• Title/Summary/Keyword: Tandem cyclization

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Synthesis of 3,4,5-Trisubstituted Isoxazoles through Gold-Catalyzed Cascade Cyclization-Oxidative Alkynylation and Cyclization-Fluorination of 2-Alkynone O-Methyloximes

  • Song, Doo-Hee;Ryu, Jae-Sang
    • Bulletin of the Korean Chemical Society
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    • v.35 no.9
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    • pp.2635-2644
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    • 2014
  • Gold-catalyzed tandem cyclization-oxidative alkynylation and cyclization-fluorination reactions of 2-alkynone O-methyloximes are described. The reactions proceed smoothly at room temperature in the presence of 10 mol % of $(PPh_3)AuNTf_2$, 2.5 equivalents of selectfluor, and 2 equivalents of $K_3PO_4$. 2-Alkynone O-methyloximes undergo intramolecular oxyauration/cyclization and ensuing oxidative cross-coupling and fluorination process to afford the corresponding 3,4,5-trisubstituted isoxazoles in a cascade manner.

A Facile and Efficient Synthesis of Dronedarone Hydrochloride

  • Li, Feng;Jin, Chunhua;Zou, Jianwei;Wu, Jun
    • Bulletin of the Korean Chemical Society
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    • v.35 no.7
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    • pp.1970-1972
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    • 2014
  • A facile and efficient synthesis of dronedarone hydrochloride starting from commercially available 4-nitrophenol is described. This approach features a tandem-type synthesis of 3-carbonylated benzofuran involving cyclization of 2-ethynylphenol followed by $CO_2$ fixation at the 3-position of the benzofuran ring mediated by potassium carbonate without the addition of any transition metal catalyst.

Synthesis of Cyclohexene Derivatives from 1,5-Enynes via Gold-Catalysis and Iodocyclization: A Comparative Study and Applications in the Synthesis of 7/5- or 8/5-Fused Rings and Biaryls

  • Lee, Young-Un;Lim, Choong-Min;Kim, Sung-Hwan;Shin, Seung-Hoon
    • Bulletin of the Korean Chemical Society
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    • v.31 no.3
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    • pp.670-677
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    • 2010
  • A comparative study on the Au(I)-catalyzed and IBr-promoted tandem cyclization of 1,5-enyne was reported. This study provides a meaningful mechanistic insight to the concerted nature of this tandem reaction and also provides interesting applications in the synthesis of 7/5- or 8/5-fused bicycles and biaryls.

Facile Formation of Unexpected [m,6,n]-tricyclic Spiranes via Intramolecular [3+2] Cyclization of Platinum-bound Pyrylium with Alkenes

  • Oh, Chang-Ho;Tak, Sang-Yong;Lee, Ji-Ho;Piao, Lanhua
    • Bulletin of the Korean Chemical Society
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    • v.32 no.spc8
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    • pp.2978-2980
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    • 2011
  • Enynals bearing an olefinic pendant were successfully cyclized via Huisgen-type [3+2] cycloaddition to the tetracyclic Pt-carbene complexes which would undergo insertion into a C-H bond of the ${\beta}$-position to afford the fused cyclopropane intermediates. Their tandem rearrangement afforded diverse types of spiranes depending on the tethered alkenes of the enynals.

An Efficient Synthesis of Substituted Quinolines via Indium(III) Chloride Catalyzed Reaction of Imines with Alkynes

  • Zhu, Mei;Fu, Weijun;Xun, Chen;Zou, Guanglong
    • Bulletin of the Korean Chemical Society
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    • v.33 no.1
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    • pp.43-47
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    • 2012
  • An efficient synthetic method for the preparation of quinolines through indium(III) chloride-catalyzed tandem addition-cyclization-oxidation reactions of imines with alkynes was developed. The processes can provide a diverse range of quinoline derivatives in good yields from simple imines and alkynes.