53 Herbimycin及びElasninの構造^<13>C-nmrを用いる生合成的手段の併用

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The structural elucidation of herbimycin (1), C_<30>H_<42>N_2O_9, which exhibits a strong herbicidal activity and elasnin (4), C_<24>H_<40>O_4, which is a new specific inhibitor of human granulocyte elastase have been carried out based on spectral analyses, chemical degradations and biosynthetic means using ^<13>C-labeled precursors. From the ^1H and ^<13>C-nmr spectral analyses of 1, it was found to be structurally similar to geldanamycin (2), an ansamycin antibiotic containing a benzoquinone as a chromophore. The arrangement of the partial structures A, C, D and E which were proposed from the nmr spectral analyses of 1 and 3 was established from the incorporation of [1-^<13>C]propionate to 1. The ^<13>C-nmr spectrum of 4 suggests the existence of four linear C_4 and C_5 alkyl chains in 4. The chemical transformation of 4 into γ-pyrone (9) and isoxazole derivative (10) and the spectral evidence for 4 deduced high-alkylated hydroxy-α-pyrone for the structure of 4. Furthermore, the structural correlation between tautomeric isomers, 4 and its methyl ether 11, was determined from ^<13>C-^<13>C coupling in the ^<13>C-nmr spectrum of elasnin labeled with [1,2-^<13>C]acetate. Consequently, it was found that the methylation of 4 brings about the structural change from α-pyrone to γ-pyrone.
天然有機化合物討論会の論文
1979-09-20