1150617-56-3

6-bromo-1-methyl-1H-pyrazolo[4,3-b]pyridine can be useful in the preparation, SAR and biological evaluation of (pyrimidinyl)-pyrazolo[4,3-b]pyridine derivatives as dual FLT3/CDK4 inhibitors.

To a solution of 6-bromo-1H-pyrazolo[4,3-b]pyridine (400 mg, 2.02 mmol) in N,N-dimethylformamide (DMF, 10 mL) was slowly added a mineral oil dispersion of 60% sodium hydride (NaH) (80.8 mg, 2.02 mmol) at 0 °C. The reaction mixture was stirred at room temperature for 30 min. Subsequently, a solution of iodomethane (MeI, 287 mg, 2.02 mmol) in DMF (5 mL) was added dropwise and stirring was continued for 30 minutes at room temperature. Upon completion of the reaction, the mixture was poured into water and extracted with ethyl acetate (EtOAc). The organic layers were combined, washed with saturated brine, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. Purification of the residue by preparative reversed-phase high performance liquid chromatography (HPLC) afforded the target compound 6-bromo-1-methyl-1H-pyrazolo[4,3-b]pyridine as a white solid (150 mg, 35% yield).1H NMR (300 MHz, DMSO-d6) δ 8.58-8.60 (m, 2H), 8.30-8.31 (m, 1H) 4.06 (s, 3H).

[1] Patent: WO2015/31613, 2015, A1. Location in patent: Paragraph 000176
[2] Patent: US2013/281433, 2013, A1. Location in patent: Paragraph 0854
[3] Patent: WO2016/57834, 2016, A1. Location in patent: Paragraph 000574