Total Syntheses of (+)‐Villocarine A, (−)‐Apogeissoschizine, and (+)‐Geissoschizine
Jukiya Sakamoto, Mariko Kitajima, Hayato Ishikawa
Abstract
Total syntheses of geissoschizine-type monoterpenoid indole alkaloids (MTIAs) are reported. An intramolecular Pictet-Spengler cyclization was developed for the selective construction of the 3R stereocenter. The first total synthesis of (+)-villocarine A was then achieved. Furthermore, the first total synthesis of the highly strained (-)-apogeissoschizine was also accomplished in an aza-Michael cyclization/E1cB elimination/stereoselective olefin isomerization sequence. Finally, (+)-geissoschizine, a common biosynthetic intermediate of MTIAs, was obtained from apogeissoschizine through ring-opening along with a release of ring strain.
Topics & Concepts
StereocenterTotal synthesisIntramolecular forceStereoselectivityRing (chemistry)StereochemistryChemistryIndole testOlefin fiberIsomerizationRing strainSequence (biology)Organic chemistryEnantioselective synthesisCatalysisBiochemistryAlkaloids: synthesis and pharmacologyTraditional and Medicinal Uses of AnnonaceaeChemical synthesis and alkaloids