C-H and C-F bond activation of fluorinated propenes at Rh: enabling cross-coupling reactions with outer-sphere C-C coupling

The reaction of [Rh{(E)-CF 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 CHCF3}(PEt3)3] with Zn(CH3)2 results in the methylation of the alkenyl ligand to give [Rh{(E/Z)-C(CH3)CHCF3}(PEt3)3]. Variable temperature NMR studies allowed the identification of a heterobinuclear rhodium-zinc complex as an intermediate, for which the structure [Rh(CH3)(ZnCH3){(Z)-C(CH3)CHCF3}(PEt3)2] is proposed. Based on these stoichiometric reactions, unique Negishi-type catalytic cross-coupling reactions of fluorinated propenes by consecutive C-H and C-F bond activation steps at room temperature were developed. The C-H bond activation steps provide a fluorinated ligand at Rh and deliver the fluorinated product, whereas the C-F bond activation and C-C coupling occur via outer-sphere nucleophilic attack at the fluorinated alkenyl ligand. Cross coupling reactions of fluorinated olefins occur by C-H bond activation at Rh to provide a fluorinated ligand for a subsequent outer-sphere C-F bond functionalization.