Rhodium‐Catalyzed Meta‐C‐H Arylation of Arenes with Varied Linker Lengths: Bridging Catalytic Selectivity with Structural Diversity

The directing group (DG)‐assisted approach has so far been the major route to achieve selective C‐H activation at both proximal and distal positions. While rhodium catalysts are highly effective in DG‐assisted ortho‐C‐H arylation, meta‐C‐H arylation with rhodium has not yet been reported. In this study, we present the first example of Rh‐catalyzed meta‐C‐H arylation of arenes. We found that the 2‐cyanophenyl‐based directing group, in conjunction with aryl boronic acids, selectively promotes meta‐arylation with complete mono‐selectivity. Despite significant advancements in meta‐C‐H activation for substrates with shorter linkers, such as hydrocinnamic acids, benzyl alcohols/amines, etc., meta‐C‐H activation of substrates with longer alkyl chains remains challenging with limited literature examples. We demonstrated that arenes with varying chain lengths, including conformationally flexible and less rigid ones such as 4‐phenylbutanoic acid, 5‐phenyl valeric acid, 6‐phenylcaproic acid, 3‐phenylpropanol, and 4‐phenylbutanol underwent meta‐arylation with high levels of regiocontrol. From a synthetic perspective, this approach could be valuable as it allows for the production of biaryl derivatives of flexible arenes with native functional groups at the meta‐position. The synthetic utility of this strategy is demonstrated through the total synthesis of CNBCA, a bioactive compound possessing promising potency against the SHP2 enzyme activity in vitro.