Cyclometallated compounds XIV. Kinetic versus thermodynamic control in the reversible cyclopalladation of 2-(2-naphthyloxy) pyridine

Reaction of 2-(2-naphthyloxy)pyridine with palladium acetate, in acetic acid at room temperature, gives, selectively, the kinetically controlled regioisomer from cyclopalladation in the 1-position, whereas, under reflux, the thermodynamically more stable 3-substituted isomer is exclusively formed. Furthermore, the 1-substituted isomer readily interconverts to the 3-substituted isomer on heating, indicating reversibility of the C-H bond-breaking step. That this is a general phenomenon is demonstrated by deuterium labelling experiments with related ligands. (C) 1999 Elsevier Science S.A. All rights reserved.