反应详情

7-Chloro-3H-imidazo[4,5-b]pyridine-4-oxide (15 g, 88.5 mMol) and 300 mL phosphorus oxychloride were heated at 110° C. under a nitrogen atmosphere. After 4 hours the excess phosphorus oxychloride was removed in vacuo. The residue was dissolved in water and the solution was neutralized by the addition of aqueous ammonium hydroxide. The suspension was cooled and the solid isolated. After drying, the product, 5,7-dichloro-3H-imidazo[4,5-b]pyridine, weighed 10.5 g (54.5 mMol, 61.6%); m.p. 263° C.; NMR (DMSO-d6): 8.58 δ (s, 1H, H2); 7.58 (s, 1H, H5).

1. customAfter 4 hours the excess phosphorus oxychloride was removed in vacuo
2. dissolutionThe residue was dissolved in water
3. additionthe solution was neutralized by the addition of aqueous ammonium hydroxide
4. temperatureThe suspension was cooled
5. customthe solid isolated
6. customAfter drying