Base‐Free Selective O ‐Arylation and Sequential [3,3]‐Rearrangement of Amidoximes with Diaryliodonium Salts: Synthesis of 2‐Substituted Benzoxazoles

A variety of functionalized 2‐substituted benzoxazoles can be prepared in good yields from amidoximes and diaryliodonium salts by selective O ‐arylation and sequential [3,3]‐rearrangement under metal‐free conditions. O ‐arylation of amidoximes was promoted by 3 Å molecule sieves in the absence of a base and a sequential TFA‐mediated [3,3]‐rearrangement was used to synthesize 2‐substituted benzoxazoles. Both of the O ‐aryl products and rearrangement products were compatible with a broad range of sensitive functional groups such as ester, aldehyde, nitro, vinyl, amine, and amide groups in addition to halides. A bidentate N ‐ligand with double benzoxazoles was prepared at gram‐scale in two steps.