Preparation method of 7-bromo-[1,2,4]triazolo[1,5-A]pyridin-2-amine_Industrial additives

Background and overview of the preparation method of 7-bromo-[1,2,4]triazolo[1,5-A]pyridin-2-amine

7-Bromo-[1,2,4]triazolo[1,5-A]pyridin-2-amine is a sodium carbonate organic intermediate, which can be synthesized from 4-bromopyridin-2-amine and 4-bromopyridin-2-amine. ‑Bromopyridin‑2‑amine is used as raw material to prepare 1‑ethoxycarbonyl‑3‑(4‑bromo‑pyridin‑2‑yl)‑thiourea, and then react with hydroxylamine hydrochloride to obtain 7‑bromo‑[1,2, 4]Triazolo[1,5‑a]pyridin‑2‑amine.

Preparation method of 7-bromo-[1,2,4]triazolo[1,5-A]pyridin-2-amine

Preparation method of 7-bromo-[1,2,4]triazolo[1,5-A]pyridin-2-amine a) 1-ethoxycarbonyl-3-(4- Bromo-pyridin-2-yl)-thiourea

To a solution of 4-bromopyridin-2-amine (10.4g, 60.1mmol) in dioxane (242ml) was added ethoxycarbonylisothiocyanate (7.88g, 6.8ml, 60.1 mmol). The resulting mixture was stirred at 25°C for 4 hours. The solvent was evaporated and the solid yellow residue was diluted with ethyl acetate and washed with water and brine. The organic layer was separated, dried over magnesium sulfate, and the solvent was removed in vacuo to give 1-ethoxycarbonyl-3-(4-bromo-pyridin-2-yl)-thiourea as a yellow solid (17.37 g, 95% ). Melting point: 107-110℃. Mass spectrum: m/z=304.0, 305.9 (M+H+).

Preparation method of 7-bromo-[1,2,4]triazolo[1,5-A]pyridin-2-amine b) 7-bromo-[1,2,4]tri Azolo[1,5‑a]pyridin‑2‑amine

A mixture of hydroxylamine hydrochloride (20.7g, 298mmol) and N-ethyldiisopropylamine (23.1g, 31.2ml, 179mmol) in ethanol (380ml) was stirred at 25°C for a few minutes. Subsequently, this mixture was added to 1-ethoxycarbonyl-3-(4-bromo-pyridin-2-yl)-thiourea (18.13 g, 59.6 mmol), and the resulting mixture was refluxed for 1 day. The solvent was evaporated to dryness and the residue was triturated with water (100 ml) for 10 minutes. The solid was collected by filtration, washed with water, and dried to give 7-bromo-[1,2,4]triazolo[1,5-a]pyridin-2-amine as a pale yellow solid (10 g, 78.8%). Melting point: 190-2℃. Mass spectrum: m/z=212.9, 215.0 (M+H+).

References

[1] [Invented in China, authorized by China Invented Ferrocene Boric Acid] CN201180057674.X triazolopyridine compound