Application of the Helquist Annulation in <i>Lycopodium</i> Alkaloid Synthesis: Unified Total Syntheses of (−)-8-Deoxyserratinine, (+)-Fawcettimine, and (+)-Lycoflexine
作者:Yu-Rong Yang、Liang Shen、Jiu-Zhong Huang、Tao Xu、Kun Wei
DOI:10.1021/jo1023188
日期:2011.5.20
total synthesis of the Lycopodium alkaloids (−)-8-deoxyserratinine (7), (+)-fawcettimine (1), and (+)-lycoflexine (4) is detailed. The key features include a highly efficient Helquist annulation to assemble the cis-fused 6/5 bicycle, facile construction of the aza nine-membered ring system employing double N-alkylation strategy, providing access to the common tricyclic skeleton, asymmetric Shi epoxidation
为的全合成统一战略石松生物碱( - ) - 8-deoxyserratinine(7),(+) - fawcettimine(1),和(+) - lycoflexine(4)的详细说明。主要功能包括:高效的Helquist环空法,可组装顺式融合的6/5自行车;采用双N烷基化策略的氮杂九元环系统的简便构建,可提供通向常见的三环骨架的通道;不对称的Shi环氧化,可输送所需的β-环氧化物立体定向提供(-)-8-脱氧血黄素(7),SmI 2还原二羟基化衍生物35以形成(+)-法西替明(1),以及通过分子内曼尼希环化作用将(+)-法西替明(1)快速仿生转化为(+)-糖弹性蛋白(4)。