(C 6 F 5 ) 3 B Catalyzed Chemoselective and ortho ‐Selective Substitution of Phenols with α‐Aryl α‐Diazoesters

The development of an efficient method for the site‐selective substitution of unprotected phenols has long been considered as an attractive but challenging task. Herein, we describe a highly chemo‐ and ortho ‐selective substitution reaction of phenols with α‐aryl α‐diazoacetates with commercially available (C 6 F 5 ) 3 B as the catalyst. This reaction proceeds under simple and mild conditions with high efficiency, it features a wide substrate scope and can be easily scaled up.