Catalytic Enantioselective α-Allylation of Deconjugated Butenolides with Aza-π-allylpalladium 1,4-Dipoles: Access to Optically Pure 2-Piperidones Bearing an All-Carbon Quaternary Stereocenter

A palladium-catalyzed enantioselective α-allylation of deconjugated butenolides with aza-π-allylpalladium 1,4-diploes, in situ generated from palladium-mediated decarboxylation of cyclic carbamates and amide-substituted acyclic carbonates, has been successfully developed. An array of enantioenriched 2-piperidones bearing an all-carbon quaternary stereocenter were obtained in high yields with excellent enantioselectivities (up to 99% yield and 99% ee). The utility of this method was also showcased by a large-scale reaction and synthetic transformations of the product.