Theoretical Advances on the Mechanism of Transition Metal-Catalyzed C-F Functionalization

Abstract

Organic fluorine chemistry has attracted considerable attention due to its unique character in the field of materials science, catalytic chemistry, medicine, fine chemicals and biochemistry, which majorly focus on the construction and cleavage of carbon-fluorine bonds. The transition metals are introduced to allow new possibilities for activating carbon-fluorine bonds and are gradually becoming an alternative way to synthesize numerous complex organics containing fluorine. In this review, the recent works on the theoretical mechanistic study for transition metals mediated carbon-fluorine bonds activation and cleavage are summarized. Meanwhile, the general modes of carbon-fluorine bonds activation have been concluded systematically, including the oxidative addition of carbon-fluorine bonds to transition metals, transition-metal-activated nucleophilic substitution, S N 2 type activation of carbon(sp 3 )-fluorine bonds and β-fluorine elimination, etc. The theoretical calculation shows that the reaction could be proceed by an oxidation addition mode, when the zero-valent nickel catalyst with strong reducibility is employed. However, if a zero-valent platinum catalyst is used, oxidation addition only occurs at extra activated carbon-fluorine bonds. In the reduction of polyfluorinated aromatic hydrocarbons by hydrogenated metal species, aromatic nucleophilic substitution between hydride and polyfluorinated aromatic hydrocarbons could occur to realize the activation of carbon-fluoride bonds. For carbon(sp 3 )-fluorine bonds, if "hard" Lewis base such as lithium or magnesium salt is employed, the carbon(sp 3 )-fluorine bonds can be activated via bimolecular nucleophilic substitution (S N 2). In addition, β-fluoride elimination is also frequently proposed in transition metal-catalyzed C-F functionalizations.