Embracing triplet nitrenes for C-to-N replacement of complex bicyclic (hetero)aryl azides.

Despite recent proof-of-concept advances, aromatic carbon-to-nitrogen replacement reactions remain substrate specific and exhibit an overreliance on harsh oxidation methods that preclude their deployment in demanding contexts. Transformations relying on singlet nitrene valence isomerization, in particular, have suffered from competitive intersystem crossing to the triplet spin state, which does not undergo the same rearrangement. In this work, we report a reaction that productively engages triplet aryl nitrenes for carbon-to-nitrogen replacement on the benzenoid ring of a range of bicyclic heteroarenes, including naphthalenes, anthracene, indoles, benzofurans, benzothiophene, indazoles, and benzisothiazoles. The reaction proceeds under mild conditions, which enables its application to complex, sensitive natural products.