A Cooperative Rhodium/Secondary Phosphine Oxide [Rh/P(O)nBu2] Template for Catalytic Hydrodefluorination of Perfluoroarenes

A [Rh/P(O)nBu₂] template for catalytic hydrodefluorination of perfluoroarenes is presented. Aside from substrates with electron-withdrawing functionalities, the system showed a high tolerance for challenging electron-donating functionalities and heterocycles. Mechanistic studies and a density functional theory study have identified a rhodium(I) dihydride as a catalytic species and the critical role of phosphine oxide as a cooperative fragment.

Abstract

The selective activation of C−F bonds under mild reaction conditions remains an ongoing challenge of bond activation. Here, we present a cooperative [Rh/P(O)nBu₂] 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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