H. Takamura et al. / Tetrahedron Letters 50 (2009) 863–866
865
Figure 3. 800 MHz 1H NMR spectra of bis-MTPA esters in CDCl3: (a) bis-(S)-MTPA ester derived from natural 1, (b) synthetic bis-(S)-MTPA ester, (c) bis-(R)-MTPA ester
derived from natural 1, (d) synthetic bis-(R)-MTPA ester.
Nakamura, H.; Asari, T.; Murai, A.; Kan, Y.; Kondo, T.; Yoshida, K.; Ohizumi, Y. J.
Am. Chem. Soc. 1995, 117, 550; (d) Nakamura, H.; Asari, T.; Fujimaki, K.;
Maruyama, K.; Murai, A.; Ohizumi, Y.; Kan, Y. Tetrahedron Lett. 1995, 36, 7255;
(e) Nakamura, H.; Fujimaki, K.; Murai, A. Tetrahedron Lett. 1996, 37, 3153; (f)
Nakamura, H.; Sato, K.; Murai, A. Tetrahedron Lett. 1996, 37, 7267; (g)
Nakamura, H.; Takahashi, M.; Murai, A. Tetrahedron: Asymmetry 1998, 9,
2571; (h) Nakamura, H.; Maruyama, K.; Fujimaki, K.; Murai, A. Tetrahedron Lett.
2000, 41, 1927.
In conclusion, we obtained the C33–C42 fragment 4 by cross-
metathesis degradation of 2 with ethylene. The absolute stereo-
chemistry of 4 was estimated by Mosher method. The proposed
structure including absolute configuration was unambiguously
confirmed by the enantio- and stereocontrolled synthesis of 4 in
14 steps from L-aspartic acid. Further structural and synthetic stud-
ies on 1 are underway in our laboratories.
3. Takamura, H.; Ando, J.; Abe, T.; Murata, T.; Kadota, I.; Uemura, D. Tetrahedron
Lett. 2008, 49, 4626.
4. For some examples of the degradation of natural products by cross-metathesis,
see: (a) Ratnayake, A. S.; Hemscheidt, T. Org. Lett. 2002, 4, 4667; (b) Niggemann,
J.; Bedorf, N.; Flörke, U.; Steinmetz, H.; Gerth, K.; Reichenbach, H.; Höfle, G. Eur.
J. Org. Chem. 2005, 5013; (c) Williams, P. G.; Miller, E. D.; Asolkar, R. N.; Jensen,
P. R.; Fenical, W. J. Org. Chem. 2007, 72, 5025.
5. Garber, S. B.; Kingsbury, J. S.; Gray, B. L.; Hoveyda, A. H. J. Am. Chem. Soc. 2000,
122, 8168.
6. Structural determination of other degraded products obtained by cross-
metathesis will be reported in the near future.
Acknowledgments
We thank Okayama Foundation for Science and Technology and
The Naito Foundation for their financial supports. This research
was partially supported by Grant-in-Aid for Scientific Research
from MEXT, Japan.
7. Ohtani, I.; Kusumi, T.; Kashman, Y.; Kakisawa, H. J. Am. Chem. Soc. 1991, 113,
4092.
References and notes
8. For determination of the absolute stereochemistry of secondary/secondary
diols by Mosher method, see: Freire, F.; Seco, J. M.; Quiñoá, E.; Riguera, R. J. Org.
Chem. 2005, 70, 3778.
1. Kita, M.; Ohishi, N.; Konishi, K.; Kondo, M.; Koyama, T.; Kitamura, M.; Yamada,
K.; Uemura, D. Tetrahedron 2007, 63, 6241.
9. Bis-(S)-MTPA ester: 1H NMR (800 MHz, CDCl3) d 7.50 (m, 4H, Ph), 7.39 (m, 6H,
Ph), 5.76 (ddd, J = 17.0, 10.6, 7.3 Hz, 1H, H41), 5.68 (dt, J = 8.7, 6.4 Hz, 1H, H36),
5.58 (m, 1H, H34), 5.56 (m, 1H, H40), 5.33 (d, J = 17.0 Hz, 1H, H42a), 5.24 (d,
J = 10.6 Hz, 1H, H42b), 5.23 (m, 1H, H37), 5.01 (dt, J = 17.0, 1.4 Hz, 1H, H33a),
5.00 (m, 1H, H33b), 3.53 (s, 3H, OCH3), 3.52 (s, 3H, OCH3), 2.45 (dd, J = 13.3,
6.0 Hz, 1H, H39a), 2.36 (m, 1H, H35a), 2.31 (dd, J = 13.3, 7.8 Hz, 1H, H39b), 2.26
2. Symbiodinolide (1) is a structural congener of zooxanthellatoxins which are
polyol macrolides isolated from the dinoflagellate Symbiodinium sp. For the
structural elucidation of zooxanthellatoxins, see: (a) Nakamura, H.; Asari, T.;
Murai, A.; Kondo, T.; Yoshida, K.; Ohizumi, Y. J. Org. Chem. 1993, 58, 313; (b)
Asari, T.; Nakamura, H.; Murai, A.; Kan, Y. Tetrahedron Lett. 1993, 34, 4059; (c)