Photoexcited Nitroarenes: A Workhorse for Strategic Synthesis of N-Heterocycles via Reductive C-N...

Owing to their distinct electron-withdrawing properties, a combined nitro-assisted functionalization followed by tandem nitro group manipulation is emerging to streamline pharmaceutical synthesis. Herein, we disclose an expedient protocol for the synthesis of N-heterocycles, such as N-aryl indole, oxindole, benzoxazinone, and (tetrahydro)quinolinone, from photoexcited o-tethered nitroarenes at ambient temperature through a tandem C-N coupling/intramolecular cyclization. A nitrene intermediate is formed to furnish intermolecular C-N coupling with boronic acids, followed by intramolecular cyclization with pendant functional groups in a single operation. This metal-free, cascade annulation reaction is scalable and has been applied to the synthesis of APIs and drugs.