Asymmetric Total Syntheses of Hetidine-Type C 20 -Diterpenoid Alkaloids: Spirasines V and VI, Spiradine D, and the Proposed Structures of Spirafines II and III - Fengjie Yao; Yufei Wu; Yidian Sheng; Kuan Yu; Peirong Rao; Jun Xuan; Hanfeng Ding (Journal of the American Chemical Society, 2025)