Hopanes structure

Tetracyclic terpanes such as 17,21- and 8,14-5eco-hopanes (Structures V-VI). 

Tetracyclic terpanes - Tetracyclanes are derivatives of the hopanes. Both 17,21- and 8.14- seco-hopanes are found in fossil fuels. The 17,21-seco-hopanes have ring-E opened hopane structure, and the 8.14- seco-hopanes have ring-C opened hopane structures - The tetracyclic terpanes found in the SWMs are comprised of a C24-17,21-seco-hopane (in other words -norhopane) and C28 and C29-8,14-seco-hopanes - The total concentrations for the SWMs ranged from 1.0-1.7 mg/g OC and 0.07-0.33 pg/g OC for their leachates, respectively - Petroleum and petrochemical products 1,71-73... 

Kajukova GI, Pustulnikova GD, AbruitinaNN, Golovkina LS, MeshtuevaVL, Petrov AA, Structural variations in hopane type hydrocarbons, Neftechimiya 21 803-811, 1981. 

Advances in petroleum characterization at the molecular structure level by GC-MS methods renewed interest in OSC. Within the past few years, at least one-thousand new and novel OSC that previously were not known to be present in petroleum and bitumens have been reported. Tentative molecular structures inferred from GC-MS and other techniques have been confirmed in many cases by synthesis of authentic reference-compounds. The difficult and time-consuming synthetic work has been crucial in validating many of the novel structures. Another key finding has been that immature bitumens and crude oils (samples that have not received significant thermal stress) differ markedly from the previously known OSC in that they have carbon-skeletons resembling ubiquitous biomarker hydrocarbons (e.g., n-alkanes, isoprenoid alkanes, steranes, and hopanes). This similarity, of course, suggests that the hydrocarbons and OSC have common biogenic precursors. 

Figure 9.10 The general chemical structure of hopane and the simplest C30 hopanoid, diploptene.

Lead tetra-acetate-iodine oxidation of hopan-7a-ol, hopan-15/3-ol, and the corresponding 21 aH epimers resulted in functionalization of the 80, 14a, and 18a methyl groups.129 The details of the chemical investigation of spergulagenin A (169), from Mollugo spergula, whose structure was established by X-ray analysis, have been published.130... 

The pentacyclic component at m/e 412 resembles the spectrum of oleanane (structure shown) or gammacerane. It is also similar to that of lupane (13, 15) but lacks the M-43 (369) fragment indicative of any isopropyl sidechain. Therefore, ring E is probably 6-member-ed, not 5-membered as in lupane or the hopanes. Although the mass spectrum is a slightly better match to gammacerane, the short GC retention time probably rules out gammacerane but not oleanane (13). 

In 1973 the structure (157) or (158) was proposed for a C35 hopane derivative, bacteriohopanetetrol, from the bacterium Acetobacter xylinum. Structure (157) is attractive as a precursor for the extended hopane derivatives obtained from geological sources (see Vol. 3, p. 228 and Vol. 5, p. 145). Rohmer and Ourisson have now confirmed"" the validity of (157) and have shown the presence of both (22R)- and (225)-epimers. Periodate cleavage of the tetrol followed by sodium borohydride reduction and acetylation afforded the epimeric acetates (159) identical with synthetic samples prepared from diploptene (160). A range of Acetobacter species and... 

The aromatic derivatives (165) and (166) have been isolated from several geological sources." They probably arise by progressive geochemical aromatization of hopane precursors. The structures were confirmed by synthesis. 

Two new rearranged hopanes, alangidiol (178) and isoalangidiol (179), with a d-e cis fusion have been reported from the leaves of Alangium lamarckii. New fernene derivatives which have appeared this year include fern-9(l l)-en-6a-ol (180) and fern-9(ll)-en-20j8-ol (181) from the rhizomes of Polypodium juglandifolium and hortensol (182) from the leaves of Evodia hortensis The structure of (182) was confirmed by A"-ray analysis. 

Two naturally occurring ozonides, gilvanol (213) from Quercus gilva and adian-5-ene ozonide (214) from the leaves of Adiantum monochlamys, °° have been isolated. Their structures were readily confirmed by the action of ozone on hop-17(2l)-en-3jS-ol and adian-5-ene respectively. Amphistictinic acid (215), from the lichen Pseudocyphellaria amphisticta, is 15a-acetoxy-22-hydroxy-hopan-24-oic acid. The structure of the 6a,7a,22-trior previously reported from the lichen P. mougeotiana has been revised to 6a,7/3,22-tri-hydroxyhopane (216). The Tlj8,22-dior isolated from the same source has been shown to be a mixture of 7/8,22- (217) and 15a,22-dihydroxyhopane (218). 

The main kind of anti-inflammatory triterpenes isolated have oleanane, ursane, taraxastane, lupane and lanostane skeletons (Table 1). Some minor compounds such as hopane are included in other structural groups. Other anti-inflammatory triterpenes like the different cucurbitacins are not included in this review because of their high toxicity. 

The phenanthrene and chrysene structures could be derived from cyclic terpenoids such as abietic acid, sterols, and hopanes (34). Although tri-phenylene, which has the highest resonance energy among the four-ring catacondensed PAHs (35), was not present in the SRC II HD at a significant level, this compound was found in the coal tar which is a higher temperature... 

Saturated alicyclic hydrocarbons Typical compound hopane C30H52 structure ... 

Two new hopanes, methyl pyxinate (172) and the corresponding acetate (173), occurin the lichen Pyxine endochrysina along with several dammaranes. Full papers have appeared on the structure of leucotylic acid (174) and on the correlation of zeorin (175) with leucotylin (176). On treatment with acid, methyl leucotylate (177) and leucotylin (176) afford methyl isoleucotylate (178) and isoleucotylin (179), respectively. 

Hopane and homohopane (180) have been identified in Messel oil shale. The structure of homohopane was confirmed by a partial synthesis from diplop-tene [hop-20(29)-ene]. It is suggested that homohopane arises by microbiological methylation and that a significant proportion of the triterpanes found in sediments and oils are of bacterial origin. Tetrahymanol (181) has been isolated from Green River Shale. 

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