Steranes rearranged

The steranes are a class of biomarkers containing 21 to 30 carbons that are derived from sterols, and they include regular steranes, rearranged diasteranes, and mono-aromatic and tri-aromatic steranes. Among them, the regular C27-C28-C29 homologous sterane series are the most common and useful steranes because they are highly specific for correlation. The concentrations of C29 steranes (24-ethylcholestanes) compared to the C27 and C2g-steranes may indicate a land plant source. 

Rubinstein I., Sieskind O., and Albrecht P. (1975) Rearranged steranes in a shale occurrence and simulated formation. J. Chem. Soc. Perkin Trans. 1, 711-719. 

Fig. 5. 35 Possible origin of 20S and 2044 epimers of 14(1.17 )-stcrancs in immature sediments from A7 stenols. Note the A14 (2044 -17 -sterene intermediates can give rise to (2044)-14a,17cx-steranes upon reduction, as an alternative to undergoing rearrangement to spirosterenes (large arrow indicates biogenic input after Peakman Maxwell 1988 Peakman et al. 1989).

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