From C-F Activation to Catalytic Regioselective Double Hydrodefluorination of Pyridines with a Nickel Complex

The nickel(0) complex [Ni(iPrPN)(COD)] (iPrPN = 2-[(N-diisopropylphosphino)methylamino]pyridine, COD = 1,5-cyclooctadiene) has been found an efficient precatalyst for the hydrodefluorination of pyridines employing HBPin. Substituted 2,6-difluoropyridines were doubly hydrodefluorinated selectively at the 2 and 6 positions at room tem-perature employing 5 mol% of catalyst loading. Mechanistic studies for the hydrodefluorination of 2,6-difluoropyridine allowed to identify COD decoordination followed by C-F activation of the fluorinated pyridine as the catalyst entry pathway to the cycle and the [Ni(iPrPN)(COD)] complex as the catalyst resting-state.