Alcohols patchouli

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). 

Occasionally, however, things can go awry and examples exist in the chemical literature (albeit very few in number) of natural products whose structures, even after the "structure confirmation" by total synthesis, were shown to be incorrect in the light of the results obtained by X-ray crystallographic analysis. Patchouli alcohol, a natural sesquiterpene of some interest in the perfumery industry, provides an illuminating example. 

Later on, however, X-ray crystallographic analysis by Dunitz of a single crystal of the corresponding chromic diester [11] showed that the actual structure of patchouli alcohol was that of a bridged tricyclic compound (4) (Scheme 1.1), with all its rings having six carbon atoms. 

In fact, a "diabolic confabulation" of two rearrangements, one in the course of degradation of patchouli alcohol to a-patchoulene (4-5) and another one in the... 

As an example of strategic bond selection let us consider the polycyclic network of patchouli alcohol (which is, in fact, a homoisotwistane) and see how a feasible synthetic route to its nor-derivative could acmally be performed. 

TABLE 7.1. Strategic bonds of patchouli alcohol skeleton... 

Strategies based on some special topological features, such as the presence of "strategic bonds" and/or "common atoms" which apply preferentially to sesquiterpene compounds (as, for instance, longifolene, patchouli alcohol, seychellene, sativene, etc.) and non-natural compounds with a high degree of internal connectivity as, for example, twistane, bullvalene, etc. 

Previous work by Holton [15] on the synthesis of taxane ring systems, indicated that the preparation of the bicyclo[5.3.1]undecane skeleton lies basically on the work of Biichi on patchouli alcohol [16], which led him to the development of the so-called "epoxy alcohol fragmentation" [15a]. 

Draw the structures of twistane, tropinone, exo-brevicomin, patchouli alcohol, longifolene, sativene, luciduline and porantherine and search bifunctional relationships, rings, synthetically significant rings, bridgeheads, core bonds and strategic bonds of each one of them. 

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%. 

Sesquiterpenic alcohols used in perfumery are mainly of natural origin. Three alcohols of this type are shown in Figure 8. Cedrol is the main alcohol constituent of cedarwood oil. Alpha-santalol constitutes about 80% of sandalwood oil and about 30% patchouli alcohol is found in patchouli oil, a very popular woody-earthy fragrance material. 

Closely related to Java patchouli (P. heyneonus) known as false patchouli and sometimes used to produce an essential oil. The true oil is a viscous amber colour with a sweet earthy odour. Its main component is patchouli alcohol (up to 40%) with bulnesene (14-17%), seychellene (8.5-9.5%), caryophyllene (3-4%), 3-patchoulene (2.7-4%). There are a variety of attributed therapeutic properties. For the mind it is said to be a grounding oil helpful for those who feel depressed, detached and exhausted. Applied to the circulation it is considered stimulating, as a diuretic and for skin healing in conditions like acne and eczema. It is often used as a fixative in oriental perfumes, and a deodorizer as it masks unpleasant smells. Due to its very strong odour it is advisable to use in low proportions in a blend. Generally considered to be a safe oil as it is non-irritant and non-sensitizing. 

Patchouli alcohol Pogostemon cablin (patchouli oil) (Lamiaceae) OD-R (fragrant)... 

In an examination of the mechanism of the solvolysis of the tricyclic alcohol (627) which led to the successful synthesis of seychellene (628), Frater has shown that the minor product is the tricyclic olefin (629) which is formed by the process depicted in Scheme 79. An alternative synthesis of seychellene (628) and patchouli alcohol (635) depends upon the construction of the key tricyclic ketol (631) by an intramolecular Michael reaction followed by an aldol cyclization of (630) (Scheme 80). The minor ketol (632) can be converted into epi-sey-... 

Thomas and Ozainne have published the full details of the reaction of patchouli alcohol (635) with lead tetra-acetate which produces the bicyclic ketone (637) as a major product. This ketone is the source of a number of interesting rearrangements as outlined in Scheme 82. What is particularly intriguing about... 

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