Patchoulol

Patchouli alcohol. Patchouli oil comes from Pogostemonpatchouli and the main constituent is patchouli alcohol [5986-55-0] (105) or patchoulol. Another component of the essential oil is norpatchoulenol (106), a norsesquiterpene derivative as a minor (3—5%) constituent, important ia determining the overall odor of the essential oil (197). The price of patchouli oil ia 1995 was 20.90/kg from Indonesia (69). Alarge proportion of the oil (40—60%) is comprised of sesquiterpene hydrocarbons that do not have much odor value. World production of the oil was at about 750 t ia 1984. It is valuable ia perfumery bases because of its characteristic woody, herbaceous odor (198). 

Patchoulol is transformed by Botrytis cinerea to a number of products principally to those involving hydroxylation at the C-5 and C-7 quaternary atoms (Aleu et al. 1999) (Figure 7.45c). 

In practice, such synthetic scheme has been applied [15] to a formal synthesis of nor-patchoulol (37) which proceeds -via radical intermediates [16]- through the hydroxyketone 36 (Scheme 7.12). 

In fact, the reported synthesis of nor-patchoulol 137) (Scheme 7.12) is a good example of how the concept of "strategic bond" is suitable for the synthesis of... 

Patchouli Pogostemon cablin (Blanco) Benth. (-)-Patchoulol (27-35), nor-patchoulenol (0.4-1)... 

One year later, Schalk [89] described a process for cloning sesquiterpene synthases from patchouli plants Pogostemon cablin) and the enzyme-catalysed terpenoid production. Various sesquiterpenes can be obtained by this method, for instance patchoulol and other germacrene-type sesquiterpenes. 

Scheme 23.14 Regioselective biohydroxylation of patchoulol and the following chemical steps to produce norpatchoulenol according to [207]...

N.A. Sesquiterpenes patchoulol, bulnesene.99 Aphrodisiac, antidepressant, antiseptic. 

Patchouli alcohol or patchoulol (203) is a major constituent (30-45%) of the patchouli essential oil which is extensively used in perfumery [68]. The essential oil is obtained by steam distillation of the dried leaves of Pogostemom cablin (Blanco) Benth. (Lamiaceae). Although it is the main component of the patchouli oil, this compound contributes less to the characteristic odour of the oil than nor-pachoulenol (206), present at a concentration of only 0.3-0.4%. 

A process for the production of the latter compound, via the microbial 10-hydroxylation of patchoulol (203) and subsequent oxidation of the 10-hydroxypatchoulol (204) was published [151]. From the 350 microorganisms screened, four strains of Pithomyces species carried out regio-selective hydroxylation of patchoulol to 10-hydroxypatchoulol Pithomyces sp. NRJ201 and P. chartarum NRJ210, isolated from soil situated in the neighbourhood of Kamakura, Japan, the most important ones. A method was developed by which 10-hydroxypatchoulol was obtained in 25 to 45% yields in 1- to 5-litre fermentation jars at 2 to 4 g of patchoulol per litre and isolated as pure material in 30% yields. The... 

Fig. (41). Regioselective 10-hydroxylation of patchoulol by Pithomyces sp. and subsequent chemical conversion to nor-patchoulenol (after [151,152])...

The introduction of hydroxy and carbonyl groups at unactivated positions of terpenoids is usually accomplished by micro-organisms.35 However, recent studies have shown that rabbits can hydroxylate cedrol (72) at a remote unactivated methylene group to provide a mixture of products (73a and b) and (74a and b).36 Patchoulol (298) has also been functionalized in a similar fashion (c/. p. 90). 

A further study on the oxidation of terpenoid compounds by mammalian systems (c/. p. 62) has shown that patchoulol (298) is oxidized by rabbits to give a mixture of diol (299) and hydroxy-acid (300).129 Subsequent oxidative decarboxylation of (300) provided norpatchoulenol (301), the major odour carrier of patchouli oil. It has been suggested that a similar oxidative transformation of patchoulol occurs during the biosynthesis of norpatchoulenol in the plant.129 Cedrol (72) has also been oxidized by rabbits (c/. p. 62) and it is interesting to note that the hydroxylated products are... 

The related tricyclic sesquiterpene patchoulol (48a) is a good substrate for microorganisms and hy-droxylation at various sites can be accomplished, for example at C-S by Choanephora circinana in 74% yield (equation 14). Hydroxylation of the methyl group on C-4 can be accomplished by PenicUlium ru-brum FX-318 in 75% yield,and of the C-14 methyl group in (lf )-caryolan-l-ol (48b) by Aspergillus niger (MMP 521) in 26% yield. ... 

A number of model esters related to lac resin have been prepared. These esters have the basic cedrane skeleton (149) or the C-2 epimeric structure. In an approach to the synthesis of cedrene (152), the intramolecular photocycloaddition of the dienone (150) was carried out at low temperature. A major tricyclic compound (151) was obtained and its structure was verified by X-ray analysis of its anisylidene derivative. Further work is required to bring about the rearrangement of a derivative of (151) to give cedrene. Further details on the hydroxylation (with O3) and chlorination (with PhICl2) of cedrol, patchoulol, and their derivatives have been presented. The results of this study are in keeping with those obtained previously. 

With other fungi various interesting transformation products of patchoulol are found hydroxylation occurs not only at the 10-position, but also at secondary and tertiary carbon atoms. Depending on the fungi employed, these alternate compounds can be the major transformation... 

Treatment of patchoulol (174 Scheme 62), an olfactive component of patchouli oil, with LTA gives rise to a mixture from which the almost pure ketone (175) is distilled. Thomas has postulated a free car-benium ion mechanism, but this reaction may be a legiospecific fragmentation facilitated by the fact that the proton on C(S) is oriented antiperiplanar to the C(l)- bond. 

Further studies on the chemistry of patchoulol (431) have shown that treatment with Pb(OAc)4 provides a 1 2 2 mixture of (432), (433), and (434). The subsequent conversion of (433) into a-bulnesene (436) was also accomplished by... 

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