Lewis acid-catalyzed [4 + 2] benzannulation between enynal units and enols or enol ethers: Novel synthetic tools for polysubstituted aromatic compounds including indole and benzofuran derivatives

Naoki Asao, Haruo Aikawa

    Research output: Contribution to journalArticlepeer-review

    124 Citations (Scopus)

    Abstract

    The reaction of enynals 1, including o-(alkynyl)benzaldehydes, and carbonyl compounds 2, such as aldehydes and ketones, in the presence of a catalytic amount of AuBr3 in 1,4-dioxane at 100 °C gave the functionalized aromatic compounds 3 in high yields. Similarly, the AuBr3-catalyzed reactions of 1 with acetal compounds 5 afforded the corresponding aromatic compounds 3 in good yields. On the other hand, when the reaction was carried out in the presence of a catalytic amount of Cu(NTf2)2 and 1 equiv of H2O in (CH2Cl)2 at 100 °C, the decarbonylated naphthalene products 4 were obtained selectively over 3. Benzofused heteroaromatic compounds, such as indole derivatives 13 and benzofuran derivatives 15, were also synthesized by using the present benzannulation methodology.

    Original languageEnglish
    Pages (from-to)5249-5253
    Number of pages5
    JournalJournal of Organic Chemistry
    Volume71
    Issue number14
    DOIs
    Publication statusPublished - 2006 Jul 7

    ASJC Scopus subject areas

    • Organic Chemistry

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