Juhl Martin, Nielsen Thomas E, Le Quement Sebastian, Tanner David
Department of Chemistry, Technical University of Denmark, Building 201, Kemitorvet, DK-2800 Kgs. Lyngby, Denmark.
J Org Chem. 2006 Jan 6;71(1):265-80. doi: 10.1021/jo0520691.
[reaction: see text] In connection with the total synthesis of the marine alkaloids zoanthamine and norzoanthamine, an elaborate model study was conducted starting from (-)-carvone. In nine steps alkenyl iodides corresponding to the C11-C24 fragment of zoanthamine were obtained. The alkenyl iodides were coupled to various stannanes (C6-C10 fragment) via the Corey modification of the Stille reaction, affording a variety of Diels-Alder precursors. An interesting and highly unexpected cascade reaction sequence was observed during the screening of an intramolecular Diels-Alder reaction, generating a novel tetracyclic framework. A slight modification in the Diels-Alder precursor allowed the desired cycloaddition to take place, giving the cycloadduct in 87% yield.
[反应：见正文] 关于海洋生物碱zoanthamine和去甲zoanthamine的全合成，从（-）-香芹酮开始进行了一项详尽的模型研究。经过九步反应，得到了与zoanthamine的C11-C24片段相对应的烯基碘化物。通过对Stille反应的Corey改进，将烯基碘化物与各种锡烷（C6-C10片段）偶联，得到了多种狄尔斯-阿尔德反应前体。在筛选分子内狄尔斯-阿尔德反应的过程中，观察到了一个有趣且非常意外的级联反应序列，生成了一个新的四环骨架。对狄尔斯-阿尔德反应前体进行轻微修饰，使所需的环加成反应得以发生，环加成产物的产率为87%。
