Sodium Nitrite → 7-iodo-1H-pyrazolo[4,3-b]pyridine

Participants

Reaction Steps

To a suspension of 7-iodo-1H-pyrazolo[4,3-b]pyridin-3-amine (23 g) in water (90 mL) and AcOH (75 mL) was added dropwise a solution of sodium nitrite (12.6 g) in water (90 mL) over 30 minutes at 0° C. The mixture was warmed to room temperature and stirred for 24 hours. Then the mixture was cooled to 0° C. again and stirred for another 0.5 hour to give a solid which was collected by filtration and washed with cold water. The solid was suspended in aqueous HI (20 mL 50% HI diluted to 300 mL with water) and dimethoxymethane (600 mL). This mixture was heated to 80° C. for 3 hours, then cooled to room temperature, neutralized with Na2CO3 solution, and then extracted with ethyl acetate. The organic layer was collected, dried over anhydrous Na2SO4, filtered, and evaporated under reduced pressure to give a residue. This residue was purified by column chromatography eluting with 1:2 petroleum ether:ethyl acetate to afford the title compound as a light yellow solid (7.8 g). 1H-NMR (400 MHz, DMSO-d6) 7.86 (d, J=4.4 Hz, 1H) 8.16 (d, J=4.4 Hz, 1H) 8.46 (s, 1H) 13.67 (s, 1H).

Provenance & Evidence