Synthesis of Prenyl- and Geranyl-Substituted Carbazole Alkaloids by DIBAL-H Promoted Reductive Pyran Ring Opening of Dialkylpyrano[3,2-<i>a</i>]carbazoles
作者:Ronny Hesse、Olga Kataeva、Arndt W. Schmidt、Hans-Joachim Knölker
DOI:10.1002/chem.201403645
日期:2014.7.28
The DIBAL‐H promotedreductivepyranringopening of dialkylpyrano[3,2‐a]carbazoles provides a direct access to a broad range of prenyl‐ and geranyl‐substituted carbazoles. Formation of a pyranring followed by reductiveringopening represents a new method for the introduction of prenyl and geranyl groups. In the course of the present work, we achieved the first total syntheses of the following eight
DIBAL-H促进了二烷基吡喃并[3,2- a ]咔唑的还原吡喃环的打开,可直接使用各种异戊二烯基和香叶基取代的咔唑。吡喃环的形成然后还原性开环代表了引入异戊二烯基和香叶基的新方法。在目前的工作过程中,我们完成了以下八种咔唑生物碱的首次合成:clauraila-E,7-羟基庚茶碱,7-甲氧基庚茶碱,mukoenine-B(clausenatine-A),mukoenine-A(girinimbilol),mahanimbinol (马哈宁比洛),欧司他汀-A和异莫拉利福林-B.
Total synthesis and neuroprotective effect of O-methylmurrayamine A and 7-methoxymurrayacine
O-Methylmurrayamine A (7) and 7-methoxymurrayacine (8) are natural products isolated from Murraya koenigii and Murraya siamensis, respectively. In this paper, we report the synthesis of 7 and 8 which are featured in the key step of cyclization to form carbazole intermediate 5 with mild conditions. The structures were confirmed by H-1 NMR, C-13 NMR, and HR-ESI-MS. In addition, compounds 7 and 8 were tested for their neuroprotective effects against H2O2 -induced PC12 cell damage. The results showed that compounds 7 and 8 have neuroprotective effect.