A Stereospecific Transannular Diels-Alder Approach to the [6.6.7] Tricyclic Skeleton Related to Aphidicolin and Scopadulan Natural Products
作者:Dennis G. Hall、Alain-Sébastien Caillé、Marc Drouin、Serge Lamothe、Renate Müller、Pierre Deslongchamps
DOI:10.1055/s-1995-4077
日期:1995.9
Model trans-cis-cis (TCC) macrocyclic triene 7 was synthesized using a convergent approach. Upon heating at 200°C, a 1,5-hydrogen-shift on the diene moiety was found to compete with the transannular Diels-Alder (TADA) reaction, thus leading to a mixture of tricyclic products. However, the diene rearrangement could be avoided by using boron trifluoride-diethyl ether complex as catalyst at reduced temperature (60°C). The exclusive formation of the trans-syn-cis [6.6.7] (TSC) tricyclic product 8 through an endo approach was observed. This result demonstrates the feasibility of a TADA strategy for synthesizing the title compounds and analogs.
模型转-cis-cis (TCC) 大环三烯 7 是采用逐步合成的方法合成的。在200°C加热时,发现烯烃部分的1,5-氢转移与跨环Diels-Alder (TADA) 反应相竞争,从而导致三环产物的混合物。然而,通过在降低温度(60°C)下使用氟化硼-二乙醚络合物作为催化剂,可以避免烯烃重新排列。观察到通过内源性途径专一形成转-顺-顺 [6.6.7] (TSC) 三环产物 8。这一结果证明了TADA策略合成标题化合物及其类似物的可行性。