抄録
(-)-Gelsemoxonine, a relatively new member of gelsemium alkaloids, was isolated from the leaves of Gelsemium elegans in 1991. While the structure of gelsemoxonine was misassigned originally, it was revised in 2003 by Aimi on the basis of an X-ray crystallographic analysis. The correct structure features the unique azetidine moiety bearing a tetra-substituted carbon center, which is quite unique among indole alkaloids. Combined with the quaternary center of the spiro-N-methoxy indolinone and the intricate cyclic system, gelsemoxonine posed a formidable challenge to synthetic chemistry. The first total synthesis of gelsemoxonine has been accomplished by means of 1) divinylcyclopropane-cycloheptadiene rearrangement of the highly functionalized substrate, which was successfully applied to assemble the spiro-quaternary carbon center connected to the bicyclic seven-membered core structure, as well as 2) a one-pot isomerization reaction from the α,β-unsaturated aldehyde to the saturated ester via the TMSCN-DBU combination that allowed a facile diastereoselective introduction of the latent nitrogen functionality of the unique azetidine moiety.
