Tetracyclic diterpenoids make up a large number of terpenoid natural products extracted from plants and have drawn significant attention from the synthetic community due to their intricate carbocyclic framework. In the 2020 paper from Lou and co-workers, a divergent photochemical approach towards such diterpenoids namely ent-kauranes, ent-trachylobanes, ent-beyeranes, and ent-atisanes was disclosed. The impressive transformation is depicted below:
Give a detailed explanation on the photochemical transformation above.
For reference:
Xu, Z., Zong, Y., Qiao, Y., Zhang, J., Liu, X., Zhu, M., Xu, Y., Zheng, H., Fang, L., Wang, X., & Lou, H. (2020).
“Divergent Total Synthesis of Euphoranginol C, Euphoranginone D, ent‐Trachyloban‐3β‐ol, ent‐Trachyloban‐3‐one, Excoecarin E, and ent‐16α‐Hydroxy‐atisane‐3‐one.”
Angewandte Chemie International Edition, 59(45), 19919–19923.
DOI: 10.1002/anie.202009128