Reactivity of Pyridazin-3(2H) Thiones 339
for C19H18N2OS (322.42); C: 70.77; H: 5.62; N: 8.68;
S: 9.94; found: C, 71.20; H, 6.06; N, 8.60; S, 9.00;
HRMS calcd. for C19H18N2OS 322.42; found 322.11.
NH), 8.30 (s, 2H, NH), 7.14–7.90 (m, 8H, Ar-H),
6.90 (s, 1H, 5-H), 4.22 (s, 2H, CH2), 3.81 (s, 3H,
OCH3), 2.41 (s, 3H, CH3) ppm; Anal. calcd. for
C19H20N4O (320.39); C: 71.22; H: 6.29; N: 17.48;
found: C, 69.96; H, 6.31; N, 17.33; HRMS calcd. for
C19H20N4O 320.39; found 320.1.
4-(2-Methoxybenzyl)-6-(4-methylphenyl)-2-methyl-
pyridazine-3(2H)-thione 7e. Colourless crystals
2.80 g, 83% yield, mp 127–129◦C; IR (KBr pellet):
1630 (s) for (C N), 1267–1274 (v) for (C S) cm−1;
1H NMR (CDCl3, 200 MHz): δ 7.26–8.16 (m, 8H,
Ar-H), 6.76 (s, 1H, 5-H), 4.22 (s, 2H, CH2), 3.88
(s, 3H, OCH3), 3.32 (s, 3H, N CH3), 2,63 (s, 3H,
CH3) ppm; Anal. calcd. for C20H20N2OS (336.45); C:
71.39; H: 5.99; N: 8.32; S: 9.52; found: C, 70.83; H,
6.28; N, 8.09; S, 9.30; HRMS calcd. for C20H20N2OS
336.45; found 336.13.
(3E)-6-(4-Chlorophenyl)-4-(-2-Methoxybenzyl)-
pyridazin-3(2H)-one
Hydrazone
8f. Colourless
crystals 2.4 g, 70% yield, mp 146–148◦C; IR (KBr
pellet): 3100–3350 (br) for (NH), 1635 (s) for (C N)
cm−1; 1H NMR (CDCl3, 200 MHz): δ 8.60 (s, 1H,
NH), 8.37 (s, 2H, NH), 6.96–7.65 (m, 8H, Ar-H),
6.77 (s, 1H, 5-H), 4.27 (s, 2H, CH2), 3.87 (s, 3H,
OCH3) ppm; Anal. calcd. for C18H17ClN4O (340.81);
C: 63.43; H: 5.027; N: 16.43; found; C, 63.30; H, 5.10;
N, 16.02; S, 8.40; HRMS calcd. for C18H17ClN4O
340.81; found 340.10.
6-(4-Chlorophenyl)-4-(2-methoxybenzyl)-2-methyl-
pyridazine-3(2H)-thione 7f. Colourless crystals 2.15
g, 60% yield, mp 150–152◦C; IR (KBr pellet): 1630
1
(s) for (C N), 1267–1274 (v) for (C S) cm−1; H
N[4-(2-Methoxybenzyl)-6-(4-methylphenyl)-
NMR (CDCl3, 200 MHz): δ 7.66–8.65 (m, 8H, Ar-H),
6.78 (s, 1H, 5-H), 4.27 (s, 2H, CH2), 3.87 (s, 3H,
OCH3), 3.38 (s, 3H, N CH3) ppm. Anal. Calcd.
for C19H17ClN2OS (356.87); C: 63.94; H: 4.80; N:
7.84; S: 8.98; found; C, 63.42; H, 4.77; N, 7.54; S,
8.95; HRMS calcd. for C19H17ClN2OS 356.87; found
356.07.
pyridazin-3-yl]thiourea 9e
To a solution of 3e (0.01) in ethanol (50 ml), thiourea
(0.01 mol) was added. The reaction mixture was
heated under reflux for 3 h and then cooled. The solid
product was collected by filtration and recrystallized
from benzene to give 2.2 g, 60% yield, mp 130–132 ◦C;
IR (KBr pellet): 3100–3250 (br) for (NH), 1630 (s)
for (C N), 1267–1274 (v) for (C S) cm−1; H NMR
1
(CDCl3, 200 MHz): δ 8.55 (s, 1H, NH), 8.36 (s, 2H,
NH), 7.16–7.92 (m, 8H, Ar-H), 6.76 (s, 1H, 5-H), 4.22
(s, 2H, CH2), 3.88 (s, 3H, OCH3), 2,63 (s, 3H, CH3)
ppm; Anal. calcd. for C20H20N4OS (364.46); C: 65.91;
H: 5.53; N: 15.37; S: 8.79; found: C, 66.20; H, 6.03; N,
14.90; S, 8.80; HRMS calcd. for C20H20N4OS 364.46;
found 364.13.
(3E)-4,6-Diarylpyridazin-3(2H)-one Hydrazones
8d–f
General Procedure F. A mixture of 4,6-diarylpy-
ridazin-3(2H)-thiones 3d–f (0.01 mol) and hydrazine
hydrate (0.01 mol) was heated for 3–5 h and then al-
lowed to cool at room temperature. The solid prod-
uct was collected by filtration and recrystallized from
benzene to give the title compounds.
4-(2-Methoxybenzyl)-6-methyl-2-(piperidin-1-
ylmethyl)pyridazine-3(2H)-thiones 10a
(3E)-4-(-2-Methoxybenzyl)-6-phenylpyridazin-
3(2H)-one Hydrazone 8d. Colourless crystals 1.85
g, 60% yield, mp 174–175◦C; IR (KBr pellet): 3100–
To a suspension of 3a,b (0.01 mol) in ethanol and
mixture of formaldehyde (30 ml, 0.015 mol), piperi-
dine (0.01 mol) was added dropwise. The reaction
mixture was heated under reflux for 3 h and then
cooled, and the solvent evaporated. The solid prod-
uct was collected by filtration and recrystallized from
ethanol for 10a to give 2.42 g, 70% yield, mp 162–
164◦C; IR (KBr pellet): 1625 (s) for (C N), 1267–
1275 (v) for (C S) cm−1; 1H NMR (CDCl3, 200 MHz):
δ 6.90–7.13 (m, 4H, Ar-H), 6.78 (s, 1H, 5-H), 4.98 (d,
1H, J = 15.2 Hz, N CH2), 4.24 (s, 2H, CH2), 3.87 (s,
3H, OCH3), 3.77 (d, 1H, J = 15.2 Hz, N CH2), 3.15–
3.47 (m, 6H, pip), 2.68 (s, 3H, 6-CH3), 1.42–1.47 (m,
4H, pip-) ppm; Anal. calcd. for C19H25N3OS (343.49);
C: 66.43; H: 7.33; N: 12.23; S: 9.33; found; C, 63.30; H,
1
3150 (br) for (NH), 1630 (s) for (C N) cm−1; H
NMR (CDCl3, 200 MHz): δ 8.78 (s, 1H, NH), 8.32 (s,
2H, NH), 7.15–7.90 (m, 9H, Ar-H), 6.73 (s, 1H, 5-H),
4.23 (s, 2H, CH2), 3.88 (s, 3H, OCH3) ppm; Anal.
calcd. for C18H18N4O (306.36); C: 70.56; H: 5.9219;
N: 18.28; found: C, 70.95; H, 5.40; N, 18.72; HRMS
calcd. for C18H18N4O (306.36); found 306.14.
(3E)-4-(2-Methoxybenzyl)-6-(4-methylphenyl)-
pyridazin-3(2H)-one Hydrazone 8e. Colourless
crystals 2.25 g, 70% yield, mp 165–166◦C; IR (KBr
pellet): 3100–3250 (br) for (NH), 1630 (s) for (C N)
cm−1; 1H NMR (CDCl3, 200 MHz): δ 8.67 (s, 1H,