Ammonium Chloride → Methyl 3-amino-4-((4-((tert-butoxycarbonyl)amino)phenyl)thio)benzoate

Participants

Reaction Steps

A suspension of 4-(4-tert-butoxycarbonylamino-phenylsulfanyl)-3-nitro-benzoic acid methyl ester (22.8 g, 56 mmol), Fe powder (16.4 g, 282 mmol) and NH4Cl (15.1 g, 282 mmol) in aqueous EtOH [prepared from EtOH (228 mL) and H2O (228 mL)] was gradually heated to reflux and gently refluxed for 2 hours. The reaction mixture was cooled to room temperature and filtered through celite pad. The filtrate was evaporated. The aqueous residue was portioned between AcOEt and H2O, made basic to pH 9 with K2CO3, and then filtered through celite pad. The organic layer was separated, washed with H2O and brine, dried over MgSO4 and evaporated. The oily residue was crystallized in the treatment with i-Pr2O (200 mL) and stirred at room temperature for 30 minutes. The resulting crystal was collected by filtration, washed with i-Pr2O and dried at 60° C. overnight under reduced pressure to give the title compound as colorless crystal (13.9 g, 66%).

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