KRISTIN R. ROWAN AND ELIZABETH M. HOLT 261 References Bossert, V. F., Horstmann, H., Meyer, H. & Vater, W. (1979). Arzneim. Forsch./Drug Res. 29, 226-229. Hayase, N., Itagaki, Y., Ogawa, S., Akutsu, S., Inagaki, S. & Abiko, Y. (1994). J. Pharm. Sci. 83, 532-538. Hurwitz, L., Partridge, L. D. & Leach, J. K. (1991). Calcium Channels: Their Properties, Functions, Regulation and Clinical Relevance. Boca Raton, Florida, USA: CRC Press. Loev, B., Goodman, M. M., Snader, K. M., Tedeschi, R. & Macko, E. (1974). J. Med. Chem. 17, 956-965. Ntinez-Vergara, L. J., Sunkel, C. & Squella, J. A. (1994). J. Pharm. Sci. 83, 502-507. Rodenkirchen, R., Bayer, R., Steiner, R., Bossert, F., Meyer, H. & Moeller, E. (1979). Naunyn-Schiedeberg's Arch. Pharmacol. 310, 69-78. Rowan, K. R. & Holt, E. M. (1995). Acta Cryst. C51, 2554-2559. Rowan, K. R. & Holt, E. M. (1996a). Acta Cryst. C52, 1565-1570. Rowan, K. R. & Holt, E. M. (1996b). Acta Cryst. C52, 2207-2212. Sadana, G. S. & Ghogare, A. B. (1991). J. Indian Chem. Soc. 68, 237-239. Sheldrick, G. M. (1990). Acta Cryst. A46, 467-473. Sheldrick, G. M. (1993). SHELXL93. Program for the Refinement of Crystal Structures. University of G0ttingen, Germany. Shibanuma, T., Iwanami, M., Fujimoto, M., Takenaka, T. & Mura- kami, M. (1980). Chem. Pharm. Bull. 28, 2609-2613. Siemens (1990). XP. Interactive Molecular Graphics Program. Ver- sion 4.1. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Siemens (1991). XSCANS Users Manual. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Squella, J. A., Zanocco, A., Perna, S. & Nfinez-Vergara, L. J. (1990). J. Pharm. Biomed. Anal. 3, 43-47. Triggle, D. J., Langs, D. A. & Janis, R. A. (1989). Med. Res. Rev. 9, 123-180. Acta Cryst. (1997). C53, 261-264 Triterpenoide. X.f U-ber neue isomere Triterpenlactone ANDRZEJ GZELLA, LucJusz ZAPRUTKOUND URSZULA WRZECIONO Lehrstuhl fiir Organische Chemie der K. Marcinkowski Universitiit der Medizinischen Wissenschaften Poznafi, ul. Grunwaldzka 6, 60-780 Poznafi, Polen (Eingegangen am 2. August 1996; angenommen am 15. Oktober 1996) Abstract The X-ray crystal structure analyses of three new triterpene lactones (C29H4206), namely 9/3-hydroxy-28- methoxy- 11,28-dioxo- 1,2-dinor- 10a, 18/3-olean- 12-en-3,- 10/3-olide, (3), and its 18c~- and 9a,18o~-isomers, (4) and (5) [9/3-hydroxy-28-methoxy- 11,28-dioxo- 1,2-dinor- 10a, 18c~-olean- 12-en-3,10/3-olide and 9a-hydroxy-28- methoxy- 11,28-dioxo- 1,2-dinor- 10a, 18a-olean- 12-en- 3,10/3-olide, respectively], are described. Compounds (3)-(5) were obtained by treatment of 3/3-hydroxy-1 l- i" Teil IX. Zaprutko (1995). © 1997 International Union of Crystallography Printed in Great Britain - all rights reserved oxo- 18a-olean- 12-en-28-oic acid methyl ester, (1), with sodium dichromate in acetic acid. In compounds (3)- (5), the six-membered ring A of (1) is replaced by a 3,-lactone ring. In contrast to compound (1), the C25 methyl group at C10 has an c~ configuration. The newly introduced hydroxyl group at C9 is/3 oriented in compounds (3) and (4), and a oriented in (5). Ring B in (3) has a boat form, but in (4) and (5) it has different equivalent chair conformations. Ring C in (3) has a sofa form, in (4), it has a slightly distorted half- chair form and in (5), it has a conformation intermediate between the half-chair and sofa forms. Rings D and E have chair conformations in all three compounds and are trans-fused in compounds (4), (5) and (1), and cis- fused in (3). In contrast to compound (1), rings A/B in compounds (3)-(5) and rings BIC in compounds (3) and (4) are cis-fused. In compounds (3)-(5), formation of hydrogen bonds has been observed. Inversion of the o~ configuration to a/3 configuration at C 18 in oleanolic acid derivatives [transformation of (1) to (3)] has been observed for the first time. The triterpene lactones (3)- (5) are the first known oleanane derivatives with cis- fused A/B [(3)-(5)] and B/C rings [(3) and (4)]. Kommentar Die Einwirkung von Natriumdichromat in Eises- sig auf 3/3-Hydroxy- 11-oxo- 18a-olean- 12-en-28-s~iure- methylester, (1), fiihrt neben dem bekannten 3- Oxo-derivat, (2) (Wrzeciono, Zaprutko, Budzianowski, W6jtowicz & Dubowska, 1987) zu drei weiteren iso- meren Verbindungen (3)-(5) mit der Summenformel C29H4206 (MS: M +" - 486). Aufgrund spektroskopi- scher Untersuchungen (IR, MS, 13C sowie 2D NMR) konnten die Strukturen dieser Verbindungen nicht ein- ,deutig aufgekl~Lrt werden. In dieser Mitteilung soil tiber o H,, 0 H -d ~ OOCH3 CH 3 (1) (2) (3) (4) (5) Acta Crystallographica Section C ISSN 0108-2701 © 1997