Kitungolides A, B, and C, New Diterpenes from a Soft Coral of a New Genus Liat Chill, † Amira Rudi, † Yehuda Benayahu, ‡ Michael Schleyer, § and Yoel Kashman* ,† School of Chemistry and Department of Zoology, Tel-AViV UniVersity, Ramat AViV 69978, Israel, and Oceanographic Institute, Durban, Republic of South Africa kashman@post.tau.ac.il Received December 18, 2003 ABSTRACT Three novel compounds, designated kitungolides A (1), B (2), and C (3), were isolated from a soft coral of a new genus collected at Kitungamwe, Kenya. The three new compounds are of a unique heterotricyclic skeleton. The structures and relative stereochemistry of the compounds were elucidated by interpretation of MS, COSY, HMQC, HMBC, and NOESY experiments. In the search for bioactive substances from marine inverte- brates, 1,2 three novel diterpenoids designated kitungolides A (1), 3 B(2), 4 and C (3) 5 were isolated from a Kenyan soft coral of a new genus. 6 All three compounds are of a unique heterotricyclic skeleton consisting of an unprecedented hexahydrocoumarine system. In this paper we present the isolation and structure determination of these novel marine metabolites. The CIMS of 1 exhibited a pseudomolecular ion [M + H] + at m/z 489. The molecular formula C 26 H 32 O 9 was * To whom correspondence should be addressed. Phone: +972-3-640- 8419. Fax: +972-3-640-9293. † School of Chemistry, Tel Aviv University. ‡ Department of Zoology, Tel Aviv University. § Oceanographic Institute. (1) Chill, L.; Aknin. M.; Kashman, Y. Org. Lett. 2003, 5, 2433-2435. (2) Rudi, A.; Chill, L.; Kashman, Y. J. Nat. Prod. 2003, 66, 575-577. (3) Kitungolide A (1): an oil; [R] 21 D +36.5° (c 0.71, CHCl3); for 1 H and 13 C NMR data, see Table 1; CIMS m/z 489 [M + H] + , 429 [M + H - Ac] + (15), 369 [M + H - 2Ac] + (90), 327 (95), 309 [M + H - 3Ac] + (100), 277 (45), 259 (30); HRCIMS m/z 489.2124 (calcd for C26H33O9, 489.2126, ∆ ) 0.1 ppm). (4) Kitungolide B (2): an oil; [R] 21 D +70.6° (c 0.11, CHCl3); for 1 H and 13 C NMR data, see Table 1; CIMS m/z 345 [M + H] + (60), 327 [M + H - H2O] + (100), 301 (90), HRCIMS m/z 345.1702 (calcd for C26H32O9, 345.1702, ∆ )-0.1 ppm). (5) Kitungolide C (3): an oil; [R] 21 D +54.5° (c 0.07, CHCl3); for 1 H and 13 C NMR data, see Table 1; CIMS m/z 345 [M + H] + (60), 327 [M + H -H2O] + (100), 301 (90), HRCIMS m/z 345.1699 (calcd for C26H32O9, 345.1702, ∆ ) 0.8 ppm). (6) For description of the coral, see Supporting Information. ORGANIC LETTERS 2004 Vol. 6, No. 5 755-758 10.1021/ol036454t CCC: $27.50 © 2004 American Chemical Society Published on Web 02/05/2004