1 カミエビ葉中の殺虫性アルカロイド,Cocculolidineの構造

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A new insecticidal alkaloid, cocculolidine, C_<15>H_<19>O_3N, mp. 146℃, has been isolated from the fresh leaves of Cocculus trilobus DC. through the solvent extractions and subsequent chromatography on alumina (the yield 0.007-0.03%). This report presents evidence which let us assign the structure (I) for cocculolidine. The tertiary nitrogen atom was proved from the ready formation of the methiodide and absence of NH absorption in the infrared spectrum. The spectral data for cocculolidine showed the presence of α,β-unsaturated lactone, a methoxy group and a trisubstituted double bond. The base peak (M-58) in the mass spectrum and the half-height width (24 c.p.s.) of the signal of CH_3O-C-H of (I) suggested the presence of the partial structure (b). Reduction of (I) with NaBH_4 in MeOH gave (II). It was further hydrogenated with PtO_2 in AcOH to the saturated compound (III). Thus, (I) was concluded to be a tetracyclic compound. Oxidation of (II) with KMnO_4 in acetone-H_2O produced γ-lactam (IV). The above data led to the partial structures (b), (c), (d), and (e) for (I). The relationship between the partial structures was elucidated by BrCN reaction. (I) was treated with BrCN to give C-15 cyanamide (VII). The molecular formula, C_<15>H_<14>O_2N_2 and λ^<MeOH>_<max> ; 255mμ (ε=1850), 275mμ, (e=540) of (VII) showed the occurence of the aromatization accompanied by dehydrobromination and loss of methanol during this reaction and the presence of the sterically hindered o-substituted styrene in C-15 cyanamide. From the above data and the n.m.r., C-15 cyanamide was assigned to the structure (VII). Further chemical evidence about the relationship between the cyclohexene ring and the nitrogen in (I) was obtained by the product (VIII) of the acid catalyzed rearrangement. From the above data, cocculolidine was assigned to the structure (I).
天然有機化合物討論会の論文
1966-09-15

1 カミエビ葉中の殺虫性アルカロイド,Cocculolidineの構造

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