Regioselective C-H Alkylation via Carboxylate-Directed Hydroarylation in Water.

In the presence of catalytic [RuCl2 (p-cym)]2 and using Li3 PO4 as the base, benzoic acids react with olefins in water to afford the corresponding 2-alkylbenzoic acids in moderate to excellent yields. This C-H alkylation process is generally applicable to diversely substituted electron-rich and electron-deficient benzoic acids, along with α,β-unsaturated olefins including unprotected acrylic acid. The widely available carboxylate directing group can be removed or utilized for further derivatization. Mechanistic investigations revealed that the transformation proceeds via a ruthenacycle intermediate.