Ammonium Chloride → 5-amino-3-(N-t-butoxycarbonyl-1,2,5,6-tetrahydropyrid-4-yl)-1H-indole

To a solution of 7.4 mL dioxane, 5.5 mL ethanol and 3.7 mL distilled water was added tert-butyl 4-(5-nitro-1H-indol-3-yl)-5,6-dihydropyridine-1(2H)-carboxylate (184 mg, 0.54 mmol). To the mixture was added powdered iron (0) (0.15 g, 5.0 eq) and ammonium chloride (0.885 g, 4.0 eq). The reaction was heated to 70° C. under argon for 3 h. The reaction was cooled and filtered and washed with MeOH. The solvent was removed to obtain the crude which was purified by silica gel chromatography to afford the desired compound tert-butyl 4-(5-amino-1H-indol-3-yl)-5,6-dihydropyridine-1(2H)-carboxylate.