Total Synthesis of the Alleged Structure of (+)-Fimbricalyxoid A

Abstract

An enantioselective total synthesis of the alleged structure of (+)-fimbricalyxoid A is reported. The synthetic strategy features a pyridine-N-oxidate-mediated S N 2′ reaction to introduce an oxygen functionality at position C3 of the A-ring and a sequential three-step process via the cleavage of the C−O bonds and hemiketalization to form the 3,20-oxybridge. With this strategy, the target molecule was synthesized in 19% overall yield and 12 steps from our previously synthesized cis-fused octahydrophenanthrene (+)-6.

Highly Efficient Asymmetric Hydrogenation Catalyzed by Iridium Complexes with Tridentate Chiral Spiro Aminophosphine Ligands

“…We used this highly efficient protocol for concise, divergent syntheses of the antiulcer drug rosaprostol and mulinane-type diterpenoids . We also achieved rapid and enantioselective construction of cis -fused octahydrophenanthrenes containing quaternary stereocenters, which allowed us to accomplish the first enantioselective total synthesis of the reported structure of (+)-fimbricalyxoid A …”

Strophiofimbrins A and B: Two Rearranged Norditerpenoids with Novel Tricyclic Carbon Skeletons from Strophioblachia fimbricalyx

“…belongs to Strophioblachia , a small genus of the Euphorbiaceae family, and mainly grows in Southeast Asia . It is commonly used by the ethnic Thai people to treat migraines and cancer. , Some phenanthrene-type (6/6/6 tricyclic) diterpenoids were discovered or synthesized in previous research on S. fimbricalyx , such as phenanthrenone and cleistanthane diterpenoids. − Interestingly, the type compounds were also isolated from some species of Trigonostemon , a closely related genus, which had some similar species to S. fimbricalyx in plant taxonomy . Otherwise, some 3,4- seco -cleistanthane diterpenoids were obtained from T. flavidus and T. chinensis . − …”