10.1021/jo1023188.s002 Yu-Rong Yang Yu-Rong Yang Liang Shen Liang Shen Jiu-Zhong Huang Jiu-Zhong Huang Tao Xu Tao Xu Kun Wei Kun Wei Application of the Helquist Annulation in <i>Lycopodium</i> Alkaloid Synthesis: Unified Total Syntheses of (−)-8-Deoxyserratinine, (+)-Fawcettimine, and (+)-Lycoflexine American Chemical Society 2011 intramolecular Mannich cyclization strategy Lycopodium Alkaloid Synthesis biomimetic transformation tricyclic skeleton Shi epoxidation Helquist Annulation deoxyserratinine Helquist annulation fawcettimine lycoflexine 2011-05-20 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Application_of_the_Helquist_Annulation_in_i_Lycopodium_i_Alkaloid_Synthesis_Unified_Total_Syntheses_of_8_Deoxyserratinine_Fawcettimine_and_Lycoflexine/2649877 A unified strategy for total synthesis of the <i>Lycopodium</i> alkaloids (−)-8-deoxyserratinine (<b>7</b>), (+)-fawcettimine (<b>1</b>), and (+)-lycoflexine (<b>4</b>) 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, delivering the desired β-epoxide stereospecifically to furnish (−)-8-deoxyserratinine (<b>7</b>), SmI<sub>2</sub> reduction of dihydroxylation derivative <b>35</b> to enable formation of (+)-fawcettimine (<b>1</b>), and a rapid biomimetic transformation of (+)-fawcettimine (<b>1</b>) into (+)-lycoflexine (<b>4</b>) via an intramolecular Mannich cyclization.