Carboxylate-Directed Addition of Aromatic C–H Bond to Aromatic Aldehydes under Ruthenium Catalysis

We report that ruthenium complexes effectively catalyzed the carboxylate-directed addition of aromatic C–H bonds to aldehydes. The reactions of aromatic acids with a variety of aromatic aldehydes including unactivated ones proceeded efficiently to give the corresponding isobenzofuranone derivatives in high yields. The combination of ruthenium­(II) complexes with tricyclohexylphosphine led to highly nucleophilic aryl–metal species, which enabled versatile [3 + 2] cycloaddition in the absence of a Lewis acid. This paper also demonstrates the application of supported ruthenium catalysts to the title reaction