25th International Meeting on Organic Geochemistry IMOG 2011

P-066
Synthesis of hopanoid hydrocarbons from zeorin and
identification of a new series of rearranged hopanes
Geir Kildahl-Andersen 1 , Hans Peter Nytoft 2 , Jon Eigill Johansen 1
1 Chiron AS, Trondheim, Norway, 2 Geological Survey of Denmark and Greenland, GEUS, Copenhagen,
Denmark (corresponding author:jon.johansen@chiron.no)
Dehydration by perchloric acid treatment of zeorin
(6�-hopane-6,22-diol) provided the two rearranged
hopanoid dienes 1 and 2, identified by way of NMR, in
addition to hopa-5,17(21)-diene (3) and zeorinin (6�hop-17(21)-en-6-ol).
Catalytic hydrogenation of a
mixture of 2 and 3 in presence of perchloric and
acetic acid, gave several new products. In addition to
the partly hydrogenated hopene 4, three saturated
hopanoid products were isolated. Proton and carbon-
13 chemical shifts of compounds 5 and 6 were fully
assigned, whereas the third saturated compound was
isolated in too small quantities for complete structural
assignment. Compounds 4 and 6 are both structurally
related to and therefore also probably formed from
diene 2, while 5 is likely to be formed from diene 3
during hydrogenation. Compound 5 has a similar
structure as 17�(H)-hopane (��30), except for an
unusual 5�(H) configuration.
NMR data of 6 suggested a main conformer in which
the A and B rings, and possibly also the C and D
rings, have reversed conformations compared to
regular hopanes. Moreover, a characteristic fragment
in the mass spectrum at m/z 327 was present, Fig. 1,
formed by fragmentation of the A ring. A homologous
series of compounds (containing 27, 29, 30, 31, 32
and 33 carbon atoms, respectively) with similar
fragmentation patterns was identified in small
quantities in sample oils with high contents of
rearranged hopanes. By way of GC-MS-MS, the C30
homolog was shown to have identical retention time,
mass spectrum, and daughter ion spectrum as the
rearranged synthetic compound 6.
Fig. 1. Mass spectrum of compound 6 obtained from
GC-MS analysis.
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