1H-Pyrrolo(2,3-b)pyridine → 3-Bromo-1H-pyrrolo[2,3-b]pyridine

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Reaction Steps

To a solution of 7-azaindole (5 g, 42.2 mmol) in THF (400 mL) were added first the solid N-bromosuccinimide (8 g, 45.0 mmol) then 20 drops of conc. sulfuric acid at room temperature. While stirring some suspension was formed during 2 days. The mixture was diluted with saturated ammonium chloride solution and the two layers were separated. The aqueous layer was extracted with ethyl acetate (4×150 mL). The combined organic extracts were washed with brine solution and dried over anhydrous magnesium sulfate. Filtration of the drying agent and removal of the solvent under the vacuum gave the crude yellow solid. This solid was dissolved in ethyl acetate (˜100 mL) at hot condition and then stored in the refrigerator overnight. The solids were collected by filtration and washed with ethyl acetate. After drying in air, 6.2 g (75% yield) of 3-bromo-1H-pyrrolo[2,3-b]pyridine was isolated as an yellow solid: EI-HRMS m/e calcd for C7H5BrN2 (M+) 195.9636. found 195.9636.

Provenance & Evidence