Nor-sesquiterpenoids

In two independent studies three [(468)—(470)] of the four possible dia-stereoisomers have been synthesized and none of these has proved to be identical to the naturally occurring compound. This only leaves (471) as the final possibility with a cycloeudesmol structure. It may, however, be that this compound requires further investigation since the n.m.r. spectrum seems to have some anomalous features [e.g. the isopropylol methyl groups are reported at S 1.25 and 1.33 whereas the lowest-field methyl signal in (468)—(470) is at S 1.11 in addition, the cyclopropyl protons are reported as two doublets, / = 5 Hz, with no apparent coupling to the C-4 proton]. Complete details of the synthesis of the nor-sesquiterpenoid chamaecynone (472) have been published. A new route to... 

Six new compounds (418)—(423) have been isolated from Cacalia species and identified as derivatives of the co-metabolites cacalol (417) and the nor-sesquiterpenoid maturinone (424) cf. Vol. 1, p. 102). Compounds of this type are... 

The triol (130) has been isolated from the micro-organism Fusicoccum amy-gdali, the acid (131) from Cedrus deodara is probably a nor-sesquiterpenoid, the thymoquinol ether (132) is reported to occur in Blumea membrancea, and... 

A component of the defensive secretion of gyrinid beetles has been identified as the nor-sesquiterpenoid aldehyde gyrinidal (21). The odour... 

Jurek, J. and Scheuer, P.J. (1993) Sesquiterpenoids and nor-sesquiterpenoids from the soft coral Lemntdia afncana. I. Nat. Prod., 56, 508-513. 

Izac, R.R., Schneider, P., Swain, M., and Fenical, W. (1982c) New nor-sesquiterpenoids of apparent nardosinane origin from Pacific soft coral Paralemnalia thyrsoides. Tetrahedron Lett, 23, 817-820. 

Figure 12.3 GC/MS (a) and THM GC/MS (b) curves of aged dammar. Peak assignments 2, a cubebene 3, copaene 4, ft bourbonene 8,10 12, cadinane type pyrolysis fragments 14 16, cadinene type pyrolysis fragments 17, calamanene type pyrolysis fragments 18 21, unidentified sesquiterpenoids 22, dammaradienone 23, dammaradienol 24, nor a amyrone 25, 28 nor olean 17 en 3 one 26, dammarenolic acid methyl ester 27, oleanonic acid 28, hydroxydammarenone 29, oleanonic aldehyde 30, ursonic acid methyl ester 31, ursonic aldehyde 32, nor (3 amyrone 34, 20,24 epoxy 25 hydroxy 3,4 seco 4(28) dammaren 3 oic acid methyl ester 35, 20,24 epoxy 25 hydroxy dammaren 3 one 36, dammaradienol...

The nor-ketone rudbeckianone (244) has been identified in Rudbeckia lacini-ata A very interesting new sesquiterpenoid ketone, (+)-bicyclohumulenone (245), has been isolated from the leafy liverwort Plagiochila acanthophylla subsp. japonica The structure and absolute stereochemistry of this compound were ascertained by X-ray crystallographic analysis of the mono-p-bromobenzoate of the derived triol (246). This ketone co-occurs with the two enantiomeric sesquiterpenoids (-)-maalioxide (247) and (+)-cyclocolerenone (248). 

The sesquiterpenoids that are important in odour terms mostly have complex cyclic structures. The problem of elimination of alcohols to produce olefins on attempted isolation is even more acute with sesquiterpenoids than with monoterpenoids because of their higher boiling points, which require more vigorous distillation conditions. The sesquiterpenoids responsible for the odours of vetiver and patchouli oils have complex structures which can only be reached by lengthy and hence uneconomic syntheses. Some of these components are shown in Figure 4.33. The vetivones are the major components of vetiver oil but contribute little to the odour. Minor components such as zizanal and khusimone are much more important. Similarly in patchouli oil, minor components such as nor-patchoulenol and nor-tetrapatchoulol are more important than the major constituent, patchouli alcohol. 

In a later study, the aroma constituents of a Bavarian (Pilsener) beer brewed in Hallertau, near Munich, which possessed a desirable fine hop aroma, was examined [58]. Neither the terpenes and sesquiterpenes nor the methyl esters characterized in hop oil were detected but fraction IV (Table 13.6), which contained terpenoids and sesquiterpenoids, possessed an intensive pleasant hoppy odour. Noteworthy amongst the identified constituents are the cyclic ethers (80)-(86) first found in Japanese hops, the flowery notes of which contribute to hop aroma, and the sesquiterpenoids derived from humulene such as humulene epoxide I, humulene epoxide II, humulol, and humulenol II. Similar results were found with American beers [60, 86]. Humuladienone (79)... 

Vetiver and patchouli are two oils of great importance in perfumery (Williams, 1996, 2004). Both contain complex mixtures of sesquiterpenoids, mostly with complex polycyclic structures (Sell, 2003). The major components of vetiver oil are a-vetivone (136), P-vetivone (137), and khusimol (119), but the most important components as far as odor is concerned are minor constituents snch as khusimone (151), zizanal (152), and methyl zizanoate (153). Nootkatone (154) is an isomer of a-vetivone and is an important odor component of grapefruit. Patchouli alcohol (145) is the major constituent of patchouli oil but, as is the case also with vetiver, minor components are more important for the odor profile. These include nor-patchoulenol (155) and nor-tetrapatchoulol (156) (Figure 526). 

Gorham(72< ) reported that lunularin (595) and lunularic acid (598) were found in the Hepaticae, but not in the Musci and the Anthocerotae. Chemical differentiation between the Hepaticae and the Musci is also observed with respect to terpenoids and lipophilic aromatic compounds. The Hepaticae produce mono-, sesqui- and diterpenoids as well as lipophilic aromatic compounds. By contrast neither mono- and sesquiterpenoids nor lipophilic aromatic compounds have been found in the Musci which have been analyzed so far, except for the presence of one kaurane-type diterpene (508) in Saelania species (272). This characteristic difference in chemical constituents is due to the following fact. Most species of the Hepaticae possess oil bodies which contain the terpenoids and the lipophilic aromatic compounds, whereas, the Musci do not contain oil bodies. Terpenoids and aromatic compounds are major constituents of the Hepaticae and can be used as important chemosystematic markers at different taxonomic levels 13a, 19, 21, 25a, 26—29, 33, 34, 45—47, 67, 69, 74, 334). Although flavonoids are not major components of the Hepaticae, these can also be used as chemical markers (187—198, 200—205, 259, 264, 310—312, 328, 329). Taxonomic use of biochemical data for all hierarchical levels of the bryophytes was reviewed by Suire and Asakawa (310—312). The chemosystematics of the Marchantiales were reviewed by Markham and Porter (199). 

The nitrogenous sesqui- and diterpenes are common in the order Axinellida, but they have also been found among Astrophorida. These are sesquiterpenoids, nor-sesquiter-penes and diterpenes associated with various types of nitrogen-containing molecules, and they may constitute a particular category of meroterpenes. 

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