Hydroxyamine hydrochloride → (5-Chloro-1H-indol-3-yl)methanamine

A solution of 5-chloro-1H-indole-3-carbaldehyde (0.690 g; 3.76 mmol), hydroxylamine hydrochloride (0.366 g; 5.27 mmol) and sodium acetate (0.463 g; 5.65 mmol) in ethanol (10 mL) was stirred at reflux for 3.5 h. The reaction mixture was concentrated under reduced pressure and the residue was partitioned between ethyl acetate and brine and extracted with ethyl acetate. The solvent was evaporated and the resulting residue (crude oxime) was dissolved in glacial acetic acid (30 mL). Zinc dust (1.48 g; 22.59 mmol) was added to the solution, and the mixture was stirred overnight at room temperature. The suspension was filtered through Celite, the cake was washed with ethyl acetate, and the organic solution was concentrated under reduced pressure. An aqueous solution of sodium carbonate was added to the residue and the resulting mixture was extracted with ethyl acetate. The organic extracts were dried over magnesium sulfate, filtered, and concentrated to afford the (5-chloro-1H-indol-3-yl)methanamine as a brown solid, which was used without further purification in the next step.