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Brønsted Acid Catalyzed Cyclization of Hydroxylated Enynes: A Concise Synthesis of Five-Membered Heterocycles

Authors

  • Dr. Ke-Gong Ji,

    1. State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China), Fax: (+86) 931-891-2582
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  • Jin Chen,

    1. State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China), Fax: (+86) 931-891-2582
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  • Hai-Tao Zhu,

    1. State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China), Fax: (+86) 931-891-2582
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  • Fang Yang,

    1. State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China), Fax: (+86) 931-891-2582
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  • Ali Shaukat,

    1. State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China), Fax: (+86) 931-891-2582
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  • Prof. Dr. Yong-Min Liang

    Corresponding author
    1. State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China), Fax: (+86) 931-891-2582
    2. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000 (P.R. China)
    • State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000 (China), Fax: (+86) 931-891-2582
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Abstract

A mild and direct pathway for the formation of five-membered heterocyclic compounds from hydroxylated enynes has been developed. In this reaction, hydroxylated enynes were selectively transformed into five-membered heterocyclic compounds 2, with an allene moiety at the 3-position, in the presence of F3CSO3H (0.1 mol %). When R1, R2=Ph, diphenylvinyl-2,3-dihydro-1H-pyrrole (2 y) was obtained. With HSbF6 (5 mol %) as the catalyst, polycyclic skeletons 3 and 4 with adjacent stereocenters were obtained. When R1=H and R2=styrene, 1,3-dienyl-2,5-dihydro-1H-pyrrole (6 as) was formed. This Brønsted acid catalyzed domino process involves the formation of an allene carbocation intermediate, which can be readily trapped by olefins to give various novel five-membered heterocyclic skeletons.

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