Gold- and copper-catalyzed [4+2] benzannulations between enynal or enynone units and 2π-systems

Naoki Asao

    Research output: Contribution to journalReview articlepeer-review

    173 Citations (Scopus)

    Abstract

    Gold-catalyzed formal [4+2] benzannulation between enynal or enynone units, including ortho-alkynyl(oxo)benzenes, and 2π-systems, such as alkynes and carbonyl compounds (enol forms), produces aromatic ketones in good to high yields. By simply changing the catalyst from gold to copper-Brønsted acid system, decarbonylated aromatic compounds can be prepared in the reactions using alkynes as the 2π-system. An efficient synthetic approach to angucyclinone antibiotics, (+)-ochromycinone and (+)-rubiginone B2, is developed by applying the present benzannulation to an intramolecular version. The reaction proceeds most probably through the formation of the benzo[c]pyrylium ate complex via the intramolecular nucleophilic addition of the carbonyl oxygen atom to the alkyne part of enynal or enynone units, which is induced by carbophilic gold and copper catalysts.

    Original languageEnglish
    Pages (from-to)1645-1656
    Number of pages12
    JournalSynlett
    Issue number11
    DOIs
    Publication statusPublished - 2006 Jul 12

    Keywords

    • (+)-ochromycinone
    • Benzo[c]pyrylium ate complexes
    • Carbophilic Lewis acids
    • Copper catalysis
    • Gold catalysis
    • [4+2] benzannulation

    ASJC Scopus subject areas

    • Organic Chemistry

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