Rhodium-Catalyzed Interconversion of Quinolinyl Ketones with Boronic Acids via C-C Bond Activation.

A rhodium-catalyzed cross-coupling of aryl and aliphatic quinolinyl ketones with boronic acids has been developed. Proceeding via quinoline-directed carbon-carbon σ bond activation, the transformation demonstrates tolerance of a range of functional groups on both the ketone and aryl boronic acid substrates, providing good to excellent yields of the new ketones, particularly those containing electron-withdrawing substituents. Catalyst reactivity is dependent on quinolinyl ketone substrates, with alkyl ketones requiring Rh(PPh3)3Cl instead of the more reactive [Rh(C2H4)2Cl]2. With the use of K2CO3 as an additive, methyl boronic acid is also a competent substrate, giving rise to an unprecedented methylation technique.