A Carbometallation-Intramolecular Cycloaddition Strategy for the AB-Taxane Ring and an Enone Accelerated Cope Rearrangement to Bicyclo[2.2.2]octanones
A Carbometallation-Intramolecular Cycloaddition Strategy for the AB-Taxane Ring and an Enone Accelerated Cope Rearrangement to Bicyclo[2.2.2]octanones
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DOI：
10.1055/s-2000-6291
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发表时间：
2000
期刊：
影响因子：
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通讯作者：
P. Forgione;P. D. Wilson;G. Yap;A. G. Fallis
中科院分区：
文献类型：
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作者：
P. Forgione;P. D. Wilson;G. Yap;A. G. Fallis
：描述了由炔醇衍生的镁螯合物一锅转化为四烯二醇，以构造取代的双环[5.3.1]十一烯。该序列通过Lewis酸催化的Diels - Alder分子内反应为ab -紫杉烷环体系提供了一条直接途径。由于Et 2 AlCl螯合物优先形成，环加成得到单一的非对映体。该加合物经过烯酮加速的Cope重排生成取代的双环-lo[2.2.2]辛酮。当酮不存在时，在110℃以下异构化失败。
: 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 Et 2 AlCl chelate. This adduct undergoes a facile enone accelerated Cope rearrangement to generate a substituted bicyc-lo[2.2.2]octanone. This isomerization fails below 110 °C when the ketone is absent.