Nambu Hisanori
Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama.
Yakugaku Zasshi. 2018;138(1):19-25. doi: 10.1248/yakushi.17-00188.
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.
本综述描述了我们最近利用环己烷 -1,3 - 二酮 -2 - 螺环丙烷的开环环化反应开发高效合成杂环化合物（如吲哚和苯并呋喃）方法的工作，环己烷 -1,3 - 二酮 -2 - 螺环丙烷是通过1,3 - 环己二酮与锍盐反应制备的。环己烷 -1,3 - 二酮 -2 - 螺环丙烷与伯胺的开环环化反应在室温下进行，以良好至优异的产率提供2 - 取代的四氢吲哚 -4(5H)- 酮。所得产物可很容易地转化为2 - 取代的4 - 羟基吲哚衍生物。此外，环己烷 -1,3 - 二酮 -2 - 螺环丙烷的酸催化开环环化反应在室温下顺利进行，以优异的产率提供2 - 取代的四氢苯并呋喃 -4(2H)- 酮。所得产物可转化为2 - 取代的4 - 羟基苯并呋喃衍生物。通过对cuspidan B的全合成证明了该催化方法的合成实用性。
