Nitrenes are high-energy intermediates that enable challenging transformations such as C-H insertion, de-aromatization and rearrangement processes. Yet, nitrenes often exhibit poor chemoselectivity profiles. As a result, nitrene or nitrenoid-mediated processes typically employ stabilizing groups, such as carbonyl and sulfonyl substituents, or transition metals, in order to promote one desired reaction pathway. In the Williams lab, we are exploring boron and phosphorus(III) as stabilizing agents which can electronically alter the behavior of nitrenes. Our studies have resulted in an unusual synthesis of anilines arising from a borylnitrene C-H insertion and/or rearrangement. Experiments show complete selectively for nitrene insertion into aryl C-H bonds, with no reaction at the expected benzylic position. Further, a change of the spectator ligand on the boron center from an chloride to an alkoxide causes a chemoselectivity switch from an apparent intramolecular rearrangement to an intermolecular functionalization.

Inter- and intramolecular aryl insertion reactions of borylnitrenes

255th National Meeting (2018)

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