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PAPER
(s, 3 H), 2.84–2.80 (t, J = 6.0 Hz, 1 H), 2.63–2.57 (m, 1 H), 1.06 (s,
9 H).
Anal. Calcd for C22H27N3O5: C, 63.91; H, 6.58; N, 10.16. Found: C,
63.92; H, 6.60; N, 10.15.
13C NMR (75 MHz, CDCl3): d = 186.2, 163.3, 159.2, 145.7, 139.7,
139.0, 137.9, 134.8, 131.0, 129.7, 127.4, 125.8, 53.5, 53.4, 52.8,
50.4, 37.6.
Dimethyl 8-(tert-Butylimino)-5-(3-methoxyphenyl)-1-oxo-
2,3,5,8-tetrahydro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarbox-
ylate (4j)
Yellow solid; mp 88–90 °C.
IR (KBr): 3280, 2952, 1731, 1207, 1094 cm–1.
Anal. Calcd for C21H24ClN3O5: C, 58.13; H, 5.58; N, 9.68. Found:
C, 58.14; H, 5.59; N, 9.66.
Dimethyl 5-(3-Bromophenyl)-8-(tert-butylimino)-1-oxo-2,3,5,8-
tetrahydro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarboxylate
(4f)
1H NMR (400 MHz, CDCl3): d = 7.43–7.39 (m, 2 H), 7.29–7.22 (m,
2 H), 7.16–7.14 (d, J = 8.0 Hz, 1 H), 3.84 (s, 3 H), 3.55–3.36 (m, 5
H), 3.18–3.16 (m, 2 H), 2.35 (s, 3 H), 1.43 (s, 9 H).
White solid; mp 142–144 °C.
IR (KBr): 3310, 2957, 1735, 1276, 1067 cm–1.
1H NMR (300 MHz, CDCl3): d = 8.07 (s, 1 H), 7.71–7.69 (d, J = 6.0
Hz, 1 H), 7.39–7.24 (m, 2 H), 4.52 (s, 1 H), 4.19–4.13 (m, 1 H),
3.98–3.90 (m, 1 H), 3.85 (s, 3 H), 3.74 (s, 3 H), 2.83–2.75 (t,
J = 12.0 Hz, 1 H), 2.58–2.52 (m, 1 H), 1.00 (s, 9 H).
13C NMR (100 MHz, CDCl3): d = 169.0, 163.5, 161.5, 142.6, 140.8,
138.3, 137.6, 129.5, 128.5, 127.7, 124.2, 86.0, 58.2, 52.5, 37.6,
33.5, 30.1, 29.5, 27.65.
Anal. Calcd for C22H27N3O6: C, 61.53; H, 6.34; N, 9.78. Found: C,
61.52; H, 6.32; N, 9.80.
Dimethyl 8-(Cyclohexylimino)-1-oxo-5-phenyl-2,3,5,8-tetrahy-
dro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarboxylate (4k)
Yellow solid; mp 113 °C.
IR (KBr): 3425, 2927, 1723, 1270, 1070 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.40–7.29 (m, 5 H), 4.94 (s, 1 H),
3.90 (s, 3 H), 3.64–3.53 (m, 5 H), 3.25–3.17 (t, J = 12.0 Hz, 1 H),
2.04–1.97 (m, 2 H), 1.86–1.71 (m, 2 H), 1.57–1.26 (m, 8 H).
13C NMR (75 MHz, CDCl3): d = 174.0, 165.7, 163.5, 138.5, 138.3,
133.1, 131.4, 129.5, 129.3, 63.6, 60.7, 54.2, 52.7, 52.4, 34.7, 33.4,
33.1, 25.8, 23.8, 23.7.
13C NMR (75 MHz, CDCl3): d = 186.2, 163.2, 159.1, 145.8, 140.0,
138.9, 138.1, 133.9, 130.4, 129.9, 126.3, 122.9, 53.6, 53.4, 52.9,
50.5, 37.6.
Anal. Calcd for C21H24ClN3O5: C, 52.73; H, 5.06; N, 8.78. Found:
C, 52.75; H, 5.04; N, 8.77.
Dimethyl 8-(tert-Butylimino)-1-oxo-5-(4-tolyl)-2,3,5,8-tetrahy-
dro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarboxylate (4g)
Yellow solid; mp 80–83 °C.
IR (KBr): 3328, 2955, 1730, 1269, 1039 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.28–7.20 (m, 4 H), 4.88 (s, 1 H),
3.83 (s, 3 H), 3.62–3.36 (m, 5 H), 2.35 (s, 3 H), 1.81–1.78 (t, J = 6.0
Hz, 2 H), 1.36 (s, 9 H).
Anal. Calcd for C23H27N3O5: C, 64.93; H, 6.40; N, 9.88. Found: C,
64.90; H, 6.38; N, 9.90.
Dimethyl 8-(Cyclohexylimino)-5-(4-nitrophenyl)-1-oxo-2,3,5,8-
tetrahydro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarboxylate
(4l)
Orange solid; mp 90 °C.
IR (KBr): 3266, 2932, 1729, 1214, 1098 cm–1.
1H NMR (300 MHz, CDCl3): d = 8.79–8.76 (d, J = 9.0 Hz, 1 H),
8.28–8.26 (d, J = 6.0 Hz, 2 H), 7.46–7.43 (d, J = 9.0 Hz, 2 H), 3.67
(s, 3 H), 3.52–3.46 (m, 5 H), 2.39–2.35 (t, J = 6.0 Hz, 2 H), 2.04–
2.01 (m, 3 H), 1.76–1.50 (m, 4 H), 1.42–1.30 (m, 4 H).
13C NMR (100 MHz, CDCl3): d = 173.2, 169.0, 161.5, 138.7, 130.0,
129.3, 129.2, 127.6, 127.0, 86.1, 63.1, 59.0, 52.3, 46.2, 33.4, 29.4,
29.1, 21.2.
Anal. Calcd for C22H27N3O5: C, 63.91; H, 6.58; N, 10.16. Found: C,
63.93; H, 6.56; N, 10.17.
Dimethyl 8-(tert-Butylimino)-5-(4-methoxyphenyl)-1-oxo-
2,3,5,8-tetrahydro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarbox-
ylate (4h)
Yellow solid; mp 92–94 °C.
IR (KBr): 3319, 2957, 1709, 1275, 1066 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.32–7.27 (m, 2 H), 6.93–6.89 (m,
2 H), 4.88 (s, 1 H), 3.86 (s, 3 H), 3.80 (s, 3 H), 3.66–3.36 (m, 5 H),
3.36–3.32 (m, 1 H), 1.83–1.73 (m, 1 H), 1.36 (s, 9 H).
13C NMR (75 MHz, CDCl3): d = 173.7, 167.2, 167.0, 149.9, 147.7,
140.6, 140.2, 129.2, 124.0, 115.6, 84.0, 53.4, 51.6, 51.2, 46.3, 33.2,
30.0, 25.3, 24.3.
Anal. Calcd for C23H27N4O7: C, 58.72; H, 5.57; N, 11.91. Found: C,
58.73; H, 5.56; N, 11.93.
13C NMR (100 MHz, CDCl3): d = 173.2, 164.7, 159.9, 131.2, 130.5,
129.4, 128.4, 124.7, 114.0, 90.8, 62.8, 59.1, 55.2, 52.3, 46.2, 35.4,
30.5, 29.1.
Dimethyl 8-(Benzylimino)-1-oxo-5-phenyl-2,3,5,8-tetrahydro-
1H-pyrazolo[1,2-a]pyridazine-6,7-dicarboxylate (4m)
Yellow solid; mp 156 °C.
IR (KBr): 3430, 2950, 1726, 1272, 1081 cm–1.
1H NMR (300 MHz, CDCl3): d = 7.42–7.20 (m, 10 H), 4.96 (s, 2 H),
4.67 (s, 1 H), 3.91 (s, 3 H), 3.63–3.58 (m, 4 H), 3.44–3.36 (m, 1 H),
2.03–1.94 (m, 1 H), 1.25–1.00 (m, 1 H).
13C NMR (75 MHz, CDCl3): d = 172.0, 165.4, 163.4, 142.2, 140.0,
132.8, 129.7, 129.3, 128.2, 127.1, 126.4, 63.9, 56.7, 52.7, 46.1,
29.7.
Anal. Calcd for C22H27N3O6: C, 61.53; H, 6.34; N, 9.78. Found: C,
61.50; H, 6.35; N, 9.79.
Dimethyl 8-(tert-Butylimino)-1-oxo-5-(3-tolyl)-2,3,5,8-tetrahy-
dro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarboxylate (4i)
Yellow solid; mp 83–84 °C.
IR (KBr): 3279, 2955, 1728, 1269, 1039 cm–1.
1H NMR (400 MHz, CDCl3): d = 7.30–7.26 (m, 2 H), 7.07–7.02 (m,
2 H), 3.86 (s, 1 H), 3.66 (s, 3 H), 3.50–3.46 (t, J = 8.0 Hz, 2 H), 3.42
(s, 3 H), 2.36 (s, 3 H), 2.34–2.30 (t, J = 8.0 Hz, 2 H), 1.37 (s, 9 H).
Anal. Calcd for C24H23N3O5: C, 66.50; H, 5.35; N, 9.69. Found: C,
66.35; H, 5.30; N, 9.76.
13C NMR (100 MHz, CDCl3): d = 176.1, 167.4, 167.3, 149.8, 146.8,
138.5, 133.5, 129.6, 128.6, 124.8, 114.0, 90.8, 54.8, 52.3, 51.4,
51.3, 46.6, 30.5, 21.4.
Dimethyl 8-(Benzylimino)-5-(4-nitrophenyl)-1-oxo-2,3,5,8-tet-
rahydro-1H-pyrazolo[1,2-a]pyridazine-6,7-dicarboxylate (4n)
Orange solid; mp 86–88 °C.
Synthesis 2009, No. 10, 1689–1693 © Thieme Stuttgart · New York