The diverse synthetic processes afforded by reactive C–B bonds make C–H borylation reactions valuable for a number of applications. It is known that borylation of benzene or its derivatives can be achieved using an iridium catalyst and is a sterically-controlled reaction favoring meta and para borylation. Additional ortho C–H borylation methods have also been reported using various directing groups, including that of a benzylic amine developed by the Clark group. A mechanistic study of this or other directed C–H borylation reactions has not previously been reported; doing so would be important for the improvement of design methods and efficiency of the reaction, as well as for generalization of the reaction for its application in other conditions. This study determines the rate law of the ortho C–H borylation reaction as rate=k[substrate]1[B2pin2]1[[Ir(COD)OMe]2]1, with the iridium catalyst and substrate showing saturation kinetics. In conjunction with a Hammett study and a kinetic isotope effect study, a detailed mechanistic picture for this transformation will be discussed.

Mechanistic studies of the iridium-catalyzed ortho C–H borylation of benzylic amines

2019 Spring National Meeting

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