Ethyl Bromide → 3-bromo-4-(1H-pyrrolo[2,3-b]pyridin-3-yl)-1H-pyrrole-2,5-dione

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Reaction Steps

A solution of ethylmagnesium bromide is prepared from magnesium (12.7 mmol) suspended in bromoethane (12.7 mmol) and dry tetrahydrofuran (5 ml). The solution is stirred for 1 hour at ambient temperature and then 7-azaindole (12.7 mmol), dissolved in 40 ml of anhydrous toluene, is added dropwise. After 1 hour 30 minutes' stirring at ambient temperature, a solution of 2,3-dibromomaleimide (3.53 mmol) in 40 ml of anhydrous toluene is added dropwise. After 20 minutes, 60 ml of dry dichloromethane are added, and then the reaction mixture is stirred for 75 hours at 40° C. and subsequently hydrolysed with a saturated aqueous ammonium chloride solution. The organic product is extracted with ethyl acetate, and then the combined organic phases are dried over magnesium sulphate and filtered. After removal of the solvent by evaporation, and purification of the residue by chromatography on silica gel (cyclohexane/ethyl acetate: 3/2), the expected product is isolated.

Provenance & Evidence