Cobalt-Catalyzed C-H Acetoxylation of Phenols with Removable Monodentate Directing Groups: Access to Pyrocatechol Derivatives.

An efficient cobalt-catalyzed C-H acetoxylation of phenols has been developed by using PIDA (phenyliodine diacetate) as a sole acetoxy source to synthesize pyrocatechol derivatives for the first time. The key feature of this method is the use of earth-abundant metal cobalt as the green and inexpensive catalyst for the acetoxylation of C(sp2)-H bonds under neutral reaction conditions. Furthermore, the gram-scale reaction and late-stage functionalization demonstrated the usefulness of this method.