Coreximine 関連化合物の合成研究(第5報) : (±)-Tetrahydropalmatine の全合成ならびに Halogen 置換異常反応について複素環式化合物の合成研究第194報

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During debenzylation of the compound (I) with an ethanolic hydrochloric acid solution, substitution of bromine with chlorine was found to give a mixture of 2'-bromo- and 2'-chloro-compounds (II). This fact was revealed by total synthesis of (±)-tetrahydropal-matine (V). The Mannich reaction of the above mixture (II) with formaldehyde, followed by methylation with diazomethane, afforded a mixture of 12-halogenoprotoberberines (IV), whose reduction with zinc in alkaline solution gave a mixture of (±)-tetrahydropalmatine (V) and its 12-chloro-compound (VI). By thin-layer chromatography, the former compound was separated and found to be identical with an authentic sample from spectral measurement and mixed melting point test. On the other hand, the 12-chloro-compound (VI) was also characterized by comparison with an authentic sample prepared by the following method. Bischler-Napieralski cyclization of the amide (XII), obtained by fusion of phenethylamine (XI) with the ester (X), gave the 3,4-dihydroisoquinoline compound (XIII). Reduction of XIII with sodium borohydride, followed by debenzylation of the resultant 1,2,3,4-tetrahydroisoquinoline (XIV), afforded the phenolic base (XV), which was cyclized by the Mannich reaction with formaldehyde to give the 12-chloroprotoberberine (XVI). Methylation of XVI with diazomethane gave the same compound (VI) as above. Furthermore, comparison of the NMR spectra of the reaction mixture while heating 2-bromo-compound (XVII) with hydrochloric acid revealed that it was converted into the 2-chloro-compound (XVIII) in proportion to the time of heating increases. After 48 hours' heating, the formation of XVIII was found to be characterized as follows. Methylation of XVIII afforded the expected compound (XIX), identical with an authentic sample.
社団法人日本薬学会の論文
1967-09-25

Coreximine 関連化合物の合成研究(第5報) : (±)-Tetrahydropalmatine の全合成ならびに Halogen 置換異常反応について複素環式化合物の合成研究第194報

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Coreximine 関連化合物の合成研究(第5報) : (±)-Tetrahydropalmatine の全合成ならびに Halogen 置換異常反応について 複素環式化合物の合成研究 第194報

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Coreximine 関連化合物の合成研究(第5報) : (±)-Tetrahydropalmatine の全合成ならびに Halogen 置換異常反応について複素環式化合物の合成研究第194報