The synthetic chemistry of sarpagine–ajmaline-type alkaloids

The sarpagine-ajmaline type monoterpenoid indole alkaloids are among the most important groups of natural alkaloids, and the complex polycyclic and cage-like architectures present significant synthetic challenges. Because of their characteristic indole-fused azabicyclo[3.3.1]nonane structures and prominent biological activities, sarpagine-ajmaline related alkaloids have captured the attention of organic synthetic chemists for decades. In this chapter, the strategies employed in the synthesis of sarpagine-ajmaline related alkaloids are outlined, and the synthetic progress during the period of 2019-2023 is provided in detail. To provide potential targets for future synthetic endeavors, some sarpagine/ajmaline type alkaloids isolated in recent years with novel structures and biological activities are also summarized.