Copper‐Catalyzed Olefination of 4‐CF3‐Substituted Cyclohexadienones Using Sulfonylmethyl Isocyanides: An Electrostatic Repulsion‐Controlled Regioselectivity Switch Strategy

Abstract A Cu(OTf) 2 ‐catalyzed olefination of cyclohexadienones was developed using sulfonylmethyl isocyanides. A CF 3 moiety at the 4‐position of cyclohexadienones was shown to exert a pronounced electrostatic repulsion effect to give the olefination products via a preferential [3+2] cycloaddition with the ketone moiety followed by a facile fragmentation of transient oxazoline intermediates. The current Cu(II)‐catalyzed olefination of 4‐CF 3 ‐substituted cyclohexadienones demonstrates the reaction dichotomy involving a CF 3 ‐controlled 1,2‐addition over a Van Leusen 1,4‐addition pathway through the electrostatic repulsion effect. magnified image