Palladium-Catalyzed Reductive Coupling of Acid Chlorides with β-Stannyl Enones: Synthesis of 1,4-Diketones and Mechanistic Aspects

Article abstract of DOI:10.1021/jo00094a032

The palladium-catalyzed coupling of acid chlorides with (E)-1,2-bis(tri-n-butylstannyl)ethene or β-stannyl enones gives butane-1,4-diones directly by reduction of the intermediate enedicarbonyl intermediate.The double bond conjugated with a single carbonyl group was not significantly reduced.The generality of the method is illustrated by two syntheses of the 1,4-diketone ipomeanine.By performing the reaction at lower temperatures, α,β-unsaturated 1,4-diketones can also be prepared.The reduction of the intermediate α,β-unsaturated 1,4-diketones probably proceeds by insertion of a palladium hydride, formed in situ by reaction of a Pd(II) complex with Bu3SnCl, followed by hydrolysis of the intermediate palladium enolate.