Bioinspired Total Synthesis of Oxidized Securinega Alkaloids: Chemical Insights for the Elucidation of Biogenetic Pathway

Abstract

For over 60 years, more than 60 Securinega alkaloid natural products have been isolated from plants of Phyllanthaceae family. Their diverse structure and biological activity have drawn attention from the synthetic community.1 In 2018, novel type of oxidized Securinega alkaloid fluvirosaones A and B were isolated from Flueggea virosa. They represent the first pentacyclic Securinega alkaloids with three additional carbons unit on the piperidine or pyrrolidine ring.2 Herein, we present our biogenetically inspired endeavor to ent-fluvirosaones A and B. Discovery of regioselective oxidation of allosecurinine provided the key intermediate for the exploration of the synthetic route to natural products. Skeletal rearrangement of indolizidine core was realized for the first time with Securinega alkaloid compound providing new insight for the biogenetic pathways of these natural products. . . 1 Wehlauch, R.; Grendelmeier, S. M.; Miyatake-O. H.; Sandtorv, A. H.; Scherer, M.; Gademann, K., Org. Lett. 2017, 19, 548−551. 2 Luo, X.-K.; Cai, J.; Yin, Z.-Y.; Luo, Pan.; Li, C.-J.; Ma, H.; Seeram, N. P.; Gu, Q.; Xu, J. Org. Lett. 2018, 20, 991–994.