64(P38) 環状糖脂質Calonyctin Aの合成研究(ポスター発表の部)

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Calonyctin A, isolated from Calonyction aculeatum L. House, has a potent prompting effect on the growth of various plants. Calonyctin A is a glycolipid having aglycon of fatty acids with different chain length which form a unique 22-membered macrolide structure. In order to determine the structure of Calonyctin A and to get information about structure-activity relationship, total synthesis of a short-chain component of Calonyctin A1 was carried out. The aglycon moiety of 1, optically active 9-hydroxy-myristic acid 2, was planed to be synthesized from L-glutamic acid 6 and 1,9-nonanediol. Thus, the former was transformed to the C_5-epoxide 12, and the latter was converted into the bromide 13. Coupling of 12 and 13 was performed using a CuI-catalyzed Grignard reaction to give the tetradecane 14. One primary hydroxyl group of 14 was reduced in a 3-step reaction including desilylation, bromination, and radical reduction. The product 18 was converted into the methyl ester 20 employing TEMPO oxidation as a key reaction. For the construction of the tetrasaccharide moiety of 1, laminaribiose was used as a precursor of the most complicated core β-(1,3)-linked disaccharide moiety to shorten the synthetic scheme. Treatment of phenyl 1-thio-β-laminaribioside 23 with an excess of α,α-dimethoxytoluene in presence of camphorsulfonic acid gave the unusual tribendylidene derivative 24 having an eight-membered ring. 24 was underwent allylation followed by selective acid-hydrolysis to give the 2,2'-diol 27. Reductive ring opening of a diacetate derived from 27 with borane trimethylamine complex-aluminum chloride gave a 4,4'-di-O-bendylate 29, which was used for the glycosidation after conversion to the 6,6'-mesylate 3. Other two monosaccharide intermediates (4 and 5) were prepared from D-glucose and L-Rhamnose by normal procedures. Coupling of the four synthons and formation of the macrolactone ring were under way.
天然有機化合物討論会の論文
1997-07-20

64(P38) 環状糖脂質Calonyctin Aの合成研究(ポスター発表の部)

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