Studies on the Novel Diterpenoids of the Formosan Soft Coral Cespitularia sp.
Abstract (Summary)Five new compounds were isolated from the soft coral Cespitularia sp.collected in Green Island, Taiwan. They are G8-7-7-A (1), G8-9-15-30-A(2), G8-10-B (3), G8-7-6-A (4) and G8-7-5-A (5). All of them belong to diterpenes with three methyl groups at C-16, C-17 and C-18, and an exocyclic double bond between C-4 and C-18. Compounds 1 and 2 are bicycle norditerpenes. G8-7-7-A (1) possesses a 6/13 ring and has an endocyclic double bond between C-7 and C-8. It also contains a hydroxyl group at C-6, a ketone group at C-12 and a lactone ring between C-10 and C-11. G8-9-15-30-A (2) is different from 1 at the lactone ring position. The lactone ring of 2 is between C-10 and C-12, and the ketone group is at C-11. So compound 2 possesses a 6/14 bicyclic ring system. Compounds 3-5 are cespitularin diterpenes, which belong to a 5/6/12 tricyclic ring. They all have an endocyclic double bond between C-7 and C-8. G8-10-B (3) contains an £\-hydroxy-£],£^-epoxy-£_-acetoxy furan and a hydroxyl group at C-6. The only difference between compounds 3 and 4 are substiuents at C-20. The C-20 position of 4 is an acrylic group, while compound 3 has an acetoxyl group at C-20. G8-7-5-A (5) contains an £^-hydroxy-£\,£]-unsaturated-£^-lactone function and a ketone group at C-6. Their structures were elucidated by mass, IR, 1D and 2D NMR spectroscopic analysis.
Advisor:Ya-ching Shen; none; none
School Location:China - Taiwan
Source Type:Master's Thesis
Date of Publication:07/26/2006