Phosphorus oxychloride → HCID 22756855, compound

Participants

Reaction Steps

39 g. of 2-methyl-6-phenyl-2H-pyrazolo[3,4-b]pyridin-4-ol (0.17 mol.) are refluxed in 195 ml. of phosphorus oxychloride for 90 minutes. The excess phosphorus oxychloride is removed in vacuo and the residue is poured onto ice. Concentrated aqueous ammonia is added under external cooling to adjust the mixture to pH 8-9. Stirring is continued for one additional hour. The collected 4-chloro-2-methyl-6-phenyl-2H-pyrazolo[3,4-b]pyridine is washed with water and dried at 70°, yield: 41 g. (100%); m.p. 177°-179°. Recrystallization from ethyl acetate gives a melting point of 189°-190°.

Provenance & Evidence