Fluorination and Fluoroalkylation Reactions Mediated by Hypervalent Iodine Reagents

This review summarizes the progress in the fluorination and fluoroalkylation of electron-rich systems with diverse fluorine (F) and fluoroalkyl (R-fn) reagents employing hypervalent iodine compounds as initiators in the last few decades. Because of the strong electrophilicity, high oxidizing properties, low toxicity, air and moisture stability, ready availability, ease of handling, and mild reaction conditions, the hypervalent iodine reagents have been widely utilized in modern organic chemistry. In particular, the use of hypervalent iodine reagents to initiate the C-F and C-R-fn(R-fn=CF2H, CF3, perfluoroalkyl, OCH2CF3, SCF3, SeCF3 and etc) bond formation has been increasingly developed. In these reactions, hypervalent iodine compounds behave as powerful oxidants or electrophiles and activate the fluorination/fluoroalkylation reagents, the transition-metal catalysts, or the substrates toin situform electrophilic or radical intermediates, which subsequently participate in fluorination, difluoromethylation, trifluoromethylation, perfluoroalkylation, trifluoroethoxylation, fluoroalkylthiolation, trifluoromethylselenolation and others under mild conditions. Although great achievements have been made in this area, they are just the initial phase and still require a wide scope for improvement. It is anticipated that this review will draw much attention from the organic chemistry community and inspire more contributions in the development of new hypervalent-iodine-mediated fluorination and fluoroalkylation reactions.