Direct Pd-Catalyzed Arylation of Triazoles

Significance

Reported here is a development of a highly efficient method for the synthesis of 5-aryl 1,2,3-triazoles via a direct Pd-catalyzed C-H coupling with aryl bromides. Introduction of both electron-rich and -deficient aryl groups was successfully executed. Similarly, regioselective C-5 arylation of N-substituted 1,2,3-triazoles with aryl bromides bearing EWGs and EDGs was efficiently achieved. On the other hand, in a limited study C-4 arylation of 1,5-disubstituted 1,2,3-triazoles was found to be very sluggish and produced only moderate yields.