Selective C-H Bond Functionalization of Unprotected Indoles by Donor-Acceptor Carbene Insertion

Copper catalysts containing alkoxydiaminophosphine (ADAP) ligand catalyze the selective C3-H functionalization of unprotected indoles upon carbene transfer from donor-acceptor diazo compounds, the N-H bond remaining unaltered during the transformation. Mechanistic studies, including DFT calculations, allows proposing the existence of two competitive pathways, none of them occurring through the formation of cyclopropane intermediates, at variance with previously reported systems. image