0-Damascenone 3-Damascone

Figure 3. Damascenones, damascone, and ionone found in nature as flavorants and perfumes.

Of all these, probably P-phenethyl alcohol (2) comes closest to the odor of fresh rose petals however, mixing all these components does not reproduce the total fine character of the natural oil. It has been determined that a number of trace constituents representing less than 1% of the volatiles are critical to the development of the complete rose fragrance (10). These include cis- and trans-i.ose oxide (1), nerol oxide (12), rose furan (13), /)i7n7-menth-l-en-9-al (14), P-ionone (15), P-damascone (16), and P-damascenone (3). 

Table 20.1 shows the detection thresholds of a number of perfume materials in air and in water. Note the tremendous range (from 0.002 parts per billion for beta-damascenone to 10,000 parts per billion for phenylacetic acid—both taken in water solutions), the large difference between optical isomers of the same substance (e.g., Nootkatone and alpha-damascone), and the large differences in thresholds reported by different investigators (e.g., benzaldehyde and vanillin). In substances with relatively high water solubility such as vanillin and ethyl vanillin, benzaldehyde, phenylethyl alcohol, and phenylacetic acid, the thresholds in water are very much higher than in air. In poorly water-soluble substances such as pinene and the macrocyclic musk cyclopentadecanolid, the reverse is true. The relative thresholds of a substance in different solvents indicate its performance in different application environments. Substances whose thresholds in water solution are much... 

Rose (Morocco) Rose (Bulgaria, Turkey) Rosa centiofolia Rosa damascena (S)-Citronellol, geraniol, nerol (23), 2-phenylethanol, (4R)-rose oxide (24), /3-damascone (25), /3-damascenone (26) 95,96... 

The damascones are a group of materials related to the ionones, but in which the enone unit is transposed. They are components of rose oils and have very intense fruity-floral odours. The damascenones, which contain a second double bond in the ring, are also very much sought after. One synthesis of a-damascone from methyl a-cyclogeranate is shown in Scheme 4.40. A double Grignard addition gives the tertiary alcohol. Heating of this in the presence of base, to prevent elimination... 

Figure 4.2. Principal norisoprenoid compounds in grape and wine. (29) TDN (1,1,6-trimethyl-l,2-dihydronaphthalene) (30) P-damascone (31) P-damascenone (32) vom-ifoliol (33) dihydrovomifoliol (34) 3-hydroxy-P-damascone (35) 3-oxo-a-ionol (36) 3-hydroxy-7,8-dihydro-P-ionol (37) oc-ionol (38) P-ionol (39) a-ionone (40) P-ionone (41) actinidols (42) vitispiranes (spiro [4.5]-2,10,10-trimethyl-6-methylene-l-oxa-7-decene) (43) Riesling acetal (2,2,6-tetramethyl-7,ll-dioxatricyclo[6.2.1.01,6] undec-4-ene).

Diels-Alder catalyst (4, 10-11). Details for the synthesis of j3-damascone and 3-damascenone by the Diels-Alder reaction are now available. ... 

Demole, E. and D. Berthet Identification de la dama-scenone et de la P-damascone dans le tabac burley [Identification of damascenone and P-damascone in bur-ley tobacco] Helv. Chim. Acta 54 (1971) 681-682. 

Megastigmanes (Figure 7.4) are oxygenated Ci3-norisoprenoids, with skeletons oxygenated on carbon 7 (damascone series) or carbon 9 (ionone series). Among these compounds, j6-damascenone, with a complex smell of flowers, tropical fruit and stewed apple, has a very low olfactory perception threshold in water (3-4 ng/1) and a relatively... 

The synthetic chemistry of damascones and damascenones has been reviewed. New syntheses have been reported of /8-damascenone (141) from dimedone, of 3-hydroxy-/3-damascone (142) and 3-hydroxydihydro-/3-damas-cone (143),and of various damascones and their demethyl analogues. ... 

Norisoprenoids detected in negligible amounts or not found in the free fraction of studied wines, were relatively abundant in the bound fraction. The Qs-norisoprenoid pattern was composed by 3-hydroxy-P-damascone, 3-oxo-a-ionol, 3-hydroxy-7,8-dihydro-(3-ionol and, in smaller concentrations, a-ionone and 4-oxo-isophorone. By contrast, (3-damascenone -detected in the free fraction in wines- was not detected in bound form as this compwimd is formed principally from the precursors 3-hydroxy-P-damascone and 3-hydroxy-7,8-dehydro-P-ionol the highest concentration of both compounds found in fraction of aroma of Rojal wines could be related to that in the free fraction Rojal wines paosented lower concentration of P-damascenone. 

One of the most important discoveries recently made in the field of carotenoid aroma compounds relates to the class of damascones. Seven naturally occurring members (266) to (272) of this class are known today. The discovery of these new compounds started with the isolation of damascenone (268) from Bulgarian rose oil in 1970 120). Later, the same compound was detected in various tobacco brands 5, 110, 306), tea 491), raspberry oil 708), cooked apples 442), various grape and wine varieties 546, 549), beer 598), coffee oil 179), buchu leaf oil 283) and Roman camomile 638). 3-Hydroxy-(3-damascone (269) was shown to be an important aroma component of tobacco 108, 169, 285) in which it develops a green, rose-floral and sweet Burley-like note (556). (3-Damascone (267) was found in Burley tobacco 110) and rose oil 108), whereas a-damascone (266), accompanied by (3-compound (267) and damascenone (268), was exclusively observed in tea oil 491). Among the known cyclization products (270) to (272), the last two compounds were found in tobacco (779), while ketone (270) was detected in tea 491). 

IsOE, S., S. Katsumura, and T. Sakan The Synthesis of Damascenone and p-Damascone and the Possible Mechanism of Their Formation from Carotenoids. Helv. Chim. Acta 56, 1514 (1973). 

Besides the Grasshopper ketone, another enin-diol (Formula 3.141) was identified in grape juices. When heated (pH 3), this enindiol yields 3-hydroxy- P-damascone as main and P-damascenone as minor product. 

Damascones The first member of this family to be identified was p-damascenone (343). It was isolated from the Damask rose, Rosa damascena, the oil of which contains 0.05% of it (418) and the structure was confirmed by synthesis (419). Since then, damascones... 

Damascone (356) is not found in nature. It is also known as Dihydrofloriffone. It is very diffusive with a threshold similar to that of damascenone and has a fruity, blackcurrant, floral, and woody odor character. 

P-Damascenone (343) is present in Bulgarian rose oil at a level of only 0.05%, but is a major contributor to the overall odor of the oil. Not surprisingly, it is used in reconstitutions of rose oil. It is also found in rose, apricot, beer, grape, mango, tomato, wine, rum, raspberries, passionfruit, and blackberries. Its detection threshold is one-tenth those of a- or p-damascone. 

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