E. Lichtfouse et P. Albrecht, SYNTHESIS OF TRIAROMATIC STEROID HYDROCARBONS METHYLATED AT POSITION-2, POSITION-3 OR POSITION-6 - MOLECULAR FOSSILS OF YET UNKNOWN BIOLOGICAL ORIGIN, Tetrahedron, 50(6), 1994, pp. 1731-1744
C-21-29 triaromatic steroid hydrocarbons bearing a methyl group at unu
sual positions 2, 3 or 6 have been synthesized from pregnenolone, chol
esterol or stigmasterol via stera-3,5-dienes. Their occurrence in vari
ous sedimentary rocks and petroleums suggests the presence of yet unkn
own biological precursors.