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.