Rapid α-amination of N-substituted indoles by using DBU-activated N -haloimides as nitrogen sources

Abstract

By using the N-haloimide/DBU protocol, the electrophilic imidation at C2-position of N - substituted indoles has been achieved in high efficiency. The dual activation of N-haloimide by DBU to simultaneously achieve a more electrophilic bromine and a more nucleophilic nitrogen atom, is demonstrated to be crucial in this transformation. The process involves tandem bromonium ion formation, electrophilic addition, and elimination of HBr. The protocol provides a novel, efficient, green, and complimentary access to α-imidated indoles under mild conditions, without the necessity of external nitrogen sources.