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

Automated summary

Copper catalysts containing ADAP ligand selectively functionalize unprotected indoles at the C3-H position through carbene transfer, without altering the N-H bond. Mechanistic studies, including DFT calculations, propose two competitive pathways that do not involve the formation of cyclopropane intermediates, contrasting with previous reports.