Photoinduced hydrofluoroalkylation of alkenes

Hydrofluoroalkylation of alkenes is a valuable process for the synthesis of organofluorine compounds by attaching a fluorinated fragment and a hydrogen atom to a double bond. With the advent of photocatalysis, general interest in the hydrofluoroalkylation reaction has increased significantly, leading to the development of new conditions and an expansion of the range of competent reaction components. This review summarizes hydrofluoroalkylation methods, which are performed under photocatalytic conditions using visible light irradiation. The focus is on the mechanistic analysis of individual steps, including a detailed discussion on methods for generating fluorinated radicals and methods of trapping nascent radicals with a hydrogen source. Precursors of radicals working under the reductive or oxidative conditions, as well as process of the halogen atom transfer, are discussed. For the termination step, processes proceeding either via direct hydrogen atom transfer or via radical polar cross-over, which are operative depending on the nature of the alkene, are considered.