N-methyl-2-pyrrolidone → Potassium Hydroxide

Participants

Reaction Steps

To a 1 L flask was charged 3,5-dibromopyridine-4-carboxaldehyde (50.0 g, 188.7 mmol, 1.0 eq) and 4-fluorophenylhydrazine hydrochloride (31.0 g, 190.7 mmol, 1.01 eq). NMP (250 mL) was charged, and the resulting slurry was stirred at ambient temperature for 2 hours. A solution of aqueous KOH was prepared from 85% KOH pellets (27.4 g, 415.2 mmol, 2.2 eq) and water (27.4 mL), and this KOH solution was charged to the reaction mixture. The batch was heated to 80° C. and held at this temperature for 30-60 minutes. Water (250 mL) was then charged at 80° C., and the resulting slurry was cooled to ambient temperature over 4-16 hours. The slurry was filtered, the solid was washed with water, and oven dried under vacuum to afford 4-bromo-1-(4-fluorophenyl)-1H-pyrazolo[3,4-c]pyridine as a tan colored solid, 51.5 g, 99.3 area % purity by HPLC, 93% yield.

Provenance & Evidence