反应详情

Scheme 4 depicts the synthesis of the 1H-pyrazolo[3,4-b]pyridine q. A nicotinoylchloride k (e.g., 2-chloronicotinoyl chloride) is reacted with a hydrazine m (e.g., phenylhydrazine) and a base such as triethylamine in a solvent such as anhydrous methylene chloride to give o (e.g., 1-phenyl-1H-pyrazolo[3,4-b]pyridin-3-ol). The compound o is then cyclized by heating at 175° C. to provide p. p is reacted as in the transformation of d to g in Scheme 1 to provide q.