Weak O-Assistance Outcompeting Strong N,N-Bidentate Directing Groups in Copper Catalyzed C-H Chalcogenation

A copper-mediated C-H chalcogenation of triazoles has been achieved by weak coordination. The user-friendly protocol showed high functional-group tolerance and ample substrate scope, yielding fully substituted 1,2,3-triazoles with complete positional site-selectivity. The C-H selenylation could likewise be achieved by means of copper catalysis. Our findings highlight for the first time that weak O-coordination can outcompete the strong N,N-bidentate coordination mode in C-H functionalization technology.