Regioselective, Transition Metal-Free C–O Coupling Reactions Involving Aryne Intermediates

A new transition-metal-free synthetic method for C-O coupling between various aryl halides and alkoxides is described. This type of transformation is typically accomplished using palladium catalysts containing a specialized phosphine ligand. The reactions reported here can be performed under mild, ambient conditions using certain potassium alkoxides and a range of aryl halides, with iodide and bromide derivatives giving the best results. A likely mechanistic pathway involves the in situ generation of an aryne intermediate, and directing groups on the aryl ring inductively control regioselectivity.