Exploiting multiple nucleophilic sites on pyrrole for the assembly of polyheterocyclic frameworks: application to a formal total synthesis of (±)-aspidospermidine
作者:Martin G. Banwell、Jason A. Smith
DOI:10.1039/b208821e
日期:——
The tricyclic ketone 19, an advanced intermediate in Aubé's recently reported synthesis of aspidospermidine (4), is prepared in twelve steps from pyrrole (3). The key transformations involve a previously described intramolecular Michael addition reaction of pyrrole 10 and intramolecular Friedel–Crafts type cyclisation of the derived carboxylic acid 15 to ketone 16. Careful hydrogenation of this last compound afforded the fully saturated alcohol 17 which was readily oxidised to the target ketone 19.
三环酮 19 是 Aubé 最近报道的蜘蛛精胺 (4) 合成过程中的高级中间体,由吡咯 (3) 经十二步制备而成。关键的转化涉及先前描述的吡咯 10 的分子内迈克尔加成反应以及衍生的羧酸 15 到酮 16 的分子内弗里德-克来福特型环化。最后一个化合物的仔细氢化提供了完全饱和的醇 17,它很容易被氧化成目标酮 19.