Synthesis of Dibenzofurans via Palladium-Catalyzed Phenol-Directed C–H Activation/C–O Cyclization

A practical, Pd(0)/Pd(II)-catalyzed reaction was developed for phenol-directed C–H activation/C–O cyclization using air as an oxidant. The turnover-limiting step of the process was found to be C–O reductive elimination instead of C–H activation. This reaction can tolerate a variety of functional groups and is complementary to the previous methods for the synthesis of substituted dibenzofurans.