Organotin Nucleophiles. 5. Palladium-Catalyzed Allylic Propargylation with Allenylstannane

Article abstract of DOI:10.1021/jo00174a027

Allenyltrialkylstannanes were found to react with various allylic acetates in the presence of catalytic amounts of Pd(PPh3)4 under mild neutral conditions, providing a novel approach for obtaining the 1,5-enyne carbon skeleton.The regioselectivity of propargylation depends largely on the electron-withdrawing properties of the substituents at the two ends of the allylic system: substitution occurs at the end of closer proximity to the more electronegative group.Allylic cyanohydrin acetates are substituted at a position α to the cyano group along with formation of a reduced side product.Several mechanistic aspects of these reactions are discussed.