Dimethylformamide → 6-Chloro-1,3-dimethyl-1H-pyrazolo[3,4-b]pyridine-5-carbaldehyde

Participants

Reaction Conditions

Reaction Steps

A mixture of acetic anhydride (6.62 mL, 70 mmol) and 2,5-dimethyl-2H-pyrazol-3-ylamine (5.0 g, 45 mmol) was heated while stirring at 90-100° C. for 4 h. After evaporation of volatiles in vacuo, phosphorus oxychloride (18.5 mL, 200 mmol) was added and the mixture was heated while stirring at 90-95° C. for 3 h. Thereafter, anhydrous DMF (9.2 mL, 120 mmol) was added slowly over the period of 30 min while maintaining the internal temperature of the mixture at 90-95° C. After stirring for an additional 2 h, the reaction mixture was cooled to RT and poured over crushed ice (100-120 g). The precipitated solid was filtered off, washed with water and dried in vacuo. The yellowish solid product was subsequently dissolved in methylene chloride (100 mL), washed with water, dried over sodium sulfate, and the solvent was evaporated in vacuo to give the desired product as light yellow solid (4.1 g), yield: 44%, mp: 152-153° C.

Provenance & Evidence