2,3-Secoaromadendrane sesquiterpenoids

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... 

Taylorione (683), an unusual ent-l,10-secoaromadendrane sesquiterpenoid from the leafy liverwort Mylia taylorii, has been synthesized from (+)-A -carene. ... 

Furusawa, M., T. Fiashimoto, Y. Noma, and Y. Asakawa, 2006a. Biotransformation of aristolene- and 2,3-secoaromadendrane-type sesquiterpenoids having a 1,1-dimethyicyciopropane ring by Chlorella fusca var. vacuolata, Mucor species, and Aspergillus niger. Qienh ham 54 861-868. 

Aromadendrane-type sesquiterpenoids are mainly distributed in Mylia, Plagiochila and Porella species belonging to the Jungermanniales. 2,3-Secoaromadendrane-type sesquiterpenoids have been isolated only from the Plagiochilaceae. A Mylia species contains a unique 1,10-secoaromadendrane-type sesquiterpene. 

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). 

More than 1500 species of Plagiochila species are known world wide. The distribution of sesquiterpenoids in 14 Plagiochila species has been reported and e -2,3-secoaromadendrane-type sesquiterpenoids are now recognized as common constituents of Plagiochila species, except in a few species (27). These and related sesquiterpenoids might be formed from (—)-bicyclogermacrene (228) which is a co-metabolite of Plagiochila species, by the routes shown in Scheme 12 68). 

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