Palladium-Catalyzed ortho -C-H Alkoxycarbonylation of Aromatic Aldehydes via a Transient Directing Group Strategy.

Transient directing groups (TDGs) can be a powerful strategy for directly functionalizing C-H bonds of aldehydes. We report a palladium-catalyzed o -C-H alkoxycarbonylation of benzaldehydes using a catalytic amount of aromatic amine to form a transient imine that plays the role of a monodentate TDG. The reaction conditions were applied to a broad range of aldehydes, and the corresponding 2-formyl benzoates were used as direct precursors for the synthesis of phthalides and 1-isoindolinones.