Asymmetric Total Synthesis of Sarpagine-Related Indole Alkaloids Hydroxygardnerine, Hydroxygardnutine, Gardnerine, (E)-16-epi-Normacusine B, and Koumine
文摘
Sarpagine-related indole alkaloids (−)-hydroxygardnerine, (+)-hydroxygardnutine, (−)-gardnerine, (+)-(E)-16-epi-normacusine B, and (−)-koumine were divergently synthesized via a common intermediate possessing a piperidine ring with an exocyclic (E)-ethylidene side chain, which was constructed by a gold(I)-catalyzed 6-exo-dig cyclization strategy.