N-Bromosuccinimide/1,8-Diazabicyclo[5.4.1]undec-7-ene Combination: β-Amination of Chalcones via a Tandem Bromoamination/Debromination Sequence.

A one-pot cascade transformation of chalcones into β-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 α-bromoketones. The whole process involves tandem bromoamination and debromination, which represents a unique example of preparing β-aminoketones by the reaction of chalcones with the NBS/DBU combination.