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

• Published in: Advanced synthesis & catalysis Vol. 359; no. 23; pp. 4129 - 4135
• Main Authors: Shi, Wei‐Min, Li, Xiao‐Hua, Liang, Cui, Mo, Dong‐Liang
• Format: Journal Article
• Language: English
• Published: WEINHEIM Wiley 11.12.2017; Wiley Subscription Services, Inc
• Subjects: [3,3]-Rearrangement; Amidoxime; Aromatic compounds; Benzoxazoles; Chemistry; Chemistry, Applied; Chemistry, Organic; Diaryliodonium salts; Functional groups; Halides; O-Arylation; Physical Sciences; Science & Technology; Substitutes; 2-ARYLBENZOXAZOLES; COPPER; C-H FUNCTIONALIZATION; Benzoxazoles; ELECTROCHEMICAL SYNTHESIS; [3,3]-Rearrangement; Amidoxime; AEROBIC OXIDATION; ARYL; Diaryliodonium salts; N-ARYLATION; PARALLEL SYNTHESIS; FACILE PREPARATION; BENZOTHIAZOLES; O-Arylation
• ISSN: 1615-4150; 1615-4169
• DOI: 10.1002/adsc.201700906

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.