Catalytic Asymmetric\nTransfer Hydrogenation of β,γ-Unsaturated\nα‑Diketones

Asymmetric transfer hydrogenation (ATH) has been recognized\nas\na highly valuable strategy that allows access to enantioenriched substances\nand has been widely applied in the industrial production of drug molecules.\nHowever, despite the great success in ATH of ketones, highly efficient,\nregio- and stereoselective ATH on enones remains underdeveloped. Moreover,\noptically pure acyloins and 1,2-diols are both extremely useful building\nblocks in organic synthesis, medicinal chemistry, and materials science,\nbut concise asymmetric approaches allowing access to different types\nof acyloins and 1,2-diols have scarcely been discovered. We report\nin this paper the first highly efficient ATH of readily accessible\nβ,γ-unsaturated α-diketones. The protocol affords\nfour types of enantioenriched acyloins and four types of optically\npure 1,2-diols in highly regio- and stereoselective fashion. The synthetic\nvalue of this work has been showcased by the divergent synthesis of\nfour related natural products. Moreover, systematic mechanistic studies\nand density functional theory (DFT) calculations have illustrated\nthe origin of the reactivity divergence, revealed the different roles\nof aromatic and aliphatic substituents in the substrates, and provided\na range of unique mechanistic rationales that have not been disclosed\nin ATH-related studies.