7-bromo-[1,2,4]triazolo[1,5-a]pyridin-2-amine

Application

7-Bromo-[1,2,4]triazolo[1,5-A]pyridine-2-amine is an organic intermediate that can be prepared by first preparing 1-ethoxycarbonyl-3-(4-bromo-pyridin-2-yl)-thiourea from 4-bromopyridine-2-amine and 4-bromopyridine-2-amine, and then reacting it with hydroxylamine hydrochloride to obtain 7-bromo-[1,2,4]triazolo[1,5-a]pyridine-2-amine.

Synthesis

1-Ethoxycarbonyl-3-(4-bromopyridin-2-yl)thiourea (17.5 g, 57.5 mmol) was mixed with hydroxylamine hydrochloride (20.0 g, 288 mmol) and N-ethyl diisopropylamine (30.1 ml, 173 mmol) in ethanol (367 ml). After stirring for a few minutes at room temperature, the reaction mixture was heated to reflux for 24 hours. After completion of the reaction, the solvent was removed by distillation under reduced pressure. Water (100 ml) was added to the residue and stirred for 10 min to form a suspension. The solid product was collected by filtration, washed with water and dried to give 7-bromo-[1,2,4]triazolo[1,5-a]pyridin-2-amine (10.71 g, 87.4% yield) as a light yellow solid. Melting point: 190-192°C. Mass spectrum (MS): m/z = 213.0, 215.0 ([M+H]+).

References

[1] Patent: WO2012/76430, 2012, A1. Location in patent: Page/Page column 90
[2] Patent: WO2006/38116, 2006, A2. Location in patent: Page/Page column 21
[3] Patent: WO2010/7100, 2010, A1. Location in patent: Page/Page column 40-41
[4] Patent: US2012/142665, 2012, A1. Location in patent: Page/Page column 17
[5] Patent: WO2010/20363, 2010, A1. Location in patent: Page/Page column 129