Cyclometalated Compounds. XVI. Double Cyclopalladations of Bis(2-pyridyloxy)naphthalenes. Kinetic versus Thermodynamic Control of Regiospecificity

A systematic study of the cyclopalladation reactions of bis(2-pyridyloxy)naphthalenes is described. On the basis of a kinetic preference for reaction at the 1-position, over thermodynamically favored reaction in the 3-position, a diverse range of doubly cyclopalladated compounds has been prepared, in a predictable manner, simply by moderating the experimental reaction conditions. Seven isomeric ligands have been employed to prepare many doubly metallated derivatives, all of which have been fully characterized by NMR spectroscopy, and two of which have been the subject of X-ray structure determinations. This study significantly expands the library of doubly cyclopalladated compounds, particularly those involving six-membered metallocycles.