Acetic Acid → 6-fluoro-7-iodo-1H-pyrazolo[4,3-b]pyridine

Participants

Reaction Conditions

Reaction Steps

6-Fluoro-7-iodo-1H-pyrazolo[4,3-b]pyridin-3-amine (250 mg) was combined with water (4 mL) and AcOH (6 mL) was heated to 40° C. until the solution became clear. The reaction mixture was then cooled to 0° C. and a solution of sodium nitrite (137 mg) in water (1 mL) was added dropwise over about 30 minutes. The reaction mixture was then warmed to room temperature, and stirred for 16 hours. The reaction mixture was again cooled to 0° C. and stirred for another 0.5 hour to give a solid which was collected by filtration, and washed with cold water. The solid were suspended in diluted HI (0.25 mL 50% HI diluted with water to 2.75 mL) and dimethoxyethane (6.5 mL) and the reaction mixture was heated to 80° C. for 3 hours, then cooled to room temperature, neutralized with Na2CO3 solution, and then extracted with ethyl acetate (60 mL). The organic layer was dried over anhydrous Na2SO4, filtered, and evaporated under reduced pressure to give a residue which was purified by silica gel chromatography eluting with petroleum ether-ethyl acetate (5:1) to afford the title compound (120 mg, 50.6% yield) as a light yellow solid. 1H-NMR (400 MHz, DMSO-d6) δ ppm 13.77 (s, 1H) 8.50 (s, 1H) 8.40 (s, 1H). MS [M+H] found 264.0.

Provenance & Evidence