Chemoselective Ruthenium-Catalyzed C–O Bond Activation: Orthogonality of Nickel- and Palladium-Catalyzed Reactions for the Synthesis of Polyaryl Fluorenones

Abstract

Ruthenium-catalyzed C–O bond activation/arylation of methoxy and O-carbamoyl-substituted fluorenones is reported. Established are new reactions of compound 1 (X = H) to aryl (2) and 1,8-diaryl (3) fluorenones. Orthogonal ruthenium-, palladium- and nickel-catalyzed reactions with Suzuki–Miyaura reactions to afford 1,4-diaryl (4) and 1,4,8-triaryl fluorenones (5) are also described. The ready availability of starting methoxy fluorenones by directed ortho and remote metalation tactics confers facility to the presented reactions which may find application in material science areas. DFT calculations have been performed to rationalize the lack of C–H bond reactivity in the ruthenium-catalyzed reaction.