 153.7, 172.2; MS: m/z (%) = 359.10 (M + 1).
HRMS: [MH]+ 359.1884, calculated mass: 359.1872, molecular
formula: C22H23N4O.
(4-(tert-Butyl)phenyl)(4-(3-phenylquinoxalin-2-yl)piperazin-
1-yl)methanone (7e).
1
Brown color syrup; yield: 89%; H NMR (400 MHz, CDCl3)
δ: 3.36 (t, J = 4.8 Hz, 4H, 2 × CH2), 3.89 (t, J = 5.0 Hz, 4H,
2 × CH2), 6.47 (dd, J = 2.0 Hz, 1H, ArH), 6.55 (m, 1H, ArH),
7.0 (d, J = 7.6 Hz, 1H, ArH), 7.28–7.29 (m, 1H, ArH), 7.54–
7.56 (m, 4H, ArH), 7.61–7.66 (m, 1H, ArH), 7.85 (d, J = 6.8 Hz,
1H, ArH), 8.0–8.02 (m, 2H, ArH); 13C NMR (100 MHz, CDCl3)
δ: 44.8 (N–CH2, 2 × CH2), 48.7 (N–CH2, 2 × CH2), 111.3, 111.8,
116.9, 118.8, 126.7, 126.9, 127.8 (2 × CH), 128.6 (2 × CH),
129.7, 138.9, 140.0, 146.6, 147.5, 148.1, 153.7, 159.3, 161.3;
MS: m/z (%) = 385.20 (M + 1). HRMS: [MH]+ 385.1679, calcu-
lated mass: 385.1665, molecular formula: C23H21N4O2.
1-(4-(3-Phenylquinoxalin-2-yl)piperazin-1-yl)-2-(thiophen-2-yl)
ethanone (7c).
1
Yellow color syrup; yield: 86%; H NMR (400 MHz, CDCl3)
δ: 1.31 (s, 9H, 3 × CH3), 3.29–3.31 (m, 8H, 4 × CH2), 7.27–7.31
(m, 3H, ArH), 7.33–7.55 (m, 7H, ArH), 7.8 (d, J = 7.8 Hz, 1H,
ArH), 7.99–8.01 (m, 2H, ArH); 13C NMR (100 MHz, CDCl3) δ:
31.0 (3 × CH3), 34.6, 43.2 (N–CH2, 2 × CH2), 48.8 (N–CH2,
2 × CH2), 113.8, 126.7, 126.8 (2 × CH), 126.9, 127.7 (2 × CH),
128.1, 128.6 (2 × CH), 128.7, 129.0 (2 × CH), 132.4, 138.9,
140.02, 152.9, 153.7, 154.6, 167.1, 170.6; MS: m/z
(%) = 451.30 (M + 1). HRMS: [MH]+ 451.2504, calculated mass:
451.2498, molecular formula: C29H31N4O.
(4-Fluorophenyl)(4-(3-phenylquinoxalin-2-yl)piperazin-1-yl)
methanone (7f).
Yellow color solid; mp: 128–130°C, yield: 92%; 1H NMR
(400MHz, CDCl3) δ: 3.23 (t, J = 5.0 Hz, 4H, 2 × CH2), 3.54
(t, J = 5.2Hz, 2H, CH2), 3.65 (t, J = 5.2 Hz, 2H, CH2), 3.90 (s, 2H,
CH2), 6.88–6.94 (m, 2H, ArH), 7.18–7.19 (m, 1H, ArH), 7.47–
7.51 (m, 4H, ArH), 7.61–7.63 (m, 1H, ArH), 7.81 (d, J = 7.0 Hz,
1H, ArH), 7.95–8.00 (m, 3H, ArH); 13C NMR (100 MHz, CDCl3)
δ:34.9 (CH2), 45.4 (N–CH2, 2 × CH2), 48.4 (N–CH2, 2 × CH2),
124.6, 125.9, 126.7, 126.8 (2 × CH), 127.6 (2× CH), 128.3, 128.6,
128.7 (2× CH), 129.6, 136.1, 138.6, 138.9, 139.9, 147.9, 153.5,
168.4; MS: m/z (%) = 415.20 (M + 1). HRMS: [MH]+ 415.1612,
calculated mass: 415.1593, molecular formula: C24H23N4OS.
Cyclopropyl-(4-(3-phenylquinoxalin-2-yl)piperazin-1-yl)methanone
(7d).
Yellow color solid; mp: 185–188°C, yield: 78%; 1H NMR
(400 MHz, CDCl3) δ: 3.25 (s, 4H, 2 × CH2), 3.51 (s, 4H,
2 × CH2), 7.08–7.10 (m, 3H, ArH), 7.38–7.52 (m, 7H, ArH), 7.8
(d, J = 7.8 Hz, 1H, ArH), 8.02–8.11 (m, 2H, ArH); 13C NMR
(100 MHz, CDCl3) δ: 43.3 (N–CH2, 2 × CH2), 48.7 (N–CH2,
2 × CH2), 115.12 (2 × CH), 126.3, 126.4, 126.8, 126.9, 127.7
(2 × CH), 128.3 (2 × CH), 128.6, 128.7, 129.3, 129.3, 129.4,
129.7, 139.9, 148.1, 153.6, 164.2, 169.6; MS: m/z (%) = 413.10
(M + 1). HRMS: [MH]+ 413.1766, calculated mass: 413.1778,
molecular formula: C25H22N4OF.
General procedure for the synthesis of compound 8.
A
mixture of 2-chloro-3-phenylquinoxaline (3, 1.0 equiv) and
appropriate amine (1.0 equiv) was heated to 100–110°C for
8–10 h. The progress of the reaction was monitored by TLC.
After completion of the reaction, the crude isolated was purified
by column chromatography using EtOAc/n-hexane(20:80) on
230–400 silica gel.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet