Synthesis and properties of (π-allyl)palladium formates as intermediates in palladium-catalyzed reductive cleavage of allylic acetates and carbonates with formic acid

Neutral (π-allyl)(tertiary phosphine)palladium formates and ionic (π-allyl)bis(tertiary phosphine)palladium formates that are regarded as key intermediates in palladium-catalyzed reductive cleavage of allylic acetates and carbonates with formic acid have been prepared and characterized by ¹H and ¹³C NMR spectroscopy. From a study of the formation process of these formate intermediates by anion exchange of the acetate anion with formic acid and by establishment of the course of liberation of olefins and CO₂ from the formate ligand, the validity of the proposed catalytic cycle has been substantiated.