Conformation-Guided Remote C-H Functionalization of Aromatic Compounds.

Achieving site-selective C-H functionalization at remote, unbiased positions of the aromatic ring remains a major challenge in the field. We report a conformational control strategy that enables remote meta-selective C-H borylation of mono- and 1,2-disubstituted (poly)arenes via arene π-complexation with Cr(CO)3. The chromium tripod adopts a preferred conformation, exposing the meta-C-H bond, while a tailored iridium catalyst bearing 2-aminophenanthroline ligands reinforces this effect and overrides intrinsic substrate bias. In polyaromatics, the chromium tripod acts as both a conformational director and an electronic modulator, enabling site- and ring-selectivity, which is inaccessible with existing nondirected methods. Computational studies at a state-of-the-art DFT theoretical level support a cooperative origin of selectivity arising from the interplay between arene π-complexation and the catalyst.