Plagiochilin

A continuing investigation of the sesquiterpenoids from liverworts (Plagiochila species) has revealed the presence of more seco-aromadendrane compounds, namely plagiochilines A (652), B (653), C (654), D (655), E (656), and F (657). Plagiochilide (658) has been found in the Swiss species of P. asplenioides but not in the French version. The presumed precursor of these compounds, (-)-bicyclogermacrene (659), has also been identified in the extracts... 

Chemical and spectroscopic evidence has been provided to support the seco-aromadendrane structures assigned to plagiochilide (621) and plagiochiline A (622). ... 

An examination of the sesquiterpenoid constituents of the liverwort Plagiochila semidecurrens has resulted in the isolation of ovalifoliene (=plagiochiline C) (671), hanegokidial (672), and ovalifolienalone (673). A related and wide ranging investigation of other Plagiochila species... 

Plagiochiline A (104) that shows potent insect antifeedant, cytotoxicity, and piscidal activity are very pungent 2,3-secoaromadendrane sesquiterpenoids having 1,1-dimethyl cyclopropane ring, isolated from the liverwort Plagiochilafruticosa. Plagiochilide (105) is the major component of this liverwort. In order to get more pungent component, the lactone (105, 101 mg) was incubated with... 

LiAlH4/Et20 2) Ha/PtOj/EtOAc Scheme 5. Reactions of plagiochiline A... 

Further study of the 2,3-secoaromadendrane-type sesquiterpenoids of European Plagiochila species resulted in isolation of plagiochilines C (= ovalifoliene) (48), D (49), E (50) and F (51) 71). The stereostructures of the highly acetylated compounds (49—51) were elucidated mainly by comparison of their H-NMR spectral data with those of plagiochilines A (46) and B (47). Matsuo and his coworkers 209) reported isolation of plagiochiline C whose structure (48) was based on analysis of the NMR spectrum and on chemical degradation (Scheme 7). 

LiAlH4/Et20 2) CrOa-Py 3) Os04-NaI04 Scheme 7. Reactions of plagiochiline C... 

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