31 ヒノキフラボンの合成
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概要
- 論文の詳細を見る
The structure of hinokiflavone was confirmed by synthesis. Permethylated 3-nitrobisapigenyl ether (XVI), the key-intermediate for the synthesis, was prepared by the condensation of 8-hydroxy-4',5,7-trimethoxyflavone (XIV) with 4'-iodo-3'-nitro-5,7-dimethoxyflavone (XV) in DMSO in the presence of K_2CO_3 at 110℃ for 1hr. The nitro ether was reduced by Na_2S_2O_4 in aq. DMF, diazotized and decomposed with 50% H_3PO_2 to give 4'",5,5",7,7"-pentamethoxy-4',8"-bisapigenyl ether (XVIII), different from pentamethyl ether of natural hinokiflavone. An alternative bisflavone with 4',6"-coupling positions has now been synthesized in a similar route described above. 6-hydroxy-4',5,7-trimethoxy flavone (XXVIII) was condensed with 4'-iodo-3' nitroflavone (XV) to 3'-nitro ether (XXIX), which was reduced, diazotized and decomposed to give permethylated ether (XXXI). The latter proved to be identical in m.p., mixed m. ps. and IR spectra with permethyl ether of natural hinokiflavone. The synthesized methyl ether was finally demethylated by means of HI・Ac_2O at 130〜140℃ for 3hrs. to give 4'",5,5",7,7"-pentahydroxy-4',6"-bisapigenyl ether (XX) identical with natural hinokiflavone. 4'-8"-Bisflavone (XVIII) was converted into a bisflavone (XX) identical with natural hinokiflavone, when heated with HI・Ac_2O as above, under conditions which may be expected to bring about the Wessely-Moser rearrangement in flavones, coumarins, xanthones etc.
- 天然有機化合物討論会の論文
- 1967-09-25