Potassium Carbonate → 6-(2,4-Difluorophenoxy)-3-iodo-4-methyl-1,4-dihydro-pyrazolo[4,3-b]pyridin-5-one

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Reaction Steps

To a solution of 6-(2,4-difluorophenoxy)-4-methyl-1-(2-trimethylsilanyl-ethoxymethyl)-1,4-dihydro-pyrazolo[4,3-b]pyridin-5-one (118 mg, 0.289 mmol) in chloroform (25 mL) was added iodine monochloride (141 mg, 3 eq) followed by potassium carbonate (200 mg, 5 eq) and the resulting mixture was heated under reflux with stirring (in the dark) for 24 hours. Additional iodine monochloride (large excess) was added and the resulting solution was stirred under reflux for another 16 hours. The reaction mixture was cooled to room temperature and diluted with dichloromethane, and washed 2× with an aqueous solution of Na2S2O3(aq) followed by brine. The organic layer was dried over magnesium sulfate, filtered and concentrated to give the crude product as an oil (97 mg). Purification by Preparative Thin Layer Chromatography eluting with 60% ethyl acetate in hexanes gave the title compound as an off-white powder (12 mg, (M+H)+=462).

Provenance & Evidence