3-b]pyridine

94220-45-8

1357945-27-7

To a solution of 5-chloro-1H-pyrazolo[4,3-b]pyridine (XIII) (13 g, 84.7 mmol) in N,N-dimethylformamide (DMF) (100 mL) was added iodine (43.0 g, 169 mmol), followed by batchwise addition of potassium hydroxide powder (23.75 g, 423 mmol), and the reaction mixture was cooled in an ice water bath. The reaction mixture was stirred at 25 °C overnight. The solid potassium hydroxide was removed by filtration and the filter cake was washed with ethyl acetate (EtOAc). Most of the DMF was evaporated under reduced pressure and the residue was diluted with water (200 mL) and extracted with ethyl acetate (5 × 200 mL). The organic phases were combined, washed with saturated saline (500 mL) and dried over anhydrous sodium sulfate (Na2SO4). The organic phases were concentrated to afford 5-chloro-3-iodo-1H-pyrazolo[4,3-b]pyridine (XIV) as an orange solid (23.5 g, 84.1 mmol, 99.3% yield). The m/z of C6H3ClIN3 was measured to be 279.9 ([M+H]+) by electrospray ionization mass spectrometry (ESIMS).