99(P-56) 海洋産アルカロイドHaliclorensinの合成研究(ポスター発表の部)

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Haliclorensin 1, a novel diamino alkaloid possessing an aza-cyclodecane ring, has been isolated from the sponge, Haliclona tulearensis by Kashman et al. in 1998. The structure of the alkaloid was proposed from spectroscopic data. Furthermore haliclorensin forms part of the structure of halitulin 2, a more complex bisquinolylpyrrole alkaloid from the same organism that exhibits strong cytotoxic activity against mouse leukemia cell. The unique structure as well as the significant biological activities led us to undertake the enantioselective synthesis of haliclorensin. Our synthetic strategy of haliclorensin involves regio-selective photochemical rearrangement of spirocyclic oxaziridines into lactams. Oxaziridine 8 derived from cyclononanone and (R)-phenylethylamine was irradiated with a low-pressure lamp (254nm) in benzene at rt to afford the corresponding lactam 9 in 54% yield. Methylation of 9 with LDA/MeI afforded 10 in 70% yield as a 4: 1 mixture of two diastereomers. Other chiral amines were screened with intend to optimize the diastereoselectivity. Lactam 14 derived from cyclononanone and the methyl ether of (R)-phenylglycinol was methylated with sec-BuLi/MeI to give the desired product 16 in 62% yield as a 9: 1 mixture of two diastereomers. Further synthetic studies directing toward the proposed structure of 1 is now in progress. Recently the total synthesis of the structure proposed for haliclorensin has been reported. The ^<13>C NMR data and optical rotation of the synthetic compound differ from the values given for haliclorensin. We also have been reexamining the spectroscopic data reported by Kashman to revise the structure of haliclorensin.
天然有機化合物討論会の論文
2001-09-01

99(P-56) 海洋産アルカロイドHaliclorensinの合成研究(ポスター発表の部)

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