Thianthrenium and phenoxathiinium salts from arylborons mediated by copper

Guo, Wang, and co-workers recently presented in Journal of the American Chemical Society a copper-mediated thianthrenation and phenoxathiination of (hetero)arylborons. Importantly, this synthetic method provides access to a new untapped library of sulfonium salts with high efficiency and functional group tolerance. A telescoped synthesis is also realized via Ir-catalyzed C–H borylation followed by the Cu-mediated thianthrenation.