Hydrochloric Acid → 3-bromo-1-cyclopentyl-4-methoxy-4,5-dihydro-1H-pyrrolo[3,2-c]pyridine-7-carboxylic acid

To a solution of methyl 3-bromo-1-cyclopentyl-4-methoxy-4,5-dihydro-1H-pyrrolo[3,2-c]pyridine-7-carboxylate (874 mg) in methanol (8 mL) was added 1N aqueous sodium hydroxide solution (8 mL), and the mixture was stirred at room temperature for 3 hr. To the reaction mixture was added 1N hydrochloric acid at 0° C., and the precipitate was collected by filtration, and dried to give the title compound (894 mg).