Mixing O-Containing and N-Containing Directing Groups for C-H Activation: A Strategy for the Synthesis of Highly Functionalized 2,2 '-Biaryls

A strategy combining O- and N-containing directing groups has been developed for the synthesis of 2,2'-biaryl via Pd-mediated C-H bond activation and oxidative coupling. This new transformation may proceed through a mechanism involving Pd(II) and Pd(IV) intermediates. We found the use of PTSA and HFIP to be critical for the reaction and suggest that these reagents could serve as efficient ligands for this C-C bond formation. This methodology provides broad functional group tolerance, excellent reactivity, and high yields.