Approach to Vicinal <i>t</i>‑Boc-amino Dibromides via Catalytic Aminobromination of Nitrostyrenes without Using Chromatography and Recrystallization

A 1.0 mol % amount of K3PO4·3H2O was found to catalyze aminohalogenation reaction of nitrostyrenes with N,N-dibromo-tert-butylcarbamate (t-Boc-NBr2) in a dichloroethane system. Good to excellent yields and complete regioselectivity have been achieved by taking advantage of the GAP workup without using traditional purification techniques such as column chromatography and recrystallization. A new mechanism is proposed involving radical and ionic catalytic cycles and an intramolecular migration.