A Carbometallation-Intramolecular Cycloaddition Strategy for the AB-Taxane Ring and an Enone Accelerated Cope Rearrangement to Bicyclo[2.2.2]octanones
作者:Pat Forgione、Peter D. Wilson、Glenn P. A. Yap、Alex G. Fallis
DOI:10.1055/s-2000-6291
日期:——
The one pot transformation of the magnesium chelates, derived from alkynyl alcohols, into tetraene-diols for the construction of substituted bicyclo[5.3.1]undecenes is described. This sequence affords a direct route to the AB-taxane ring system via a Lewis acid catalyzed intramolecular Diels-Alder reaction. The cycloaddition gives a single diastereomer due to the preferential formation of the Et2AlCl chelate. This adduct undergoes a facile enone accelerated Cope rearrangement to generate a substituted bicyclo[2.2.2]octanone. This isomerization fails below 110 °C when the ketone is absent.
本研究描述了从炔醇中提取的镁螯合物向四烯二醇的一锅转化过程,以构建取代的双环[5.3.1]十一烯。该序列通过路易斯酸催化的分子内 Diels-Alder 反应提供了通向 AB-三烷环系统的直接途径。由于 Et2AlCl 螯合物的优先形成,该环化反应产生了单一非对映异构体。这种加合物经过简单的烯酮加速科普重排,生成取代的双环[2.2.2]辛酮。当酮不存在时,这种异构化反应在温度低于 110 °C 时会失败。
Part 1: Efficient strategies for the construction of variably substituted bicyclo[5.3.1]undecenones (AB taxane ring systems)
作者:Alain Laurent、Nidia P Villalva-Servín、Pat Forgione、Peter D Wilson、David V Smil、Alex G Fallis
DOI:10.1139/v03-200
日期:2004.2.1
containing variably substituted bicyclo[5.3.1]undecenones (AB taxane ringsystems) are described. These routes employ a multi-component coupling protocol that utilizes sequential magnesium-mediated carbometallation of propargyl alcohols and intramolecular DielsAlder reactions (IMDA). The cycloaddition generates the key eight-membered taxane ring as a single diastereomer, induced by preferential Lewis acid