Benke Hong, Weilong Liu, Jin Wang, Jinbao Wu, Yuichiro Kadonaga, Pei-Jun Cai,Hong-Xiang Lou, Zhi-Xiang Yu, Houhua Li,,* and Xiaoguang Lei*
Chem 2019, 5(6), 1671-1681
Protecting-group-free synthesis of (+)-ent-kauradienone and
(-)-jungermannenone C has been accomplished through sequential applications
of three radical-based reactions, including late-stage photoinduced skeletal
rearrangements of bicyclo[3.2.1]octene ring systems. Further investigations on
various terpenoids showed good functional-group tolerance and suggest that
some terpenoids could also be produced via such photoinduced rearrangements
pathways in nature. Our work demonstrates how paying more attention to
unconventional radical mechanisms can reveal new chemistries that facilitate the
synthesis of complex natural products.
Protecting-group-free synthesis of (+)-ent-kauradienone and(-)-jungermannenone C has been accomplished through sequential applications of three radical-based reactions, including late-stage photoinduced skeletal rearrangements of bicyclo[3.2.1]octene ring systems. Further investigations on various terpenoids showed good functional-group tolerance and suggest that some terpenoids could also be produced via such photoinduced rearrangements pathways in nature. Our work demonstrates how paying more attention to unconventional radical mechanisms can reveal new chemistries that facilitate the synthesis of complex natural products.
Herein, we describe the protecting-group-free total synthesis of two structurally diverse Isodon diterpenoids, (+)-ent-kauradienone (3) and (−)-jungermannenone C (4), in 12 and 14 steps respectively, through sequential applications of three radical-based reactions, including the photoinduced skeletal rearrangements of bicyclo[3.2.1]octene ring systems. Further investigations of this photochemical radical rearrangement on a series of diverse terpenoids demonstrated both the unparalleled functional-group tolerance and the broad applicability of such late-stage photochemical rearrangements for the synthesis of structurally diverse and complex small molecules. Overall, the mild nature of late-stage photoinduced skeletal rearrangements might suggest that they are possible in a biological setting in unappreciated complimentary biosynthetic pathways.