A one-pot cascade transformation of chalcones into beta-imidoketones has been developed, in which NBS provides both electrophilic bromine and nucleophilic nitrogen sources, and DBU functions as a nucleophilic reagent to activate NBS to be a more electrophilic bromine species and to further remove the bromine of alpha-bromoketones. The whole process involves tandem bromoamination and debromination, which represents a unique example of preparing beta-aminoketones by the reaction of chalcones with the NBS/DBU combination.