Site-Selective C-H Annulation Reaction via Thianthrenium Salts of Arenes

This work presents a site-selective C-H annulation strategy for dihydrobenzoisoxazole synthesis using readily accessible thianthrenium salts as aryne precursors. The process involves base-mediated generation of reactive aryne intermediates from thianthrenium salts followed by regioselective [3 + 2] cycloaddition with nitrone 1,3-dipoles, exhibiting excellent functional group tolerance and exceptional regiocontrol. The synthetic utility of this protocol is highlighted by the successful annulation of commercially available drug molecules, providing expedient access to novel scaffolds with potential bioactivity.