SmI<sub>2</sub>-Mediated Radical Coupling Strategy to Securinega Alkaloids: Total Synthesis of (−)-14,15-Dihydrosecurinine and Formal Total Synthesis of (−)-Securinine
The asymmetric totalsynthesis of (−)-14,15-dihydrosecurinine and the formal totalsynthesis of (−)-securinine were accomplished starting from an easily available malimide. A concise SmI2-mediated radical couplingstrategy has been developed to construct the bridged α-hydroxy 6-azabicyclo[3.2.1]octanone in four steps with high diastereoselectivity.
surprising rearrangement was observed during the reaction of securinine with tribromo-isocyanuric acid or 1,3-dibromo-5,5-dimethylhydantoin in methanol, yielding a stereoselective ringcontraction norsecurinine derivative. Meanwhile two oxidation rearrangement products were also reported. Some preliminary discussions on the reactivity of securinine were conducted from these rearrangements; it is believed