Abstract
This review describes our recent efforts to develop efficient methods for the synthesis of heterocyclic compounds, such as indoles and benzofurans, employing ring-opening cyclization of cyclohexane-1,3-dione-2-spirocyclopropanes, which were prepared by the reaction of 1,3-cyclohexanediones with sulfonium salts. Ring-opening cyclization of cyclohexane-1,3-dione-2-spirocyclopropanes with primary amines proceeded at room temperature to provide 2-substituted tetrahydroindol-4(5H)-ones in good to excellent yield. The obtained product was readily converted into a 2-substituted 4-hydroxyindole derivative. Furthermore, acid-catalyzed ring-opening cyclization of cyclohexane-1,3-dione-2-spirocyclopropanes proceeded smoothly at room temperature to provide 2-substituted tetrahydrobenzofuran-4(2H)-ones in excellent yield. The obtained product was converted into a 2-substituted 4-hydroxybenzofuran derivative. The synthetic utility of this catalytic protocol was demonstrated by the total synthesis of cuspidan B.
Original language | English |
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Pages (from-to) | 19-25 |
Number of pages | 7 |
Journal | Yakugaku Zasshi |
Volume | 138 |
Issue number | 1 |
DOIs | |
State | Published - 2018 |
Keywords
- Benzofuran
- Cyclization
- Indole
- Ring-opening
- Spirocyclopropane
- Sulfonium salt
ASJC Scopus subject areas
- Pharmacology
- Pharmaceutical Science