Photoinduced Vitamin B12-Catalysis for Deprotection of (Allyloxy)arenes.

Vitamin B12 is a natural cobalt complex that, while reduced to the "supernucleophilic" Co(I) form, can easily react with electrophiles via an SN2 mechanism. It is also shown to react via an SN2' mechanism with allylic compounds allowing for photochemical deprotection of (allyloxy)arenes. A sustainable alternative to commonly used noble metal-catalyzed deprotection reactions is presented.