Aryl triflates: useful coupling partners for the direct arylation of heteroaryl derivatives via Pd-catalyzed C–H activation–functionalization

Abstract

Aryl triflates were found to be suitable partners for the palladium catalyzed direct arylation of heteroaromatics via C–H activation–functionalization. The reaction conditions and the catalyst have a determining influence on the yields. The system combining PPh₃ and Pd(OAc)₂ using KOAc as base and DMF as solvent promotes the selective 2- or 5-arylations in moderate to high yields. Several heteroaromatics such as furan, thiophene, thiazole or oxazole derivatives have been employed successfully. The electronic properties of the aryl triflates also have a decisive influence on the yields of the coupling products. Electron-rich aryl triflates gave satisfactory results, whereas the electron-poor ones led to the formation of phenols.