Triterpenoids aromatic/aromatization

Mobile phase spectra of Blind Canyon coal look rather similar to Beulah-Zap lignite coal with regard to the peaks at m/z 324, 342, 424. Alkylsubstituted naphthalenes components are clearly separated and the other dominant peaks at m/z 310, 324, 342, 356 are believed to originate from triterpenoid aromatization (26). The mass spectra of Blind Canyon coal, which contains 11% resinite, illustrate the importance of depositional environment as well as of rank in determining the components in the mobile phase. 

Fig. 5.22 Examples of triterpenoid aromatization (large arrows indicate biogenic inputs). For A171 21- and A13( 18-) hopenes only D and E rings are shown A, B and C rings are identical to those in diploptene (after Greiner et al. 1976 Tan Heit 1981 Chaffee Johns 1983 Simoneit 1986 Hayatsu et al. 1987).

Fig. 2. Scheme for the alteration of triterpenoid precursors from higher plants to samrated and aromatic derivatives (natural product examples are boxed, stereochemistry is indicated where known). 

Alicyclic, aromatic, aliphatic, steroidal and triterpenoid 1,2-diols are cleaved by iodine triacetate and iodine(I) acetate to generate carbonyl compounds. Aldehydic products are not further oxidized. Iodine triacetate is prepared from iodine trichloride and silver(I) acetate, whereas iodine(I) acetate is prepared from iotUne and silver(I) acetate. Reactions occur in acetic acid at room temperature under nitrogen, and a radical pathway involving a hypoiodite is suggested. The cost and the availability of these reagents are probable reasons for their unpopularity. 

Whereas empirical force-field calculations predict a ring A boat conformation for lanost-8-en-3-one, combined empirical force-field-extended Hiickel molecular orbital calculations favour a ring A chair conformation. Europium-shift n.m.r. results indicate that the molecule adopts the latter conformation. Studies on the peracetic acid-boron trifluoride etherate Baeyer-Villiger oxidation of 4,4-dimethyl-3-keto-triterpenoids to 5-lactones (18) and their subsequent ring contraction to y-lactones have been reported. Dehydrogenation of lanost-8-en-3j8-ol with 2,3-dichloro-5,6-dicyanobenzoquinone afforded, in addition to the corresponding 7,9(1 l)-diene, the aromatic seco-lanostane derivatives (19)... 

The polycyclic aromatic hydrocarbons (PAHs) in brown coal consist predominantly of pentacyclic angularly condensed hydroaromatic moieties. These compounds appear to be derived from C30 triterpenoid... 

Aromatization of ring b of tetra- and penta-cyclic triterpenoids [e.g. 

Structure and Biological Activity of Triterpenoids and Aromatic Compounds from Medicinal Plants... 

This paper presents data on isolation and identification of the following types of geolipids from the Aleksinac oil shale, a Miocene lake sediment n-al-kanes, iso- and/or anteiso-alkanes, aliphatic iso-prenoid alkanes, polycyclic isoprenoid alkanes, aromatic hydrocarbons, saturated unbranched, aliphatic isoprenoid, hopanoic, and aromatic mono- and poly-carboxylic acids, fatty acid methyl esters, aliphatic y- and 6-lactones, cyclic y-lactones, aliphatic methyl- and isoprenoid ketones, and the triterpenoid ketone adiantone. Possible origin of the identified compound classes is discussed, particularly of those which had not been identified previously as geolipids. 

Most of the geolipids so far identified in the oil shale from Aleksinac represent well known and ubiquitous constituents of sediments n-alkanes, iso- and anteiso-alkanes, aliphatic and cyclic isoprenoid alkanes including steranes, triterpanes and tetrater-panes, aromatic hydrocarbons, and aliphatic, hopanoic and aromatic acids. Moreover, several classes of compounds were identified which were also known as constituents of some ancient sediments but were not found to be ubiquitous, such as aliphatic isoprenoid ketones, aliphatic methyl ketones and the triterpenoid ketone adi-antone. 

As for steroids, defunctionalization of pentacyclic triterpenoids occurs during early diagenesis and reduction or aromatization later. Some bacterial degradation of triterpenols has even been observed in the leaves of... 

The greatest abundances of higher plant derived aromatic triterpenoids and their degradation products are, not surprisingly, found in brown coals. However, aromatic hopanoids and related compounds can also be... 

Until now, we have isolated over 50 triterpenoids, about 100 diterpenoids, more than half being new compounds, a total of 15 sesquiterpenoides and sesterterpenoides, 40 flavanoides and several aromatic compounds. Recently we have studied quite a number of Salvia species and isolated various group of compounds. The structures of the new compounds are discussed below. 

This volume continues the series with chapters describing the reports and progress in the total synthesis of aromatic steroids, carbohydrates, genes, pyrrole pigments, and triterpenoids since the appearance of Volumes 1 and 2 some ten years ago. 

Candelilla wax is derived from the leaves of the small Candelilla shrub, which grows in northern Mexico. It is yellowish-brown, hard, brittle, and aromatic. Candelilla wax mainly consists of hydrocarbons (about 50%, chains with 29-33 carbons), as well as esters of high molecular weight (20%-29%), free fatty acids (7%-9%), and resins (12%-14%, mainly triterpenoid esters). It is insoluble in water, but soluble in many organic solvents such as acetone, chloroform, and benzene. Candelilla wax melts in the range 68.5°C-72.5°C. ... 

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