Catalytic intermolecular ortho-arylation of phenols

The use of rhodium catalysts such as [RhCl(PPh3)(3)] or [{RhCl(COD)}(2)] with PiPr(2)(OAr) or P(NMe2)(3) co-catalysts allows the ortho-selective intermolecular arylation of phenols. The reaction proceeds via orthometalation of P-OAr groups and then transesterification liberates the product phenol. When 2-substituted phenols are used as substrates, [RhCl(PPh3)(3)]/iPr(2)(OAr) mixtures are typically the catalysts of choice, whereas for substrates without 2-substitution [{RhCl(COD)}(2)]/P(NMe2)(3) mixtures tend to give better results.