Palladium-Catalyzed Carbonylation of Vinyl Halides: A Route to the Synthesis of α-Methylene Lactones

Article abstract of DOI:10.1021/jo00140a007

α-Methylene γ-lactones were synthesized in high yields by the palladium-catalyzed carbonylation reactions of alkyl-substituted 3-bromobut-3-en-1-ols under mild conditions.The bromo alcohols were obtained by the reaction of <1-(trimethylsilyl)vinyl>magnesium bromide with various epoxides followed by conversion of the trimethylsilyl group to bromide.By starting with optically active epoxides such as (R)-1,2-epoxypropane or (2R,3R)-2,3-epoxybutane, the corresponding lactones could be obtained virtually optically pure.The carbonylation reaction is selective in that it generates only γ-lactones when there is a choice of two vinylic iodides or two alcohols that could lead either to the five- or six-membered rings.