Asymmetric Allylic Alkylation with Deconjugated Carbonyl Compounds: Direct Vinylogous Umpolung Strategy

An atom-economic and highly efficient vinylogous umpolung strategy is developed for deconjugated carbonyl compounds, which generate electron-deficient p-allylpalladium complexes with Pd(OAc)(2) under ligand-free conditions. In cooperation with a chiral-phosphonium-based phase-transfer catalyst, the asymmetric direct oxidative allylic alkylations of 3-substituted oxindoles are furnished under O-2 atmosphere. The gamma- or even remote epsilon-regioselective alkylation products, with substantial substituents, are delivered with excellent enantio-selectivity, and can be further used to access diverse chiral spirocyclic architectures effectively. The Mukaiyama dienol silyl ether can be utilized similarly, indicating that the current active pi-allylpalladium species results from tautomerization of the Pd-II-dienolate intermediate.