Marine Terpenes and Terpeoids. IX

• Published in: Chemical & pharmaceutical bulletin Vol. 37; no. 8; p. 2053
• Main Authors: KOBAYASHI, Masaru, IESAKA, Takako, NAKANO, Emiko
• Format: Journal Article
• Language: English
• Published: Tokyo Japan Science and Technology Agency 01.08.1989
• ISSN: 0009-2363; 1347-5223

The structures of six cembranoids, sarcophytol P (3a), sarcophytol R (4), sarcophytol S (5), sarcophytol Q (8a), sarcophytol K (11a), and sarcophytol F (14a), isolated from the soft coral Sarcophyton glaucum, were determined from the spectroscopic properties and by synthesis, or by analyses of their derivatives formed on storage in CHCl3. Sarcophytol P (3a) was shown to be the 20-hydroxy derivative of the major component sarcophytol A (1a), and afforded the transannular cyclization product 6 on storage in CHCl3 at room temperature, in the same way as 1a. Sarcophytol R (4) and sarcophytol S (5) were correlated to 1a by conversion of its 7R, 8R (7a) and 7S, 8S (7b) epoxide derivatives. Sarcophytol Q (8a) was shown to be a 1, 4, 14-trihydroxycembranoid, and was converted to the known ring-cleaved aldehyde 9. Sarcophytol K (11a) was a 13, 14-dihydroxycembranoid having a 1E, 3Z-diene moiety. The absolute configurations of 11a and its 1Z, 3E- and 1Z, 3Z-isomers sarcophytols B (2a) and J (13a) were determined by a circular dichroism study of their bis-p-dimethylaminobenzoate derivatives. Sarcophytol F (14a) was a 1E isomer of 1a and showed characteristic proton nuclear magnetic resonance spectral properties due to the restricted conformational interconversion. The structure was derived by characterizing two decomposition products, the same pentaene (15) and dihydrofuran (17) derivatives as those derived from 1a.