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

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).

1. temperatureThen the mixture was cooled to 0° C. again
2. stirringstirred for another 0.5 hour
3. customto give a solid which
4. filtrationwas collected by filtration
5. washwashed with cold water
6. temperatureThis mixture was heated to 80° C. for 3 hours
7. temperaturecooled to room temperature
8. extractionextracted with ethyl acetate
9. customThe organic layer was collected
10. dry with materialdried over anhydrous Na2SO4
11. filtrationfiltered
12. customevaporated under reduced pressure
13. customto give a residue
14. customThis residue was purified by column chromatography
15. washeluting with 1:2 petroleum ether

ORD record

ord-c83f6ff075754e0fb2142104ca38f7ee

Source dataset

uspto-grants-2015_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09073918B2