Ammonium Chloride → tert-Butyl 4-(4-amino-2-cyanophenyl)piperazine-1-carboxylate

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Reaction Steps

4-(2-Cyano-4-nitro-phenyl)-piperazine-1-carboxylic acid tert-butyl ester (587 mg, 1.77 mmol) was dissolved in methanol (50 mL) and to this solution was added ammonium chloride (945 mg, 17.66 mmol) and zinc (1155 mg, 17.66 mmol). The mixture was magnetically stirred for 3 hr and the mixture was filtered through a pad of celite. The solids were rinsed with methanol and the combined filtrate was concentrated to a yellow solid. This crude intermediate was dissolved in ethyl acetate (400 mL) and the resulting solution was washed with water (400 mL) and brine (200 mL). The organic layer was collected, dried over sodium sulfate, and concentrated to give 4-(4-amino-2-cyano-phenyl)-piperazine-1-carboxylic acid tert-butyl ester that was used in the next step without further purification.

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