Methanol → HCID 178499173, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of 5-bromo-1H-pyrazolo[3,4-b]pyridine-3-carboxylic acid (XVIII) (1.6 Kg, 6.6 mol) in anhydrous MeOH (32 L) was added H2SO4 (160 mL). The reaction was slowly heated to 70° C. and stirred for 20 hours. The solution was concentrated under vacuum to a volume of 1.6 L. The residue was partitioned between DCM (120 L) and aqueous 10% NaHCO3 (32 L). The organic phase was separated and washed with aqueous 25% NaCl (32 L), dried over Na2SO4 and concentrated to a volume of 4.8 L. The product was crystallized by charging the solution with 3×n-heptane (8 L) while concentrating the volume to 4.8 L after each addition of n-heptane. The solid was filtered and dried under vacuum at 50° C. to produce methyl 5-bromo-1H-pyrazolo[3,4-b]pyridine-3-carboxylate (XVII) (1.53 Kg, 6.0 mol, 80.6% purity, 90.4% assay yield). 1H NMR (DMSO-d6, 400 MHz) δ ppm 3.95 (s, 3H), 8.62 (d, J=2 Hz, 1H), 8.73 (d, J=2.4 Hz, 1H), 14.78 (brs, 1H); ESIMS found C8H6BrN3O2 m/z 256.0 (M+H).

Provenance & Evidence