DFT Study Of The Mechanisms Of Fluorination With The Cycle Hypervalent Fluoroiodane Reagent And C-F Bond Activation By Organolithium Reagents

The demand for fluorine-containing compounds is rapidly growing as a result of their widespread applications in pharmaceutical,agrochemical,and materials industries.Consequently,enormous efforts have been devoted to the development of safe and efficient fluorinating reagents and selective synthetic methodologies for the introduction of fluorine into organic molecules.Recently,the air-and moisture stable cycle hypervalent fluoroiodane reagent has received special attention in the development of new fluorination reactions.However,it has remained poorly understood with regard to its fluorination mechanism.In addition to fluorination reaction,there has been increasing interest in the synthesis of partially substituted fluorocarbons through the activation of C-F bond with organolithium reagents.However,little is known about the details of the reaction mechanism.In this study,we have investigated the detailed mechanisms of fluorination with the cycle hypervalent fluoroiodane reagent and C-F bond activation by organolithium reagents with Density Functional Theory.The following conclusions have been obtained:(1)the calculations suggested an alternative mechanism for the fluorocyclization of o-styryl benzamide with the cyclic hypervalent fluoroiodane reagent.The new mechanism well rationalized the observed intriguing chemoselectivity;(2)In contrast to the popular electrophilic N-F reagent like Selectfluor,the F atom in the fluoroiodane reagent was revealed to be nucleophilic,and the I(III)atom is the most electrophilic site,thus inducing a completely different reactivity pattern;(3)The lithium ion was found to play an important role in the activation of C-F bond,which is in consistent with the experimental observation.