We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Identification of a Fossil Sterane Biomarker in Crude Oil - an Androstane with a Modified Carbon Skeleton.
- Authors
Bender, Matthias; Schmidtmann, Marc; Rullkötter, Jürgen; Summons, Roger E.; Christoffers, Jens
- Abstract
Three constitutional isomers of androstane were prepared for comparison with three unknown fossil C19H32 organic biomarkers ('19A', '19B', and '19C' in elution order) in geological samples from Oman. 3β-Methyl-A- nor-androstane was prepared in six steps (8 % overall yield) from testosterone. The key steps of this sequence were an Eschenmoser fragmentation and recyclization of the A ring. A mixture of four stereoisomers of 3-methyl-A- nor-androstane (4 % overall yield) was prepared by ionic hydrogenation of the olefin after A-ring recyclization in three steps. 17-Methyl-18- nor-androstane was synthesized in four steps as a mixture of isomers (58 % overall yield) from dihydrotestosterone with a Wagner-Meerwein shift of the 13β-methyl group to C-17 as the key step. Pure 17β- and 17α-methyl-18- nor-13α-androstane (4 and 2 % overall yield, respectively) were obtained in three additional steps after α-oxidation of the Wagner-Meerwein rearrangement product and subsequent reduction. The synthesis of 18- nor-D- homo-13β-androstane (12 % yield over seven steps from dihydrotestosterone) involved oxidative cleavage of the C-C double bond in the Wagner-Meerwein rearrangement product from the previous synthesis and subsequent recyclization of the D ring followed by reduction. The relative configurations of all final products were confirmed by X-ray crystallography. A comparison of the synthetic standards with the saturated hydrocarbon fraction of an Oman crude oil by gas chromatography (GC-MS) coinjection on three different GC columns and comparison of mass spectra revealed that unknown compound 19C is 18- nor-D- homo-13β,14α-androstane, whereas the isomeric 3-methyl-A- nor-androstanes and 17-methyl-18- nor-androstanes elute close to 19A and 19B, respectively, but do not match the unknowns.
- Subjects
STERANES; BIOMARKERS; PETROLEUM microbiology; ANDROSTANE; STANOLONE; ISOMERS
- Publication
European Journal of Organic Chemistry, 2013, Vol 2013, Issue 26, p5934
- ISSN
1434-193X
- Publication type
Article
- DOI
10.1002/ejoc.201300788