Eudesmane derivative

Two further sesquiterpene isothiocyanates were isolated from A. cannabina as minor metabolites. The first (243) is based on the epi-eudesmane skeleton while the next (244) is related to alloaromadendrene [252]. A third isothiocyanate (245) which is a ds-eudesmane derivative... 

Ahmed AA, El-Seedi HR, Mahmoud AA, El-Aziz A El-Douski A, Zeid IF, Bohlin L (1998) Eudesmane Derivatives from Laggera crispata and Pluchea carolonesis. Phytochemistry 49 2421... 

A new method of constructing isopropylidene functionality has been illustrated recently in the synthesis of 4(14),7(ll)-selinadiene (202), a eudesmane derivative present in hops.92 Interest continues in the isolation, structural elucidation, and... 

More recently " the naturally occurring cyclopropenones 9 and 11 have been isolated from Telekia speciosa. The terpene derivative with the 7a-H, compound 9, is also found in Lychnophora passerina together with an isomer tentatively assigned as the Ip-H epimer 10 and not the eudesmane derivative 11 as initially thought. 

In an effort to mimic the proposed cyclization of the germaci tdienyl cation (450) to the cadinane skeleton, Ito et a/.215 have examined the fate of the four hedycaryol phenyl sulphides (451)—(454) on reaction with methyl iodide (cf. Vol. 10, p. 51). In all four cases the products derived (455)—(462) were eudesmane derivatives and this finding has been explained in terms of Hi-induced cycliz-ations, the HI being generated from the initially formed sulphonium salts. De-... 

The racemic form of a new sesquiterpenoid, voleneol diacetate (394), has been identified as a constituent of the stem bark of Lepidotrichilia volensii Leroy. Several new eudesmane derivatives have been isolated from various species of Verbesina and their structures, (395)—(398), determined by spectroscopic methods.Related investigations have shown that cuauhtemone (399) (Vol. 5, p. 74) and the eudesmane derivative (400) are metabolites of Pluchea foetida while y-selinen-8-one (401) occurs in the roots of Peteravena schultzii ... 

Nine eudesmane derived sesquiterpenes were isolated from Aristolochia species. Among them, a- and P- eudesmols (325), (326), a-, P- and 8- selmenes (319), (322), (321) and selina-3,7(ll)-diene (320) were found in the essential oils of various Aristolochia members. Govindachari et al. [334] isolated aristolochene (324), a sesquiterpene... 

Well-known eudesmane derivatives in flavors and fragrances include a- and p-selinene from the oils of Cannabis saliva var. indica (Moraceae), celery (Apium graeveolens, Umbelliferae) and hops (Humulus lupulus, Moraceae), (+)-a- and (+)-P-eudesmol from some oils of eucalyptus (Eucalyplus macarlhuri), (-)-epi-y-eudesmol with its woody odor from the north African oil of geranium (Pelargonium odoralissimum and allied species), and the almost odorless diastereomeric (+)-y-eudesmol from various ethereal oils (+)-p-Costus acid and (+)-p-costol belong to the constituents of the essential oil obtained from the roots of Saussurea... 

Cryptomeridiol (227) is a fully saturated eudesmane from heartwood of Cryptomeria japonica (381). From the heartwood of red sandal (Pterocarpus san-talinus) a number of eudesmanes have been isolated, of which pterocarpdiolone (228) may be mentioned (246). Costic acid (229), a eudesmane acid, is present in costus root oil (30). Laevojunenol (230) from vetiver oil (Vetiveriazizanioides) of North Indian origin is an example of e t-eudesmane derivative (345). Of the many presently known eudesmanolides only a few have been isolated from woody parts of plants (+)-dihydro-/8-cyclocostunolide (231) was obtained from trunkwood of Moquinea velutina (146). 

Many plants produce defence secretions that form protective barriers when the structure of the plant is damaged and exposed to air. Examples include pine rosin and rubber. In some cases, the exudates contain antibacterial or antifungal components as is the case, e.g., with myrrh. This is the resin of the shrub Commiphora abyssinica that contains a number of such compounds including the eudesmane derivative (15). 

A. Garcia-Granados, A. Parra, F. Rivas, A.J. Segovia, Seven-membered cyclic sulfite eudesmane derivatives partial synthesis, structural determination, and enzymatic resolution, J. Org. Ghem. 72 (2007) 643-646. 

A fiirther investigation of the trunkwood of the first specimen of E. nitens (Enl) led to the isolation of three authentic eudesmane derivatives, the new emmotinol-A and -B besides the previously known pterocarptriol (24) (Figure 2) and rearranged eudesmane sesquiterpenes, comprising (+)-rishitinol (Table I), a stress compound from Solanaceae (25), and 14 new emmotins represented by 3 tetralones (Table II), 10 naphthalenes (Table III) and 1 naphthoquinone (Table IV) (27). 

The sesquiterpenes (+)-10-epijuneol466, (4.54) and ( )-calameon467) (4.55) have been obtained via addition of 6-isopropyl-3-methyl-2-cyclo-hexenone to cyclobutene derivatives. A similar sequence has been applied for the synthesis of an eudesmane precursor (4.56)468). 

Sesquiterpenoids based on the axane skeleton (354) have been reported previously as metabolites of marine sponges or algae (cf. Vol. 5, p. 77 Vol. 6, p. 89). Further investigations in this area have revealed the presence of axisonitrile-4 (355), axisothiocyanate (356), and axamide-4 (357) in the sponge Axinella cannabina. These compounds are A -derivatives of known metabolites (axisonitrile-1 etc.) of this sponge and are included in this section because their biosynthesis may involve rearrangement of a eudesmane precursor. 

Occidentalol (628), a eudesmane-type sesquiterpene isolated from the wood of Eastern white cedar, was synthesized from a as-fused decalin system (627) prepared by cycloaddition of the a-pyrone (625) with 4-methyl-3-cyclohexenone (626 Scheme 140) (72TL4651). Derivatives of 2-pyrone have also been employed in syntheses of colchicine (629 Scheme 141) (59AG637) and barrelene (630 Scheme 142) (69JA2330). 

The isoxazolidines derived from aldehydes (17a-b) were converted to eudesmane sesquiterpenes. Thus, quatemization of isoxazolidine (18) was followed by ring expansion via a Stevens rearrangement. 

Fig. 38 Examples of molecules prepared following new concepts in total synthesis (a) intricarene (220) generated by protective group-free synthesis and (b) late-stage site-selective C-H oxidations to generate eudesmane-type terpenes like 222 or (c) to prepare the hydroxylated artemisinin derivative 223...

The structure of tetrahydroatractylon monoxide, the compound derived from aerial oxidation of the hydrogenation product of atractylon (460), has been assigned as (461). A full paper on the structure of the bio genetically important sesquiterpenoid rosifoliol (462) has been published. Two bromo-eudesmanes. 

Syntheses of the following eudesmane sesquiterpenoids have been recorded (642),287 (643),287 (644),287 (+)-(3-cyperone (645),288 p-costol (646),289 arctiol (647),289 and vetiselinenol (648).290 The photo-adduct (649), derived from 1,2-bis(trimethylsiloxy)cyclobutene and (—)-piperitone, has been converted into the... 

The biosynthesis of PR toxin (723), derived from Penicillium roqueforti, has been examined by incorporation of [l,2-13C2]acetate into the fungus.325 The labelling pattern as observed from the 13C n.m.r. spectrum is completely in accord with the original Robinson proposal involving a C-10, C-5 methyl migration from a eudesmane-type precursor, as has been demonstrated before. 

One interesting facet of the germacrane-type sesquiterpenoids is the conformation of the ten-membered ring. This aspect has previously been discussed in terms of transannular electronic effects (anomalous u.v. spectra) and transannular chemical reactions (Cope rearrangement and cyclisations to eudesmane and/or guaiane types). Recently, the power of two spectroscopic techniques has been brought to bear on this problem. The first of these is the use of the Nuclear Overhauser Effect (NOE) and the second is the A"-ray analysis of a suitable derivative. 

There are relatively few examples of eudesmane-type sesquiterpenes in which the ring fusion is cis. Hortmann has suggested that these types may be derived by a thermally-allowed disrotatory closure of the hypothetical precursor (267) to give (268) and/or (269). The structure of the naturally-occurring sesquiterpene, occidentalol, has, in fact, been revised by Hortmann and De Roos in favour of (268). Recently, Tomita and Hirose have isolated occidenol (previously called occidiol) from Thuja koraiensis. On the basis of spectral evidence and from the fact that both (—)-occidenol and (—)-elemol (250) gave the same hydroxy-keto-ester (270) on oxidation and esterification (epimerisation at C-5 appears to... 

Biogenetic schemes have been postulated to account for those sesquiterpenes which can be formally related to a eudesmane-type precursor via a 1,2-methyl migration (see Scheme 4). Thus, the skeletal and stereochemical features exhibited by the eremophilane-type (281) sesquiterpenes can be rationalised in terms of a precursor such as the cation (278), derivable from (277). By similar reasoning. 

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