A-eudesmol

Quatemization of the resulting tetrahydro-l,3-oxazine (20) and subsequent hydrogenolysis with lithium in liquid ammonia provided the nitrogen-free ( )-5-epi-a-eudesmol. 

The volatiles of fresh leaves, buds, flowers and fruits were isolated by solvent extraction and analysed by capillary gas chromatography-mass spectrometry. Their odour quality was characterized by gas chromatography-olfactometry—mass spectrometry (HRGC-O-MS) and aroma extract dilution analysis (AEDA). In fresh bay leaves, 1,8-cineole was the major component, together with a-terpinyl acetate, sabinene, a-pinene, P-pinene, P-elemene, a-terpineol, linalool and eugenol. Besides 1,8-cineole and the pinenes, the main components in the flowers were a-eudesmol, P-elemene and P-caryophyllene, in the fruits (EJ-P-ocimene and biclyclogermacrene, and... 

Similar strategies were used by Booker-Milburn et al. in approaches toward the synthesis of dictyol C and a-eudesmol [215], and by Blake et al. in approaches toward the synthesis of ophiobolin F and fusicoccin A [216]. 

Conversion of ekmol to eudesmals. Thermolysis of elemol (1) at 210-220 results in partial isomerization to hedycaryol (2). Addition of a trace of silver nitrate to the thermolysis leads to formation, in addition to (2), of a-eudesmol (3) and -cudcsmol (4), both in about 0.8 % yield. This transformation appears to be the first instance of silver(l) ion-catalyzed transformations involving tc-bonds. 

The protic reaction on occasion is a useful method of alkene formation, but is far from general because the cation intermediate tends to undergo rearrangements.Further, even for cases in which elimination to an alkene is the predominant pathway, the regioselectivity of the process is often mediocre. A key step in the synthesis of (+)-a-eudesmol and (-)-a-selinene exemplifies this point (Scheme 60). There are, however, isolated examples of excellent selectivity, such as the reaction of a 3-ketotetrahydrofuran tosyl-hydrazone salt to give the corresponding cyclic enol ether as the major product (Scheme 61), the intro-... 

The protic Bamford-Stevens reaction has been successfully utilized in the asymmetric synthesis of the naturally occurring sesquiterpenes (+)-a-eudesmol and (-)-a-selinene. Here, the more-substituted alkene was formed preferentially (equation 4,1). ... 

This class of compounds may be found in essential oils extracted with both polar solvents and non-polar solvents. The structure of a sesquiterpene alcohol, newly isolated from the oil extracted from the wood of Amyris balsamifera (Rutaceae), has been reported [76]. These investigators either identified by GC-MS or isolated a total of 23 sesquiterpenoids, including valerianol (23) (21.5% of oil), 1-epi-a-eudesmol (24) (10.7%), 10-e/ i -y-eudesmol (25) (9.7%), elemol (26) (9.1%), P-eudesmol (27) (7.9%), y-eudesmol (28) (6.6%), a-eudesmol (29) (4.8%) and P-sesquiphellandrene (30) (4.7%) as the major constituents. 7-... 

Figure 1. Structures of hop oil components. Key I, humulene II, humulene epoxide I III, humulene epoxide II IV, humulol V, humulenol II VI, humula-dienone VII, a-eudesmol VIII, -eudesmol IX, hop ether X, karahana ether XI, p-ionone and XII, j3-damascenone.

New additions to the guaiane family include sclerosporin (609), sclerosporal (610), sclerosporene (611), the guaienes (612) and (613) [which co-occurs with precatabrone (614)], and the guaioxide (615). The unusual pseudoguaiane caespitenone (616) has been isolated from the liverwort Porella caespitans This compound co-occurs with (-i-)-aristolone (617) and (-)-a-eudesmol (618), which are enantiomeric to those found in higher plants. 

The methodology was extended to provide synthetic routes to the sesquiterpenes eudesmane (209), a-selinene (212a), and a-eudesmol (212b) [43,68] (Scheme 6.68). The intermediate diene (208) was found to be a single isomer, presumed to have ( )-geometry. 

The dried stem bark material of Magnolia obovata (Magnoliaceae) is known as Koh-boku. It is an important crude drug in Kampo medicine, used for the treatment of stomach ache and rush of the blood to the head, etc. From this crude drug, magnocurarine, classified as a benzylisoquinoline alkaloid, was isolated [9], in addition to sesquiterpenoids, such as a-eudesmol, and phenylpropanoids, such as magnolol. 

Asakura, K., Matsuo, Y., Oshima, T. et al. 2000. Q-Agatoxin IVA-sensitive Ca channel blocker, a-eudesmol. protects against brain injury after focal ischemia in rats. 394 57-65. 

FIGURE 20.50 Biotransformation of a-eudesmol (153) and (i-eudesmol (157) by Aspergillus niger and Aspergillus cellulosae. 

Only a few volatile sesquiterpenes presenting important central activities are currently known. P-Eudesmol (34) was found to be one of the volatile active principles of the Chinese medicinal herb Atractylodes lancea DC. (Asteraceae) with alleged antagonist properties useful in intoxication by anticholinesterase agents of the organophosphorous type (Chiou et al., 1997). Experimental data show that P-eudesmol (34) prevents convulsions and lethality induced by electroshock but not those induced by PTZ or picrotoxin (Chiou et al., 1995). With a very similar chemical structure, a-eudesmol (35) protects the development of postischemic brain injnry in rats by blocking tS-Aga-IVA-sensitive Ca + channels (Asakura et al., 2000). 

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