An adaptive catalytic system that provides control over the nitroarene hydrogenation network to prepare a wide range of aniline and hydroxylamine derivatives is presented. This system takes advantage of a delicate interplay between a rhodium(III) center and a Lewis acidic borane introduced in the secondary coordination sphere of the metal. The high chemoselectivity of the catalyst in the presence of various potentially vulnerable functional groups and its readiness to be deployed at a preparative scale illustrate its practicality. Mechanistic studies and density functional theory (DFT) methods were used to shed light on the mode of functioning of the catalyst and elucidate the origin of adaptivity. The competition for interaction with boron between a solvent molecule and a substrate was found crucial for adaptivity. When operating in THF, the reduction network stops at the hydroxylamine platform, whereas the reaction can be directed to the aniline platform in toluene.
Twoc ooperative arms ……[ Rh/P(O)nBu 2 ]a re in the process of activating and breaking CÀFb onds to create CÀHbonds.Intheir Research Article (e202219127), Christophe WerlØ and co-workers developed amolecular template based on these design elements to improve the catalytic hydrodefluorination of perfluoroarenes across aw ide range of substrates.
The selective activation of CÀ F bonds under mild reaction conditions remains an ongoing challenge of bond activation. Here, we present a cooperative [Rh/ P(O)nBu 2 ] template for catalytic hydrodefluorination (HDF) of perfluoroarenes. In addition to substrates presenting electron-withdrawing functional groups, the system showed an exceedingly rare tolerance for electron-donating functionalities and heterocycles. The high chemoselectivity of the catalyst and its readiness to be deployed at a preparative scale illustrate its practicality. Empirical mechanistic studies and a density functional theory (DFT) study have identified a rhodium(I) dihydride complex as a catalytically relevant species and the determining role of phosphine oxide as a cooperative fragment. Altogether, we demonstrate that molecular templates based on these design elements can be assembled to create catalysts with increased reactivity for challenging bond activations.
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