Bicycloelemanes, Bicyclogermacranes and Vitranes

Some Porella species contain (—)-bicyclogermacrene (228), together with e r-gurjunenes (33, 35) and e r-cyclocolorenones (38, 39) (59). Compound (228) cooccurs together with aromadendranes (34, 38—42), 2,3-secoaromadendranes (45—54, 56—60) and maalianes (455, 458, 459) in most Plagiochila species 21, 64). Chiroptical properties of (228) are opposite to those found for the same compound in the peel oil of Citrus species 273, 274). 

Chart 7. Bergamotanes, bicycloelemanes, bicyclogermacranes, and vitranes found in the 

The stereostructure of (—)-isobicyclogermacrenal (230) isolated from Lepidozia vitrea was determined by comparing the H-NMR spectrum with the spectra of bicyclogermacrenes (228) and (230) 215). The geometries of two double bonds of (230) were based on NOE experiments. The absolute configuration was established by the preparation of a methyl ester (70) derived from (—)-taylorione (61) 242—244). 

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