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Facile Preparation of 2Z,4E-Dienamides by the Olefination of Electron-deficient Alkenes with Allyl Acetate
Published on: June 21, 2017
Rh-Catalyzed Chemodivergent Parallel Kinetic Resolution and Desymmetrization of Enynes and Dienynes with Acrylamides
Shintaro Hamada1, Julong Jiang2, Yu Sato1
1Department of Chemical Science and Engineering, Institute of Science Tokyo, Meguro-ku, Tokyo, Japan.
Abstract:
Catalytic enantioselective synthesis of structurally diverse 3D molecules remains a central challenge in organic chemistry. Intermolecular chemodivergent parallel kinetic resolution (PKR) of racemic substrates through C─C bond formation using a single catalyst to yield distinct products is rare. Here, we report Rh-catalyzed chemodivergent PKR of racemic 1,6-enynes with α-fluoroacrylamides or mixtures of different acrylamides, proceeding via [2+2+2] cycloaddition and C-H alkylation to afford structurally and stereochemically distinct products with high selectivity under mild conditions. Additionally, substituent-dependent enantioselective desymmetrization of symmetric dienynes was achieved. Computational studies revealed that, depending on the stereochemistry of the 1,6-enyne, steric repulsion between the ligand and the enyne favors a compact C-H activation transition state, whereas its absence favors a C═C insertion transition state involving a smaller bond dissociation energy. These findings establish a versatile catalytic platform for the selective generation of 3D molecular complexity, advancing diversity-oriented synthesis from racemic or symmetric precursors.
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