Total Synthesis of (+)-Shahamin K

Keywords

(+)-shahamin K - spongiane diterpenoid - Johnson–Lemieux oxidation - Prins-pinacol cascade - Peterson olefination - Michael addition - Mukaiyama esterification

Significance

In 2001, Overman and co-workers reported the enantioselective total synthesis of ( + )-shahamin K, a spongiane diterpenoid natural product isolated from the dorid nudibranch Chromodoris gleniei. The central cis-hydroazulene motif was installed via a Prins–pinacol cascade. Spongiane diterpenoids have been investigated for their antimicrobial and fish antifeedant properties.

Comment

Thioacetal C was engaged in the pivotal Prins–pinacol cascade reaction by exposure to BF₃·Et₂O, affording ketone E in high yield. Subsequent Peterson olefination and oxidation furnished ketone G, which was then employed in a Michael addition to couple fragment H. Oxidation-state adjustment furnished keto alcohol J, which was subjected to a sequence consisting of Johnson–Lemieux oxidation, reduction, and Mukaiyama esterification to assemble the lactone moiety, affording ( + )-shahamin K.

Publication History

Article published online:
22 April 2025