Progress in the Total Synthesis of the Kopsia Alkaloids Arboridinine and Arborisidine

Indole alkaloids are widely distributed in nature and have rich pharmacological activities, so many indole alkaloids have emerged as hot targets for the total synthesis of natural products.The alkaloids arboridinine and arborisidine were isolated from a plant of the Kopsia genus found in Malaysia by Kam and co-workers in 2015 and 2016, respectively.These two pentacyclic monoterpenoid indole alkaloids have unique caged skeleton with multiple chiral centers.The highly complex cage structure of these alkaloids has brought great challenges to their total synthesis research.In addition, arborisidine combined with pimelautide exhibits clear anti-gastric cancer activity.The complex and attractive chemical structure and potential pharmacological activity, together with an extremely low natural abundance make their total synthesis extremely attractive.Soon after the isolation, their total synthesis has received extensive and sustained attention.Up to now, the total synthesis of arboridinine has be achieved by the Snyder, Ma, Zhai and Li groups, and the total synthesis of arborisidine by the Snyder, Ma, Zhu, Jiao, She and Gao groups.This review summarizes the research progress of total synthesis of arboridinine and arborisidine, in order to provide reference for the total synthesis of the related natural products.