Mechanism of Silver-Mediated Geminal Difluorination of Styrenes with a Fluoroiodane Reagent: Insights into Lewis-Acid-Activation Model

Fluorination mediated by the cyclic hypervalent fluoroiodane reagent (<b>1</b>) often requires an exogenous Lewis acid. The widely accepted Lewis-acid-activation model is that a given Lewis acid binds to the oxygen atom of <b>1</b> (O-coordination) to polarize the I–O bond. Computational studies of silver-mediated geminal difluorination of styrenes with <b>1</b> reveal a new “F-coordination” model that is energetically much preferred over the commonly accepted “O-coordination” model. The calculations rationalize the regioselective formation of the geminal difluorination product