作者:Yuji Mori、Keisuke Yaegashi、Hiroshi Furukawa
DOI:10.1021/jo980320p
日期:1998.9.1
The synthesis of the tetracyclic structure of hemibrevetoxin B (1) was achieved through a linear approach involving sequential coupling of three kinds of sulfonyl-stabilized oxiranyl anions, 5b, 6b, and 7b, to the monocyclic tetrahydropyran 4 containing the requisite substituents. Two iterations of alkylation of an oxiranyl anion and 6-endo cyclization provided the 6,6,6-tricyclic ring system 34, which
半短毒素B(1)的四环结构的合成是通过线性方法实现的,该方法涉及将3种磺酰基稳定的环氧乙烷基阴离子5b,6b和7b顺序偶联到含有必需取代基的单环四氢吡喃4上。氧代氧烷基阴离子的烷基化和6-内-环化的两次迭代提供了6,6,6-三环系统34,其通过使用三甲基甲硅烷基重氮甲烷的扩环而有效地转化为6,6,7-环系统35。使用环氧乙烷基阴离子方法和刚刚描述的扩环的组合将最终的环氧丙烷环安装到38中。立体选择性地将叔甲基引入41,得到四环化合物42a,其包含所有不对称中心1。