Figure 5 | Scientific Reports

Figure 5

From: Rapid encapsulation of true ferns and arborane/fernane compounds fossilised in siderite concretions supports analytical distinction of plant fossils

Figure 5

(A) Simplified mechanism of formation of C30 αβ-hopane (VI) and derivatives from diplopterol (I) and diploptene (II) precursors (structures in grey represent precursors and intermediates, structures in black are identified in samples from this study). (B) Proposed mechanism by Vliex et al.7 of formation of compounds MATH (IX), MAPH (X), DAPH-1 (XI) and DAPH-2 (XII), from fern-9(11)-en-3β-ol (XIII) and arbor-9(11)-en-3β-ol (XIV). Derivatives are shown with an arborane isomeric configuration, although both would be possible, for ease of demonstration. (C) Simplified mechanism showing possible formation of D-ring monoaromatic 8,14-secohopane (XV), hop-17(21)-ene (XX) and MATH (IX) from the fernene isomers (III, IV, V).

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