Rhodium-Catalyzed PIII-Directed ortho-C-H Borylation of Arylphosphines

Transition-metal-mediated metalation of an aromatic C-H bond that is adjacent to a tertiary phosphine group in arylphosphines via a four-membered chelate ring was first discovered in 1968. Herein, we overcome a long-standing problem with the ortho-C-H activation of arylphosphines in a catalytic fashion. In particular, we developed a rhodium-catalyzed ortho-selective C-H borylation of various commercially available arylphosphines with B(2)pin(2) through P-III-chelation-assisted C-H activation. This discovery is suggestive of a generic platform that could enable the late-stage modification of readily accessible arylphosphines.