Palladium-Catalyzed Ligand-Enabled Cyclization of Substituted Aliphatic Carboxylic Acids with Allylic Electrophiles.

A palladium-catalyzed cyclization of the β-C(sp)-H bond of aliphatic carboxylic acids with allylic electrophiles providing five-membered γ-lactones in good to excellent yields is demonstrated. An acetyl-protected aminoethyl phenyl thioether ligand is used to promote the C-H activation reaction. A diverse range of allylic electrophiles such as allyl alcohols, allyl acetates, allyl sulfones, allyl phosphonate, allyl amine, and allyl ester have been utilized for this reaction. A feasible reaction mechanism has been proposed to account for the present cyclization reaction.