Organic Letters
Letter
Notes
Scheme 4. Synthesis of the C15−C38 Fragment 2
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We thank Professor Keiichi Konoki (Graduate School of
Agricultural Science, Tohoku University) for his fruitful
discussions and encouragement. This work was supported in
part by a Grant-in-Aid for Scientific Research on Innovative
Areas “Chemical Biology of Natural Products” from the
Ministry of Education, Culture, Sports, Science and Technol-
ogy (MEXT), Japan.28
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imidazole provided the alcohol 23 (89%). Dess−Martin
oxidation26 (94%) followed by methylenation with Tebbe
reagent27 afforded the C15−C38 fragment 2 (99%).
In conclusion, we have developed a concise synthetic entry to
the C15−C38 fragment 2 of okadaic acid by exploiting Suzuki−
Miyaura reaction for the synthesis of the spiroacetal
substructures. Our synthetic strategy allows for rapid assembly
of complex spiroacetals in high yield. The present synthesis of 2
requires just 19 linear steps from a commercially available
material and thus compares favorably with the previous work by
other groups. This work sets the stage for the development of
elaborated synthetic analogues of okadaic acid to elucidate the
SAR and biological activity in detail. Work along this line is
currently in progress.
ASSOCIATED CONTENT
* Supporting Information
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S
Experimental details and copies of 1H and 13C NMR spectra of
all new compounds. This material is available free of charge via
AUTHOR INFORMATION
Corresponding Author
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(9) Ley, S. V.; Humphries, A. C.; Eick, H.; Downham, R.; Ross, A. R.;
Boyce, R. J.; Pavey, J. B. J.; Pietruszka, J. J. Chem. Soc., Perkin Trans. 1
1998, 3907−3911.
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