3,3-Dibromo-1H-pyrrolo[2,3-b]pyridin-2(3H)-one → 1H-Pyrrolo[2,3-b]pyridine-2,3-dione 3-[O-(2-fluoro-ethyl)-oxime]

Participants

Reaction Steps

A solution of 3,3-dibromo 7-aza oxindole (300 mg, 1.03 mmol) in DMSO (25 mL) was heated at 95° C. under house vacuum for 6.5 hours. The solution containing the corresponding 7-aza isatin was cooled to room temperature, followed by the addition O-(2-fluoro-ethyl)-hydroxylamine hydrochloride (prepared as described by Ishikawa et al J. Antibiot., 2000, 53, 1071) (131 mg, 1.13 mmol). After stirring for 1 hour at room temperature the mixture was quenched with water and extracted with ethyl acetate (6×25 mL). The combined organic phases were washed with brine and dried over MgSO4. The solvent was removed in vacuo and the residue purified by flash column chromatography (gradient, 2% MeOH in methylene chloride to 3%) to give 1H-pyrrolo[2,3-b]pyridine-2,3-dione 3-[O-(2-fluoro-ethyl)-oxime] (200 mg, 93%) as an orange solid that was further purified by trituration from diethyl ether-DCM (1:1).

Provenance & Evidence