| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1997: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1996: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Research Abstract |
This project aimed to synthesize various natural products by the extensive use of microbial reduction as the chirality induction method.
1. Enantioselective synthesis of octalactin A exhibiting potent cytotoxic activity was investigated. Starting from (-) -citronellol, an efficient route for the synthesis of Buszek's intermediate was developed by the use of baker's yeast reduction, asymmetric dihydroxylation, and stereoselective hydroboration.
2. A new and highly effective method for the conversion of primary alcohols into terminal olefins was developed. The method involves simple treatment of benzyl ethers of primary alcohols with n-BuLi and the corresponding terminal olefins are obtained in high yield. The reaction was successfully applied in the synthesis of octalactin A.
3. Quassiol A is an acyclic triterpene ether having five chiral centers whose absolute configuration has not been determined. By using yeast reduction as the chirality induction method, three diastereomers were synthesized enantioselectively. On the basis of spectral properties and optical rotations, the absolute structure of natural quassiol A was proposed.
4. Enantioselective synthesis of eurylene, an acyclic triterpene ether having eight chiral centers, was studied. From the same compound obtained by the asymmetric reduction with baker's yeast, two C_<15>-segments was synthesized simultaniously. The coupling of these segments is currently under proceeding.
5. Synthesis and the determination of absolute stereostructure of hippospongic acid, an irregular triterpenoid which inhibits the gastrulation of starfish potently, were examined. The synthetic route starting from myrcene has been established by the synthesis of racemic compound. The synthesis of optically active compound using yeast reduction as a key step is now at the final stage.
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