1,2-Dibromo-1,1,2,2-tetrafluoroethane → 7-Bromo-6-chloro-3-(2-fluorophenyl)-1,2,4-triazolo[4,3-b]pyridazine

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Reaction Steps

Tetrabutylammonium difluorotriphenylstannate (6.8 g, 10.8 mmol) was added to a suspension of 6-chloro-3-(2-fluorophenyl)-7-(trimethylsilyl)-1,2,4-triazolo[4,3-b]pyridazine (3.17 g, 9.88 mmol), prepared as in Example 25 Step c), and 1,2-dibromotetrafluoroethane (6.0 ml, 50 mmol) in anhydrous THF (75 ml) and-the mixture was stirred at room temperature under nitrogen for 18 h. The mixture was diluted with dichloromethane (100 ml), filtered and the filtrate was concentrated. Flash column chromatography on silica gel, eluting with 50-100% EtOAc-hexane, gave 7-bromo-6-chloro-3-(2-fluorophenyl)-1,2,4-triazolo[4,3-b]pyridazine (2.84 g, 88%) as an off-white solid; 1H NMR (360 MHz, CDCl3) δ 7.31 (1H, dd, J=10 and 10 Hz), 7.36 (1H, ddd, J=8, 8 and 1 Hz), 7.57-7.63 (1H, m), 7.87 (1H, ddd, J=7, 7 and 2 Hz), 8.49 (1H, s); MS (ES+) m/e 327/329/331 [MH]+.

Provenance & Evidence