A Fast Assembly of Pentacyclic Benz[<i>f</i>]indolo[2,3-<i>a</i>]quinolizidine Core by Tandem Intermolecular Formal Aza-[3 + 3] Cycloaddition/Pictet−Spengler Cyclization: A Formal Synthesis of (±)-Tangutorine
作者:Shengjun Luo、Jingrui Zhao、Hongbin Zhai
DOI:10.1021/jo049459s
日期:2004.6.1
pentacyclic benz[f]indolo[2,3-a]quinolizidine intermediate 3 (with an overall yield of 54% for three steps), featuring a tandem intermolecular formal aza-[3 + 3] cycloaddition/Pictet−Spengler cyclization. The present work can be considered as a formal synthesis of β-carboline alkaloid (±)-tangutorine. Our strategy disclosed herein constitutes a new effective generalsyntheticapproach toward the indoloquinolizidine
我们已经描述了五环苯并[ f ]吲哚并[2,3- a ]喹啉嗪中间体3(三个步骤的总产率为54%)的简洁结构,其特征在于串联分子间形式的氮杂-[3 + 3]环加成反应/ Pictet-Spengler环化。目前的工作可以被认为是β-咔啉生物碱(±)-tangutorine的正式合成。本文公开的我们的策略构成了对生物碱吲哚并喹喔啉家族的一种新的有效的通用合成方法。
Total synthesis of (±)-tangutorine and chiral HPLC separation of enantiomers
The first total synthesis of racemic tangutorine, a novel indole alkaloid, was performed in 7 steps. The key reactions, dithionite reduction and acidic cyclization provided easy access with good yields to the tangutorine skeleton. Comprehensive NMR spectroscopic data of new compounds are given. Chiral HPLC separation of enantiomers is reported.