11 2-アルケニルチオアニリドのラジカル環化反応を用いた新規2,3-二置換インドール合成法とその応用(口頭発表の部)

概要

論文の詳細を見る
The indole nucleus is present in a wide range of natural products, and the synthesis of this important structure has been a steady topic of interest for many years. Herein we report a novel indole synthesis that is carried out under mild radical cyclization conditions. Tin-mediated radical cyclization of 2-alkenylthioanilides at room temperature using triethylborane as radical initiator takes place smoothly to furnish 2,3-disubstituted indoles in good to excellent yields. The indole formation reaction proved to be compatible with both acid and base sensitive substituents including esters, THP ethers, and a β-lactam. We also explored tin-free reaction conditions, and found that the indole formation reaction proceeds smoothly using excess AIBN and hypophosphorous acid in n-PrOH in the presence of triethylamine. In addition, modular synthesis of the necessary thioamide precursors was developed to give a wide range of functionality at the 2- and 3-positions on the indole skeleton, as well as at the 5- and 6-positions. 2-Indolylethanol derivatives, potentially useful building blocks for the construction of many indole-containing natural products, were easily synthesized by this method via a ring-opening reaction of quinolines. The methodology was by no means limited to these structures. Simple 2,3-dialkyl indoles were also synthesized easily by means of Sonogashira-coupling of 2-iodoaniline with terminal acetylenes and subsequent partial reduction by activated zinc. Finally, the reaction was applied to synthesis of an optically active β-carboline derivative and the indole alkaloid, catharanthine.
天然有機化合物討論会の論文
1999-09-01

11 2-アルケニルチオアニリドのラジカル環化反応を用いた新規2,3-二置換インドール合成法とその応用(口頭発表の部)

スポンサーリンク

概要

著者

関連論文

スポンサーリンク