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M. I. Abdel Moneam
5,6-Dihydro-5-imino-7-(3-methyl-5-oxo-pyrazol-1-yl)-3,4,6-
triphenylpyrimido[4,5-c]pyridazine (12, C28H21N7O)
A mixture of 2 g of 6a (0.005mol) and 0.65g of ethyl acetoacetate (0.005mol) in ethanol (30 cm3) was
refluxed for 5 h. After cooling the solid product was filtered off and recrystallized from ethanol=CHCl3
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to give yellow crystals in 71% yield; mp >300ꢁC; IR: ꢀꢀ¼ 3100 (NH), 1670 (C¼O) cmꢃ1; H NMR
(DMSO-d6): ꢁ ¼ 2.1 (s, CH3), 4.5 (s, CH2), 7.5–8.9 (m, 15ArH), 9.3 (s, NH) ppm.
4,5-Dihydro-5-imino-4,6,7-triphenyl-s-triazolo[30,40:2,3]pyrimido[4,5-c]pyridazine-
1(2H)-thione (13, C25H17N7S)
A sample of 2 g of 6a (0.005 mol) and carbon disulphide (3cm3) in pyridine (20 cm3) was heated on a
water bath for 8 h, and then allowed to cool. The solid product was collected and recrystallized from
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dioxane to give yellow crystals in 65% yield; mp 255ꢁC; IR: ꢀꢀ¼ 3310 (NH), 1610 (C¼N) cmꢃ1; H
NMR (DMSO-d6): ꢁ ¼ 7.5–8.4 (m, 15ArH), 9.8, 10.3 (2s, 2NH) ppm.
5,6-Dihydro-5-imino-3,4,6-triphenyltetrazolo[50,10:2,3]pyrimido[4,5-c]pyridazine
(14, C24H16N8)
To a cooled sample of 0.5 g of 6a in glacial acetic acid (15 cm3), a cold solution of sodium nitrite (0.3g
in 5 cm3 of H2O) was added dropwise with stirring. Stirring was continued for 3 h at room temperature,
the solid product was filtered off, and recrystallized from dioxane to give pale brown crystals in 62%
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yield; mp 285ꢁC (decomposed); IR: ꢀꢀ¼ 3310 (NH), 1610 (C¼N) cmꢃ1; H NMR (CF3COOD):
ꢁ ¼ 7.3–7.8 (m, 15ArH) ppm. EI: m=z ¼ 416.5.
4,5-Dihydro-1-ethoxycarbonylmethylthio-5-imino-4,6,7-triphenyl-s-triazolo[30,40:2,3]-
pyrimido[4,5-c]pyridazine (15, C28H23N7O2S)
A mixture of 4.47g of 13 (0.01 mol), 1.5 g of ethyl chloroacetate (0.01 mol), and 0.98g of sodium
acetate (0.012mol) in 30cm3 of ethanol was heated under reflux for 4 h, and then allowed to cool. The
solid product was collected by filtration as white crystals in 77% yield; mp 193–192ꢁC; IR: ꢀꢀ¼ 3410
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(–NH), 1715 (C¼O) cmꢃ1; H NMR (CDCl3): ꢁ ¼ 1.5 (t, J ¼ 7.0 Hz, CH3), 4.2 (q, J ¼ 7.0 Hz, CH2),
4.7 (s, CH2), 7.3–8.1 (m, 15ArH), 9.7 (s, NH) ppm.
5,6-Dihydro-7-ethoxymethylenehydrazino-5-imino-3,4,6-triphenylpyrimido[4,5-c]-pyridazine
(16, C27H23N7O)
A mixture of 2 g of 6a (0.005 mol), triethyl orthoformate (3cm3), and 1 cm3 of glacial acetic acid was
heated under reflux for 3 h, and then cooled. The solid product was filtered off and recrystallized from
acetic acid to give pale yellow crystals in 64% yield; mp 185ꢁC; IR: ꢀꢀ¼ 3410, 3350 (NH), 2900 (CH
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aliphatic), 1590 (C¼N) cmꢃ1; H NMR (DMSO-d6): ꢁ ¼ 1.5 (t, J ¼ 7.0 Hz, CH3), 3.7 (q, J ¼ 7.0 Hz,
CH2), 7–7.5 (m, 15ArH), 11.1 (s, 2NH) ppm.
Ethyl [5,6-Dihydro-5-imino-3,4,6-triphenylpyrimido[4,5-c]pyridazine-7-yl]carbazate
(17, C27H23N7O2)
A mixture of 2 g of 6a (0.005 mol), ethyl chloroformate (10 cm3), and 2.0 cm3 of pyridine was refluxed
for 4 h, the excess ethyl chloroformate was removed by distillation and the solid product which formed
after adding ethanol was crystallized from dioxane to give pale yellow crystals in 71% yield; mp
173–175ꢁC; IR: ꢀꢀ¼ 3400, 3150 (NH), 1710 (C¼O), 1600 (C¼N) cmꢃ1; 1H NMR (DMSO-d6): ꢁ ¼ 1.3
(t, J ¼ 7.0 Hz, CH3), 4.1 (q, J ¼ 7.0 Hz, CH2), 7.3–8.1 (m, 15ArH) 10.5 (s, 2NH); 11.2 (s, NH) ppm.