Lewis Acid Promoted Vicinal Oxytrifluoromethylselenolation of Alkenes.

Herein, we have developed a metal-free, Lewis acid promoted vicinal oxytrifluoromethylselenolation of alkenes using trifluoromethyl selenoxides as electrophilic trifluoromethylselenolation reagents and alcohols as nucleophiles. With less steric and good nucleophilic solvents (such as ethanol and methol), TfO-catalyzed oxytrifluoromethylselenolation could be realized, while stoichiometric TfO was required to promote full transformation with less nucleophilic and steric solvents (such as isopropanol and -butanol). The reaction featured good substrate scope, functional group compatibility, and diastereoselectivity. This method could be further applied to oxytrifluoromethylselenolation, aminotrifluoromethylselenolation with stoichiometric nucleophiles under modified conditions. A mechanism involving a seleniranium ion was proposed based on the preliminary results.