Cl[C:2]1[CH:7]=[C:6]([Cl:8])[N:5]=[N:4][C:3]=1[C:9]([O:11][CH3:12])=[O:10].[Cl:13][C:14]1[CH:15]=[CH:16][C:17]([NH2:21])=[N:18][C:19]=1[CH3:20]>C(#N)C>[Cl:8][C:6]1[N:5]=[N:4][C:3]([C:9]([O:11][CH3:12])=[O:10])=[C:2]([NH:21][C:17]2[CH:16]=[CH:15][C:14]([Cl:13])=[C:19]([CH3:20])[N:18]=2)[CH:7]=1A pressure tube was charged with methyl 4,6-dichloropyridazine-3-carboxylate (2 g, 9.66 mmol) and 5-chloro-6-methylpyridin-2-amine (2.76 g, 19.3 mmol). To the mixture was added acetonitrile (12 mL) and the reaction mixture heated with stirring at 130° C. for 1.5 days. After cooling to room temperature, the acetonitrile was removed in vacuo. The residue obtained was purified by chromatography (silica, 80 g, 50 μm from Analogix, 0% to 5% acetone in dichloromethane over 20 min., holding at 5% for 5 min, then increasing the gradient from 5% to 10% over the next 20 min) to give methyl 6-chloro-4-(5-chloro-6-methylpyridin-2-ylamino)pyridazine-3-carboxylate (618 mg, 20%) as an orange solid. 1H NMR (400 MHz, CHLOROFORM-d) δ ppm 10.70 (br. s., 1H), 9.18 (s, 1H), 7.63 (d, J=8.34 Hz, 1H), 6.78 (d, J=8.34 Hz, 1H), 4.12 (s, 3H), 2.66 (s, 3H), 1.58 (br. s., 1H); LC-MS 313 [M+H]+.
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