Exhaustive tert-butoxycarbonylation of Boc2NH with Boc2O-DMAP furnishes Boc3N in nearly quantitative yield. This stable compound is susceptible to nucleophiles and affords Boc2NH upon aminolysis. The properties of Boc3N have been exploited in a practical one-pot procedure for the synthesis of Boc2NH from NH4Cl, which is particularly economical in the preparation of (Boc2NH)-N-15.