On the friedelene-oleanene rearrangement
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Cited by (19)
Occurrence of triterpenyl acetates in soil and their potential as chemotaxonomical markers of Asteraceae
2011, Organic GeochemistryCitation Excerpt :Pentacyclic triterpenes are reputed to suffer structural rearrangements and double bond migration during diagenesis that could affect the original diversity of compounds (e.g. Rullkötter et al., 1994). This phenomenon, well documented from laboratory experiments for compounds the oleanane series (Courtney et al., 1958; Coates, 1967), is also observed in sedimentary records (Rullkötter et al., 1994). Precisely, friedel-3-ene, glutin-5-ene, multiflor-7-ene and taraxer-14-ene are progressively rearranged to olean-18-ene, olean-12-ene and finally olean-13(18)-ene isomers.
Pentacyclic triterpene methyl ethers in recent lacustrine sediments (Lagoa do Caçó, Brazil)
2005, Organic GeochemistryEarly diagenetic transformation of organic matter in a marine-influenced lignite
2003, Organic GeochemistryCitation Excerpt :However, the ratio of olean-12-ene to its rearranged isomers varies over the depth profile (Table 3), perhaps related to varying acidity within the parent peat, but most probably due to specific input or depletion of one or more of the isomers. Contributions to the oleanenes could also arise from the acid-catalysed rearrangement of friedelane (XXVIII) derivatives (Courtney et al., 1958; Coates, 1967; Chatterjee et al., 1976; Ageta et al., 1987) while lup-20(29)-ene (XXIV) may undergo ring E expansion under similar conditions to afford a series of oleanene and taraxastene (XXVII) isomers (Perkins et al., 1995). Therefore, the only sulfur-bound triterpanes that are singularly derived from natural products bearing the same carbon skeleton (i.e. non-rearranged) are lupane (XXVI) and friedelane (XXVIII).
Occurrence of 28-nor-18α-oleanane in the hydrous pyrolysate of a lignite
1995, Organic GeochemistryEarly diagenesis of terrigenous triterpenoids and its implications for petroleum geochemistry
1994, Organic GeochemistryEarly diagenetic transformation of higher-plant triterpenoids in deep-sea sediments from Baffin Bay
1992, Geochimica et Cosmochimica Acta