One-pot Sequential Direct C-H Bond Arylation of Azoles Catalyzed by [Pd(phen)2](PF6)2: Synthetic Methods for Triarylated Azoles

Synthetic methods for triarylated azoles containing three different aryl groups via one-pot sequential multiple C-H bond arylations are described. The one-pot sequential diarylation of C5-monoarylated azoles was achieved by the simple sequential addition of two different aryl iodides with a [Pd(phen)(2)]PF6 catalytic system. The one-pot triarylation of N-methylimidazole was achieved by the combination of a previously reported Pd(OAc)(2)-P(2-furyl)(3) system and the present [Pd(phen)(2)]PF6 system. In this case, portionwise addition of aryl halide, base and the catalyst in the final step significantly improved the overall yield of the desired triarylated product These protocols led to triarylated azoles without a loss of efficiency compared to the corresponding previously reported stepwise syntheses via direct C-H bond arylation.