Nature 256, 301 - 302 (24 July 1975); doi:10.1038/256301a0

Stereochemistry of some steranes from geological sources

L. J. MULHEIRN & G. RYBACK

Shell Research Limited, Milstead Laboratory, Sittingbourne Research Centre, Sittingbourne, Kent, ME9 8AG, UK

THE steranes present in crude oils and sedimentary rocks are believed to be derived from the sterols of ancient organisms. Their precise structure and stereochemistry may give important clues about the nature of the original biological materials and about the geochemical processes which they have undergone. Examination of synthetic steranes^1,2 has led us to question the adequacy of reported³⁻⁶ identifications, using only gas−liquid chromatography (GC) and mass spectroscopy (MS), of steranes such as 5-cholestane, 5-ergostane, and 5-stigmastane ( =5-sitostane) in geological samples. The last two, in particular, seem incompletely identified, since the configuration at C-24 has been ignored (although it is of phylogenetic importance in modern organisms^7,8), and since we find that epimers at C-24, that is II and III, IV and V, are indistinguishable using GC and MS. The use of the names 5-ergostane and 5-stigmastane in geochemical work both for steranes of undetermined configuration at C-24 and for synthetic samples of defined configuration is confusing. In the absence of clear IUPAC/IUB rules, we have adopted the names shown in Fig. 1.

References

1.	Mulheirn, L. J., Tetrahedron Lett., 3175–3178 (1973).
2.	Mulheirn, L. J., and Ryback, G., J. chem. Soc. Chem. Comm., 886–887 (1974).
3.	Hills, I. R., Smith, G. W., and Whitehead, E. V., J. Instn Petrol., 56, 127–137 (1970).
4.	Ikan, R., and Bortinger, A., Israel J. Chem., 9, 679–682 (1971).
5.	Gallegos, E. J., Analyt. Chem., 43, 1151–1160 (1971).
6.	Maxwell, J. R., Pillinger, C. T., and Eglinton, G., Q. Rev. chem. Soc., 25, 571–628 (1971).
7.	Goad, L. J., and Goodwin, T. W., Prog. Phytochem., 3, 113–198 (1972).
8.	Nes, W. R., Lipids, 9, 596–612 (1974).
9.	Eardley, A. J., Spec. Stud. Utah geol. mineral. Surv., 5 (1963).
10.	Hoering, T. C., Yb. Carnegie Instn Wash., 303–307 (1969).
11.	Philippi, G. T., Geochim. cosmochim. Acta, 29, 1021–1049 (1965).
12.	Balogh, B., Wilson, D. M., and Burlingame, A. L., Nature, 233, 261–263 (1971).
13.	Maxwell, J. R., Cox, R. E., Ackman, R. G., and Hooper, S. N., in Advances in Organic Geochemistry 1971 (edit. by von Gaertner, H. R., and Wehner, H.), 277–291 (Pergamon, Oxford, 1972).
14.	Bradley, W. H., Bull. geol. Soc. Am., 81, 985–1000 (1970).
15.	Van Horn, A. R., and Djerassi, C., J. Am. chem. Soc., 89, 651–664 (1967).