Rearranged sterenes in a shale: occurrence and simulated formation

The lipids extracted from a bituminous shale contained (20R)- and (20S)-5β,14β-dimethyl-18, 19-dinor-8α,9β,10α-cholest-13(17)-enes [(I) and (II); R = H]. Also present were homologues carrying nuclear methyl groups and variously alkylated side chains.Cholestanol has been treated under chemical and mineralogical conditions to yield these backbone-rearranged products. The value of these reactions as simulators of geological diagenesis, and the utility of these sterenes as biological markers in the geological environment is discussed.