p-Toluenesulfonic acid → 6-Chloro-3-phenyl-7-(4-pyridinyl)-1,2,4-triazolo[4,3-b]pyridazine

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Reaction Steps

A mixture of 3,6-dichloro-4-(pyridin-4-yl)pyridazine (390 mg, 1.7 mmol), benzoyl hydrazine (260 mg, 1.9 mmol), triethylamine (270 ml, 1.9 mmol) and p-toluenesulphonic acid (32 mg, 0.2 mmol) in xylene (mixture of isomers) (5 ml) was stirred and heated at reflux under nitrogen for 20 hours. The mixture was partitioned between dichloromethane and saturated aqueous potassium carbonate. The aqueous was further extracted with dichloromethane (×3). The combined extracts were dried (sodium sulphate), filtered and evaporated. The residue was purified by chromatography on silica gel eluting with 3% methanol/dichloromethane to afford the title compound (218 mg, 42%) as a pale yellow solid. 1H NMR (360 MHz, d6-DMSO) δ 7.60-7.69 (5H, m), 8.36-8.38 (2H, m), 8.72 (1H, s), 8.78-8.80 (2H, m). MS (ES+) m/e 308 [MH]+, 310 [MH]+.

Provenance & Evidence