1H-Pyrazolo[3,4-b]pyridine,3-methyl-(9CI)

55676-21-6

116834-96-9

Step 3: Synthesis of 3-methyl-1H-pyrazolo[3,4-b]pyridine 1-(2-chloropyridin-3-yl)ethanone (22 g, 0.1415 mol) was dissolved with 98% hydrazine hydrate (113 g, 2.21 mol) in ethanol (300 mL) and reacted at reflux for 12 hours. Upon completion of the reaction, about 80% of the ethanol was removed by distillation under reduced pressure using a rotary evaporator. The residue was cooled to room temperature and the precipitated solid was collected by filtration and washed with cold water. The resulting product was dried to constant weight at 90 °C to give 3-methyl-1H-pyrazolo[3,4-b]pyridine (16 g, 85% yield) with a melting point of 152-154 °C. 1H NMR (CDCl3) δ: 8.62 (dd, J = 4.5, 1.4 Hz, 1H), 8.08 (dd, J = 8.0, 1.4 Hz, 1H), 7.15 (dd, J = 8.0, 4.5 Hz, 1H), 2.64 (s, 3H). MS (FAB) m/z: 133 (M++1).