Catalytic Allylic Substitution of Allyl Alcohols in Water

Abstract

Palladium-catalyzed allylic substitution with carbon nucleophiles is one of the most important reactions in transition metal-catalyzed synthetic methods. In most cases, allyl esters or allyl carbonates have been used as allylating agents. If allyl alcohols can be used as allylating agents, the overall process of the allylation would become highly efficient and atom economical. On the other hand, organic reactions in water have recently attracted much attention, not only because unique reactivity is often observed in water but also because water is a safe and economical substitute for conventional organic solvents. Here, we disclose a new catalytic system for palladium-catalyzed allylic substitution of allyl alcohols in water as a dispersion medium. The key is the use of a catalytic amount of a carboxylic acid such as 1-AdCO₂H, which dramatically accelerates the palladium-catalyzed allylic substitution.