In this study, we successfully developed a palladium-catalyzed decarboxylative (3 + 3) coupling cyclization reaction of vinyloxazolidine-2,4-diones with cyclopropenones, producing varieties of fully substituted unsaturated glutarimide derivatives. Additionally, scale-up experiments, asymmetric transformations, and derivations of products demonstrated the practical utility of this synthetic method. Preliminary mechanistic studies support that the cleavage of the C-C bond of cyclopropenone by Pd(0) species is the first step in the catalytic cycle.