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

Abstract

AbstractA Cu(OTf)2‐catalyzed olefination of cyclohexadienones was developed using sulfonylmethyl isocyanides. A CF3 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‐CF3‐substituted cyclohexadienones demonstrates the reaction dichotomy involving a CF3‐controlled 1,2‐addition over a Van Leusen 1,4‐addition pathway through the electrostatic repulsion effect.magnified image