Ammonium formate → Ethyl 5-hydroxy-1-methyl-1H-indole-2-carboxylate

A mixture of crude ethyl 5-(benzyloxy)-1-methyl-1H-indole-2-carboxylate (1.07 g, 3.46 mmol), 10% palladium on carbon (500 mg, 0.47 mmol) and ammonium formate (1.09 g, 17.29 mmol) in 50 mL ethanol was sparged with argon three times and heated at reflux for 1 h. The mixture was cooled, diluted with 100 mL ethanol and filtered through Celite, washed with ethanol and concentrated to give ethyl 5-hydroxy-1-methyl-1H-indole-2-carboxylate (1.82 g, 49% over two steps).