Telesto riisei

Punaglandin 4 (PUG 4, 151, Figure 6.10) is one of the chlorinated marine prostanoids isolated from a Hawaiian octocoral, Telesto riisei, by Scheuer and coworkers in 1985. Its remarkable antitumor activity coupled with its unique structure attracted the attention of chemists, and its synthesis was achieved by Yamada, Noyori, Shibasaki, and Mori s groups. Our synthesis relied on lipase-catalysed asymmetric process, and is summarized in Figures 6.10 and 6.11.12... 

Punaglandin 4 (208) is an example of a C-10 chlorinated prostanoid isolated from the Hawaiian octocoral telesto riisei. Its potent antitumor activity has attracted considerable synthetic interest. Characteristic of the a-chain is the same familiar dihydroxy stereochemistry found in (7, 7 )-tartaric acid. Wittig reaction of 167 with the phosphorane of [2-(l,3-dioxan-2-yl)ethyl]triphenylphosphonium bromide (205) followed by catalytic reduction and simultaneous debenzylation affords a primary alcohol, which is converted to aldehyde 206 in two oxidative steps. Aldol coupling of 206 with racemic cyclopentenone 207 (R=MOM) provides a statistical mixture of all four possible diastereomers. After chromatographic purification and protective group transformations, the target molecule 208 is obtained in 30—40% yield. The remaining three aldol products have been similarly converted to the diastereomers of 208 [75] (Scheme 47). 

Isol. from the Japanese octacoral Telesto riisei. 

C23H3,C10 M 438.947 Isol. from the Japanese octacoral Telesto riisei. Antitumour agent. 

Maia, L.E., Epifanio, R.A., and Fenical, W. (2000) New cytotoxic glycosides from the octocoral Carijoa Telesto) riisei. J. Nat. Prod., 63, 1427-1430. 

Some other cytotoxic amides formed between phenylethylamine, tyramine and fatty acids, with 12, 14 and 16 carbon atoms have been identified in the Telesto riisei (Telestacea) and Muricea austera (Gorgonacea). Some of them have considerable antimalarial activity (Gutierrez et al., 2006). 

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