N‑Phenoxyamides as Multitasking Reagents: Base-Controlled Selective Construction of Benzofurans or Dihydrobenzofuro[2,3‑d]oxazoles

An efficient method to selectively construct benzofuran and dihydrobenzofuro­[2,3-d]­oxazole derivatives has been successfully established by means of base-controlled cyclization of N-phenoxyamides with 1-[(triisopropylsilyl)­ethynyl]-1,2-benziodoxol-3­(1H)-one (TIPS-EBX). N-phenoxyamides as multitasking reagents have triggered two different cascade reaction sequences. This is the first example of using TIPS-EBX for the transformation of C­(sp) to either C­(sp2) or C­(sp3) under metal-free conditions.