Domino Construction of Benzoxazole-Derived Sulfonamides via Metal-Free Denitrogenation of 5‑Iodo-1,2,3-triazoles in the Presence of SO2 and Amines

A straightforward domino approach to assemble benzoxazole-derived sulfonamides has been developed. The method is based on annulation-induced in situ generation of diazo compounds from readily available 2-(5-iodo-1,2,3-triazolyl)­phenols, followed by metal-free denitrogenative transformation upon the action of 1,4-diazabicyclo[2.2.2]­octane bis­(sulfur dioxide) (DABSO) and amines. The protocol is operationally simple and features a broad substrate scope, furnishing a library of target compounds in generally good yields.