Zinc-Catalyzed Dual C-X and C-H Borylation of Aryl Halides.

A zinc-catalyzed combined C-X and C-H borylation of aryl halides using B2 pin2 (pin=OCMe2 CMe2 O) to produce the corresponding 1,2-diborylarenes under mild conditions was developed. Catalytic C-H bond activation occurs ortho to the halide groups if such a site is available or meta to the halide if the ortho position is already substituted. This method thus represents a novel use of a group XII catalyst for C-H borylation. This transformation does not proceed via a free aryne intermediate, but a radical process seems to be involved.