135.4, 134.5, 129.1, 123.8, 62.8, 54.7, 54.6, 22.4, 21.4, 13.8, 11.1;
HRMS: calcd. for C18H20ClN3O5 (M+): 393.1091, found: 393.1099.
4.23–4.02 (m, 4H), 2.17 (s, 3H), 1.87–1.82 (m, 2H), 1.15 (t, J =
7.2 Hz, 3H), 0.98 (t, J = 7.4 Hz, 3H); 13C NMR (CDCl3) d 170.3,
158.9, 147.5, 147.4, 144.5, 136.6, 129.8, 128.1, 123.4, 62.4, 54.8,
53.6, 21.6, 19.7, 13.7, 11.0; HRMS: calcd. for C18H20N4O7 (M+):
404.1332, found: 404.1336.
Ethyl 2-(2ꢀ-tert-butyl-4ꢀ-chloro-3ꢀ-oxopyridazin-5ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (7c)
White solid. Yield: 60%. Mp: 121.4–122.6 ◦C. 1H NMR (CDCl3)
d 8.27 (d, J = 9.0 Hz, 2H), 7.73 (d, J = 9.0 Hz, 2H), 7.27 (s,
1H), 4.31–4.18 (m, 2H, nonequivalent geminal hydrogens), 2.05
(s, 3H), 1.64 (s, 9H), 1.25 (t, J = 7.1 Hz, 3H); 13C NMR (CDCl3) d
170.7, 157.1, 147.6, 145.7, 142.6, 136.1, 132.9, 129.1, 123.8, 66.7,
62.7, 54.5, 27.6, 22.1, 13.8; HRMS: calcd. for C19H22ClN3O5 (M+):
407.1248, found: 407.1249.
Ethyl 2-(2ꢀ-tert-butyl-5ꢀ-nitro-3ꢀ-oxopyridazin-4ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (8c)
◦
1
Yellow solid. Yield: 72%. Mp: 99.7–100.9 C. H NMR (CDCl3)
d 8.14 (d, J = 8.8 Hz, 2H), 7.88 (s, 1H), 7.64 (d, J = 9.2 Hz,
2H), 4.16–3.98 (m, 2H, nonequivalent geminal hydrogens), 2.19
(s, 3H), 1.65 (s, 9H), 1.15 (t, J = 7.2 Hz, 3H); 13C NMR (CDCl3) d
170.6, 159.5, 147.5, 147.1, 144.7, 137.0, 128.1, 127.9, 123.3, 67.5,
62.3, 53.5, 27.6, 20.1, 13.7; HRMS: calcd. for C19H22N4O7 (M+):
418.1521, found: 418.1523.
Ethyl 2-(4ꢀ-chloro-2ꢀ-phenyl-3ꢀ-oxopyridazin-5ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (7d)
Yellow solid. Yield: 65%. Mp: 130.1–130.8 ◦C. 1H NMR (CDCl3)
d 8.30 (d, J = 8.8 Hz, 2H), 7.78 (d, J = 8.8 Hz, 2H), 7.65–7.43
(m, 5H), 7.33 (s, 1H), 4.33–4.20 (m, 2H, nonequivalent geminal
hydrogens), 2.12 (s, 3H), 1.28 (t, J = 7.2 Hz, 3H); 13C NMR
(CDCl3) d 170.5, 156.5, 147.7, 145.4, 143.3, 141.1, 136.6, 135.4,
129.1, 128.8, 128.7, 123.9, 123.4, 62.9, 54.7, 22.2, 13.8; HRMS:
calcd. for C21H18ClN3O5 (M+): 427.0935, found: 427.0941.
Ethyl 2-(2ꢀ-phenyl-5ꢀ-nitro-3ꢀ-oxopyridazin-4ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (8d)
Yellow solid. Yield: 75%. Mp: 194.5–195.8 ◦C. 1H NMR (CDCl3)
d 8.18 (d, J = 8.8 Hz, 2H), 8.08 (s, 1H), 7.71 (d, J = 8.8 Hz,
2H), 7.56–7.45 (m, 5H), 4.18–4.03 (m, 2H, nonequivalent geminal
hydrogens), 2.23 (s, 3H), 1.16 (t, J = 7.2 Hz, 3H); 13C NMR
(CDCl3) d 170.2, 158.9, 147.6, 147.2, 144.4, 140.5, 138.3, 130.6,
129.3, 129.1, 128.1, 125.1, 123.5, 62.5, 53.9, 19.8, 13.7; HRMS:
calcd. for C21H18N4O7 (M+): 438.1175, found: 438.1173.
Ethyl 2-(2ꢀ-benzyl-4ꢀ-chloro-3ꢀ-oxopyridazin-5ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (7e)
White solid. Yield: 64%. Mp: 115.8–116.9 ◦C. 1H NMR (CDCl3)
d 8.26 (d, J = 9.2 Hz, 2H), 7.70 (d, J = 8.8 Hz, 2H), 7.50–7.35 (m,
5H), 7.17 (s, 1H), 5.33 (dd, J = 13.6 Hz, 2H, nonequivalent geminal
hydrogens), 4.30–4.12 (m, 2H, nonequivalent geminal hydrogens),
2.03 (s, 3H), 1.24 (t, J = 7.2 Hz, 3H); 13C NMR (CDCl3) d
170.5, 156.8, 147.6, 145.4, 143.5, 135.7, 135.1, 135.0, 129.4, 129.1,
128.7, 128.4, 123.9, 62.8, 56.5, 54.6, 22.2, 13.8; HRMS: calcd. for
C22H20ClN3O5 (M+): 441.1091, found: 441.1096.
Ethyl 2-(2ꢀ-benzyl-5ꢀ-nitro-3ꢀ-oxopyridazin-4ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (8e)
Yellow viscous liquid. Yield: 75%. 1H NMR (CDCl3) d8.13 (d, J =
8.8 Hz, 2H), 7.95 (s, 1H), 7.61 (d, J = 9.2 Hz, 2H), 7.45–7.35 (m,
5H), 5.34 (dd, J = 13.6 Hz, 2H, nonequivalent geminal hydrogens),
4.10–3.92 (m, 2H, nonequivalent geminal hydrogens), 2.16 (s, 3H),
1.02 (t, J = 7.2 Hz, 3H);13C NMR (CDCl3) d 170.1, 158.8, 147.5,
147.4, 144.4, 137.2, 134.7, 130.1, 129.1, 128.8, 128.6, 128.0, 123.4,
62.4, 56.7, 53.6, 19.7, 13.6; HRMS: calcd. for C22H20N4O7 (M+):
452.1332, found: 452.1332.
Compounds 8a–e
Compounds 8a–e were prepared by the same procedure as
that for compounds 6a–f, using 4-chloro-5-nitro-pyridazinone as
electrophile to quench the VNS reaction. Except that the second
step was carried out at room temperature.
Compounds 9a–f
Compounds 9a–f were prepared by the same procedure as that for
compounds 6a–f, using 4,5-dichloropyridazinone as electrophile
to quench the VNS reaction. Except that the second step was
carried out at 40◦ C.
Ethyl 2-(2ꢀ-ethyl-5ꢀ-nitro-3ꢀ-oxopyridazin-4ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (8a)
Yellow solid. Yield: 72%. Mp: 99.7–100.9 ◦C. 1H NMR (CDCl3) d
8.16 (d, J = 9.2 Hz, 2H), 7.95 (s, 1H), 7.65 (d, J = 9.2 Hz, 2H), 4.30–
4.21 (m, 2H, nonequivalent geminal hydrogens), 4.14–4.05 (m,
2H, nonequivalent geminal hydrogens), 2.18 (s, 3H), 1.41 (t, J =
7.2 Hz, 3H), 1.16 (t, J = 7.2 Hz, 3H); 13C NMR (CDCl3) d 170.3,
158.7, 147.5, 144.5, 136.6, 129.9, 128.1, 123.4, 62.4, 53.6, 48.6,
19.7, 13.7, 13.2; HRMS: calcd. for C17H18N4O7 (M+): 390.1175,
found: 390.1156.
Ethyl 2-{[5ꢀ-(4ꢀꢀ-methoxyphenyl)-1ꢀ,3ꢀ,4ꢀ-oxadiazol-2ꢀ-yl]methyl}-
2-(4ꢀꢀꢀ-nitrophenyl)propanoate (9a)
Yellow solid. Yield: 74%. Mp: 123.6–124.5 ◦C. 1H NMR (CDCl3)
d 8.22 (d, J = 8.8 Hz, 2H), 7.78 (d, J = 9.2 Hz, 2H), 7.56 (d,
J = 8.8 Hz, 2H), 6.96 (d, J = 8.8 Hz, 2H), 4.28–4.20 (m, 2H,
nonequivalent geminal hydrogens), 3.87 (s, 3H), 3.67 (dd, J =
15.2 Hz, 2H, nonequivalent geminal hydrogens), 1.83 (s, 3H), 1.23
(t, J = 7.2 Hz, 3H); 13C NMR (CDCl3) d173.4, 164.8, 162.6, 162.4,
148.6, 147.2, 128.4, 127.2, 123.8, 115.9, 114.5, 62.1, 55.5, 49.7, 35.4,
22.4, 13.9; HRMS: calcd. for C21H21N3O6 (M+): 411.1430, found:
411.1431.
Ethyl 2-(2ꢀ-propyl-5ꢀ-nitro-3ꢀ-oxopyridazin-4ꢀ-yl)-2-
(4ꢀꢀ-nitrophenyl)propanoate (8b)
Yellow solid. Yield: 72%. Mp: 119.9–120.7 ◦C. 1H NMR (CDCl3)
d 8.16 (d, J = 9.2 Hz, 2H), 7.95 (s, 1H), 7.65 (d, J = 9.2 Hz, 2H),
1296 | Org. Biomol. Chem., 2008, 6, 1293–1297
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The Royal Society of Chemistry 2008
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