Mild and efficient palladium-catalyzed intramolecular direct arylation reactions

The influence of ligand, stoichiometric base, and additive has been evaluated in the context of intramolecular direct arylation reactions. Under the optimal conditions, arylation of simple arenes can be performed under very mild conditions, with heating to 50 degrees C. The role of the pivalic acid additive is rationalized by invoking a concerted palladation-deprotonation pathway where the pivalate is behaving as either an intramolecular base from the palladium metal or through an intermolecular deprotonation in a similar manner as that previously described by Echavarren and Maseras. (C) 2008 Published by Elsevier Ltd.