Iron(III) Chloride Mediated para‐Selective C‐H Functionalization: Access to C5‐Chloro and C5,C7‐Dichloro/Dianisyl Substituted 2‐Arylbenzoxazoles

Abstract

Iron(III) chloride mediated para-selective CÀ H chlorination and subsequent annulation of 2amidophenol to synthesize C5-and C5, C7-chlorinated benzoxazoles was developed. Further, the oxidative cross-dehydrogenative coupling of amidophenol with anisole by ferric chloride was explored to achieve the remotely anisylated benzoxazoles.

Iron(III)‐Mediated Nucleophilic Halogenation of Phenols Using an Amido Directing Group

“…For example, Sutherland and co‐workers reported the iron(III) triflimide catalyzed iodination [10] and chlorination [11] of arenes through S E Ar process. Very recently, Panda and co‐workers realized the Fe(III)‐mediated halogenations of phenols via radical pathways under thermal conditions, affording chlorinated 2‐arylbenzoxazoles (Scheme 1b) [12] . To the best of our knowledge, there is no report on Fe(III)‐mediated nucleophilic halogenations of electron‐rich phenols.…”

“…Very recently, Panda and co-workers realized the Fe(III)-mediated halogenations of phenols via radical pathways under thermal conditions, affording chlorinated 2-arylbenzoxazoles (Scheme 1b). [12] To the best of our knowledge, there is no report on Fe(III)-mediated nucleophilic halogenations of electron-rich phenols. Based on the oxidative dearomatization reactions [13] of phenolic compounds for meta-selective functionalization, [14] we report our discovery of the Fe(III)-mediated oxidative S N Ar reaction, featuring site-specific and stepwise halogenations of aminophenols (Scheme 1c).…”