A short total synthesis of the indolopyridine alkaloids angustine (1) and angustoline (2) has been achieved in five and six steps, respectively. Two key steps for assembly of the pentacyclic core included a Bischler-Napieralski cyclization and a cobalt-catalyzed carbonylative lactamization. A late-stage Mukaiyama hydration allowed the first successful transformation of angustine (1) to angustoline (2). (C) 2020 Published by Elsevier Ltd.
Nine newindolealkaloids, vinmajines A–I (1–9), and 43 known indolealkaloids were isolated from cultivated Vincamajor in Kunming. The new structures were elucidated by extensive spectroscopic and quantum theory analysis. In addition, the results also supported that types of indolealkaloids from V. major might be influenced significantly by the ecological environment.