14 セファランチンを中心としたビスベンジルイソキノリン型アルカロイドの化学における新展開

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I) In order to prepare whole-body autoradiograms of experimental animals after drug administration, [methylenedioxy-^<14>C] cepharanthine was prepared. Cepharanthine was treated with BCl_3 in CH_2Cl_2 to give demethylenated cepharanthine in good yield. After non-radioactive experiments, treatment of three molar demethylenated cepharanthine with CsF and ^<14>CH_2I_2 in DMF gave [methylenedioxy-^<14>C]cepharanthine quantitatively. (The yield was calculated based on ^<14>CH_2I_2). II) The structures of four new secobisbenzylisoquinoline alkaloids (Base J, Base K, Base B, and Base C) which were naturally occurred in Stephania sasakii (Menispermaceae) were established. Secocepharanthine (Base J) and O-methylpunjabine (Base K) were derived by controlled oxidation of cepharanthine and of isotrilobine, respectively, including a sign of optical rotation. Treatment of secocepharanthine with NaBH_4 gave dihydrosecocepharanthine (Base B). Wolff-Kishner reduction of O-methylpunjabine gave O-methyldeoxopunjabine (Base C). III) The bisbenzylisoquinoline alkaloids belong to a type of oxyacanthine-berbamine are subdivided into oxyacanthine- (cis O_4-O_4), repandine- (trans O_4-O_4), berbamine- (cis O_5-O_3), and tetrandrine- (trans O_5-O_3) groups. In order to examine the effect of their conformations in an eighteen membered ring to reaction behavior in detail, their PMR and ^<13>C-NMR spectra were systematically measured. Following conclusions will be discussed: The oxyacanthine type alkaloids (cis O_4-O_4) bearing a methoxy group at C_7 position are present as atropisomers between 8,7'-biaryl ether in a CHCl_3 solution at room temperature. In all of these four type alkaloids, their N-methyl groups at the N_<(2)> position were situated in axial. In the PMR spectrum, the signal due to the C_<10>,-aromatic proton appeared in the high field, around δ 5.5. The assignment of signals in the ^<13>C-NMR spectra of these alkaloids will be shown.
天然有機化合物討論会の論文
1983-09-15

14 セファランチンを中心としたビスベンジルイソキノリン型アルカロイドの化学における新展開

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