Tremorgenic Indole Alkaloids. 10. An Improved Asymmetric Synthesis of a Tricyclic Common Intermediate
作者:Amos B. Smith、Richard A. Hartz、P. Grant Spoors、Jon D. Rainier
DOI:10.1002/ijch.199700009
日期:——
An efficient third-generation asymmetric synthesis of tricyclic lactone (+)-1, designed to serve as the common intermediate for construction of the indole tremorgens, has been developed. The major challenge was stereocontrolled introduction of the vicinal quaternary methyl groups. Our initial approaches employed enolate chemistry to install the second methyl moiety; herein we exploit instead a hydroxyl-directed
已经开发出一种有效的第三代不对称合成三环内酯(+)-1,其设计用作构建吲哚震颤的常见中间体。主要的挑战是通过立体控制引入邻位季甲基。我们最初的方法是使用烯醇酸化学方法来安装第二个甲基部分。在本文中,我们改为利用羟基导向的席梦思-史密斯环丙烷化,然后还原性地打开三元环。新的15步合成法总产率为8.3%,比第二代途径提高了将近八倍,适合大规模生产(+)- 1。