Hydrochloric Acid → 8-Bromo-2-chloro-[1,2,4]triazolo[1,5-a]pyridine

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Reaction Steps

To a cooled, stirred suspension of 8-bromo-[1,2,4]triazolo[1,5-a]pyridin-2-ylamine (0.961 g, 4.51 mmol) and copper(II)chloride dihydrate (0.20 g, 1.2 mmol) in 12 M of hydrochloric acid (10.0 mL) at 5° C. was added dropwise a solution of sodium nitrite (0.37 g, 5.4 mmol) in water (2 mL). Gentle gas evolution was noted. The mixture was stirred for 30 minutes at 5° C. then at room temperature for 18 hours. The yellow mixture was diluted with water (80 mL) and the resulting precipitate was filtered, rinsed with water and dried in-the-air. 8-Bromo-2-chloro-[1,2,4]triazolo[1,5-a]pyridine was isolated as a pale yellow solid (0.947 g, 90%) and was used without further purification. 1H NMR (400 MHz, (D3C)2SO, δ, ppm): 8.98 (d, J=6.9 Hz, 1H), 8.10 (d, J=7.8 Hz, 1H), 7.22 (t, J=7.0 Hz, 1H). MS=232, 234, 236 (MH)+.

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