著者

石井 永 石川 勉 小林 純一 関 宏子

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.34, pp.518-525, 1992-09-10

---

Toddacoumalone (4) and toddacoumaquinone (5), isolated from Toddalia asiatica (L.) Lam. (T. aculeata Pers.) (Rutaceae), were established to be novel unique mixed dimers based on a coumarin by spectroscopic means mainly 2D-NMR. Toddacoumalone (4), C_<31>H_<31>NO_6, was isolated as colorless prisms, mp 202-204℃ (AcOEt), in a racemic form. Its IR, UV, and NMR (Table 1) spectra including the COLOC experiment based on three bond correlations (Table 2) indicated the presence of a 8-substituted 5, 7-dimethoxycoumarin like 6 and an N-methyl-2-quinolone like 7 in 4. A monoterpene bridge of CH=CHC(Me)CH_2CHCH=CMe_2 with cis arrangement between the two vinyl groups was interposed between the coumarin and the quinolone units. Though lack of coupling between the conjugated olefinic protons gave us no clue to the geometry, an E geometry for the double bond could be deduced by appearance of conjugated (E)-olefinic protons in toddalenol (12) as a 2H singlet and coexistence of toddasin (13) in the same plant. Connection of the C_<10> unit to the coumarin and the quinolone systems resulted in drawing the structure of 4 for toddacoumalone. Toddacoumaquinone (5), C_<23>H_<18>O_7, was isolated as orange prisms, mp 278-281℃ (AcOEt). The same 8-substituted 5, 7-dimethoxycoumarin moiety was also found to be in 5. In this case presence of an 8-substituted 2-methoxy-6-methyl-p-naphthoquinone system was reasonably deduced by spectral data. Thus, toddacoumaquinone should be a biaryl compound consisting of a coumarin and a naphthoquinone, the structure of which could be depicted as 5. Both the dimers would be synthesized in a plant body through Diels-Alder type cycloaddition reaction. The synthetic works based on this biogenetic consideration are now in progress.