Use of cycloaliphatic ketones as perfuming and flavoring ingredients

Optically active isomers of alpha-damascone of formula ##STR1## wherein the wavy line designates a C--C bond of cis or trans configuration and its 3-buten-1-one derivative are new compounds having utility in the perfume and flavor industry. They can be prepared starting from an enolate of formula ##STR2## where the wavy line has the meaning given above and Me designates an alkali metal, preferably lithium or magnesium, by treating said enolate with a bifunctional nitrogen derivative of formula ##STR3## where the asterisk identifies a center of chirality; PA0 index n stands for zero or 1; PA0 each of symbols R.sup.0 and R.sup.1 defines a linear or branched alkyl or aralkyl radical, or one of them represents a hydrogen atom and the other an alkyl radical as defined above; PA0 each of symbols R.sup.2 and R.sup.3 represents a linear or branched alkyl radical, or one of them represents a hydrogen atom and the other an alkyl such as defined above; and PA0 Z designates an OH group or a divalent radical of formula HN-C(O), the nitrogen atom of which is bound to the carbon atom at position 3 and the carbonyl group is bound to the nitrogen atom at position 1; PA0 and wherein the nitrogen atom at position 1 can be optionally bound to a benzylic group of a polystyrenic resin; hydrolyzing the reaction mixture and isomerizing it by means of an isomerization agent. Cycloaliphatic ketones (I) are also prepared starting from an organo-magnesium compound of formula ##STR4## where the wavy line has the above given meaning and X designates a halogen atom, by treating said compound with one equivalent of a lithium alkoxide.

BRIEF SUMMARY OF THE INVENTION 
The present invention relates to 
(-)-(1S)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one and 
(-)-(1S)-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-3-buten-1-one. This 
invention relates also to the utilization of 
(-)-(1S)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one as a 
perfuming and flavoring ingredient in the preparation of perfume, perfume 
bases, perfumed products and in the aromatization of edible material. 
The present invention provides further a process for the preparation of 
(-)-(1S)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one of 
formula 
##STR5## 
wherein the wavy line designates a C--C bond of cis or trans 
configuration, which process comprises the steps of 
a. treating an enolate of formula 
##STR6## 
where the wavy line has the meaning given above and Me designates an 
alkali metal, preferably lithium or magnesium, with a proton donating 
chiral reagent consisting of a bifunctional nitrogen derivative of formula 
##STR7## 
where the asterisk identifies a center of chirality; 
index n stands for zero of 1; 
each of symbols R.degree. and R.sup.1 defines a linear or branched alkyl or 
aralkyl radical, or one of them represents a hydrogen atom and the other 
an alkyl radical as defined above; 
each of symbols R.sup.2 and R.sup.3 represents a linear or branched alkyl 
radical, or one of them represents a hydrogen atom and the other an alkyl 
such as defined above; and 
Z designates an OH group or a divalent radical of formula HN-C(O), the 
nitrogen atom of which is bound to the carbon atom at position 3 and the 
carbonyl group is bound to the nitrogen atom at position 1; 
and wherein the nitrogen atom at position 1 can be optionally bound to a 
benzylic group of a polystyrenic resin; 
b. hydrolyzing the reaction mixture to give 
(-)-(1S)-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-3-buten-1-one, and 
c. isomerizing it by means of an isomerization agent. 
This invention provides further a process for the preparation of 
(-)-(1S)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one, which 
process comprises the following subsequent steps: 
a. treating an organo-magnesium compound of formula 
##STR8## 
where the wavy line designates a C--C bond of cis or trans configuration 
and X designates a halogen atom, with one equivalent at least of a lithium 
alkoxide; 
b. adding to the reaction mixture one equivalent at least of a proton 
donating chiral reagent consisting of a bifunctional nitrogen derivative 
of formula (III) as defined above; 
c. hydrolyzing the reaction mixture and isomerizing it by means of a 
current isomerizing agent; or 
a'. treating an organo-magnesium compound of formula (IV) with one 
equivalent at least of a lithium alkoxide consisting of a lithium salt of 
a hydroxylic nitrogen compound of formula (III) as defined above; 
b'. adding to the reaction mixture one equivalent at least of a proton 
donor consisting of an aliphatic alcohol, preferably tert-butanol; and 
c'. hydrolyzing and isomerizing as indicated under letter c. above. 
BACKGROUND OF THE INVENTION 
The present invention relates to perfumery and to the flavor industry. It 
relates more particularly to optically active isomers of alpha-damascone, 
namely the enantiomer of formula 
##STR9## 
or (-)-(1S)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one and 
its -3-buten-1-one derivative. 
Ever since their discovery [see Swiss Patents Nos. 509,399 and 524,320; 
Helv. Chim. Acta, 53, 541 (1970)], the interest encountered by damascones 
and their derivatives has been steadily growing among perfumers and 
flavorists. Their organoleptic qualities make them the ingredients of 
choice in a great variety of compositions destined to a wide range of 
applications. Their use streches from fine fragrances to the perfuming of 
household materials or toiletries such as soaps and detergents. 
In particular, alpha-damascone has found a large utilization in fruity and 
floral type composition and its fragrance character of green apple type 
has enabled the creation of highly appreciated original olfactive notes. 
Numerous publications have appeared reporting processes for its 
preparation. In most of the cases examined, however, these processes 
revert to the preparation of the racemic compound. alpha-Damascone in 
effect has been used so far in its racemic form. 
G. Ohloff and G. Uhde [Helv. Chim. Acta, 53, 531 (1970)] have however 
described a process for the preparation of (R)-(+)-alpha-damascone, or 
(+)-(1'R,E)- and 
(+)-(1'R,Z)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one of 
formula 
##STR10## 
The process is characterized by an oxidation with manganese dioxide of the 
corresponding secondary alcohol which was obtained from (+)-alpha-ionone 
according to the following reaction scheme: 
##STR11## 
The compound thus obtained showed an [alpha].sup.20.sub.D =+324.degree. for 
the E form and [alpha].sup.20.sub.D =+340.degree. for isomer Z. 
M. Shibasaki et al. [Chem. Pharm, Bull., 23, 279 (1975)] have also 
described a process for the synthesis of the same isomer of 
alpha-damascone, which process comprises the diastereomeric cyclization of 
citral by means of a chiral auxiliary reagent via the formation of its 
enamines, as indicated hereinbelow: 
##STR12## 
By making reference to the values given by Ohloff and Uhde, the compound 
thus obtained by the cited authors possessed an optical purity of 27.5% 
and showed and [alpha].sup.20.sub.D =+89.2.degree.. 
We could establish that isomer (R)-(+) thus prepared, while possessing an 
olfactive note characterized by a pleasant fruity and floral note, showed 
also a nuance which was reminiscent of "cork". This rendered its 
utilization somehow problematic. 
This observation led us to examine the nature of the odor properties of the 
other enantiomer, (S)-(-)-alpha-damascone. Unfortunately, in the present 
state of our knowledge, we were not in the position to synthesize such an 
enantiomer lacking an appropriate synthetic method. 
The present invention obviates this problem. 
THE INVENTION 
Suitable proton donating chiral reagents include preferably a hydroxy-amine 
of formula 
##STR13## 
Examples of hydroxy-amines (IIIa) are 
(1R,2S)-2-(methylamino)-1-phenylpropan-1-ol, or 1-ephedrine, 
(1R,2S)-2-(dimethylamino)-1-phenylpropan-1-ol, 
(1R,2S)-2-(isopropylamino)-1-phenylpropan-1-ol, 
(1R,2S)-2-(N-methyl-N-isopropyl-amino)-1-phenylpropan-1-ol, or a cyclic 
derivative of urea of formula 
##STR14## 
for instance the compounds wherein R.sup.1 =CH.sub.3 or isopropyl. 
The first class of reagents mentioned above belongs to the category of 
ephedrine derivatives compounds can be obtained either from ephedrine 
itself or from mandelic acid, both of which are readily available raw 
materials. 
The reagents of the second type belong to the class of cyclic urea 
derivatives known in the art. 
Thus, 1-2-(N-methyl-N-isopropylamino)-1-phenyl-propan-1-ol can be obtained 
from 1-ephedrine by condensation with acetone in ethanol, followed by 
reduction with NaBH.sub.4, whereas 
1-2-(isopropylamino)-1-phenylpropan-1-ol is obtained by an analogous way 
from 1-norephedrine according to J. E. Saavedra [J. Org. Chem., 50, 2271 
(1985)]. 
The other proton donating chiral reagents having analogous structure can be 
prepared according to similar synthetic methods. 
To this class of chiral derivatives belong also the polymeric derivatives 
of known composition and described for instance by J. M. J. Frechet et 
al., [J. Org. Chem., 51, 3462 (1986)]. They are polymeric resins wherein 
the nitrogen atom at position 1 of compounds (III) is bound to the 
p-methylene group of the aromatic radical of the resin. 
Typically, these compounds include the derivatives of formula 
##STR15## 
These reagents possess the considerable advantage of having the faculty of 
being easily regenerated by filtration. 
With regard to the other class of reagents, viz. the cyclic urea 
derivatives, they can also be obtained by known processes. Thus, 
(+)-(4S,5R)-1,5-dimethyl-4-phenyl-2-imidazolidone can be obtained from 
(+)-ephedrine hydrochloride by reaction with urea ([alpha].sup.20.sub.D 
=+44.5.degree. (c=3; CH.sub.3 OH)) according to H. Roder et al., Angew. 
Chem., 96, 895 (1984). 
The hydrolysis of the obtained reaction mixture can be effected by means of 
an acidic aqueous solution, for example by means of a diluted protic acid 
such as hydrochloric or sulfuric acid in water or by treatment with an 
aqueous solution of ammonium chloride, preferably at a temperature lower 
than the room temperature. 
The final step of the process which consists in the isomerization of the 
terminal double bond of the compound obtained by hydrolysis is carried out 
according to known analogous methods, for example by treating the said 
compound with an acidic isomerization agent according to the method 
described for the racemic compound in Swiss Patent No. 537,352 or by 
treatment with alumina. 
The enolate of formula (II) which is used as starting material in the above 
described process can be readily obtained by treating an ester of 
cyclogeranic acid of formula 
##STR16## 
where symbol R designates a linear lower alkyl radical, preferably methyl 
or ethyl, by means of a strong base such as an alkyl- or a phenyl-lithium. 
To this effect, n-butyl-lithium is preferred. 
The present invention provides also an original process for the preparation 
of (S)-(-)-alpha-damascone of formula (I), which process can be 
exemplified by the following reaction scheme: 
##STR17## 
The process consists in three steps carried out subsequently: 
a. treatment of an organo-magnesium compound (IV) with at least one 
equivalent of a lithium alkoxide; 
b. addition to the reaction mixture of at least one equivalent of a proton 
donating chiral reagent consisting of a bifunctional nitrogen derivative 
of formula (III) as defined above; 
c. hydrolysis of the reaction mixture and its isomerization by means of a 
current isomerizing agent. 
Suitable lithium alkoxides include a lithium salt of a lower aliphatic 
alcohol such as methanol, ethanol, isopropanol or butanol, preferably 
tert-butanol. Lithium salts derived from chiral anions can also be used to 
this effect. In this case, lithium derivatives of hydroxy nitrogen 
compounds of formula (III), wherein Z stands for an OH radical, can be 
used. Typically, lithium 
(1R,2S)-2-(N-methyl-N-isopropylamino)-1-phenylpropoxide is employed with 
success. 
Examples of proton donating chiral reagents include bifunctional nitrogen 
derivatives of formula (III) such as defined above. 
By carrying out the first step of the process by means of a lithium salt of 
a chiral anion, the following step can be effected by employing an achiral 
proton donor, e.g. an aliphatic alcohol such as tert-butanol. Therefore, 
according to a variant of the above described process (S)-(-)-alpha 
damascone is obtained by: 
a'. treating an organo-magnesium compound of formula (IV) with at least one 
equivalent of a lithium alkoxide consisting of a lithium salt of a hydroxy 
nitrogen compound of formula (III), wherein Z stands for an OH radical; 
and 
b'. adding to the reaction mixture at least one equivalent of a proton 
donor chosen among aliphatic alcohols, in particular tert-butanol. 
The subsequent steps of hydrolysis and isomerization will be carried out as 
described under letter c. above. 
Organo-magnesium compounds of formula (IV) which are used as starting 
materials in the above described process can be obtained from the 
corresponding ketene, or 2,6,6-trimethyl-cyclohex-2-enylketene, which 
compound can be synthesized in accordance with known methods [see J. Org. 
Chem., 42, 2111 (1977)]. 
Without being limited by hypothesis on the specific reaction mechanism 
which governs the invention processes, on the base of the observations 
accumulated in the course of the different runs carried out in the process 
development, we have come to the conclusion that the formation of a 1:1 
lithium-magnesium mixed complex between the organo-magnesium compound and 
lithium alkoxide represents a critical step for obtaining a high degree of 
enantioselectivity. 
We have discovered surprisingly that the odor properties of the 
(S)-(-)-enantiomer of alpha-damascone prepared in accordance with the 
processes of the invention differ from those of the known racemic 
derivative. (S)-(-)-alpha-Damascone is characterized by a more pronounced 
and fresher floral note. Its odor character was reminiscent of rose 
petals. (S)-(-)-alpha-Damascone possessed moreover a green and slightly 
winey notes without presenting the "cork" tone and the typical green apple 
note of the racemic mixture or of the (R)-(+)-enantiomer. By comparison 
with this latter compound, (S)-(-)-alpha-damascone showed not only marked 
differences from the qualitative point of view but also it distinguishes 
itself by an enhanced odor strength and intensity. An evaluation of the 
respective odor threshold has shown that (S)-(-)-alpha-damascone, with an 
odor threshold value of 1.5 ppb (parts per billion), is roughly 65 times 
stronger than (R)-(-)-alpha-damascone having an odor threshold value of 
100 ppb. Of course, this fact leads in practice to an increased economy 
for the consumer; the new compound of the invention can in effect achieve 
a far superior odor and flavor power than that observed by the utilization 
of equivalent amounts of the known (R)-(+) enantiomer or racemic mixture. 
As a perfuming ingredient, (S)-(-)-alpha-damascone can be used to perfume 
consumable products as varied as soaps, liquid or solid detergents, fabric 
softeners or household materials. It can further be employed for the 
preparation of fragrance compositions destined to fine perfumery. Its use 
can occur either as an ingredient in its pure concentrated form or, more 
often, in admixture with other current perfumery coingredients, carriers, 
excipients or diluents. The man skilled in the art knows by experience 
that the nature of the coingredients in a given composition depends on the 
specific odor effect it is desired to achieve. Suitable coingredients can 
be found in numerous literature sources and they include compounds of 
natural and synthetic origin. 
Concentrations of active (S)-(-)-alpha-damascone can vary in a wide range 
of values in accordance with the type of application, the nature of the 
coingredients and that of the consumable material it is desired to 
perfume. When (S)-(-)-alpha-damascone is used to perfume products such as 
soaps or detergents, for example, concentrations of the order of 0.1-0.5% 
by weight based on the total weight of the product it is desired to 
perfume might be sufficient to confer the desired odor. Concentrations of 
up to 5% or even higher can be used to prepare perfume compositions or 
perfume bases. 
When used as a flavoring ingredient, (S)-(-)-alpha-damascone develops a 
floral note. Moreover, it is reminiscent of tea, especially with regard to 
its herbal character. (R)-(+)-alpha-damascone possesses instead a woody, 
camphory, dirty and musty taste. 
It is interesting to note that (RS)-alpha-damascone develops a fruity 
aromatic note more pronounced than that of the (S)-(-) enantiomer. Owing 
to its organoleptic characteristics, (S)-(-)-alpha-damascone is 
particularly suitable to confer, modify or improve the aromatic properties 
of foodstuffs and beverages of various nature. It can be used to aromatize 
infusion or decoction products, bakery products or pastries, jams or even 
tobacco. The active proportions of (S)-(-)-alpha-damascone in a given 
flavored material can also vary widely. Depending on the desired effect, 
one skilled in the art can make an assessment of the most effective 
values. (S)-(-)-alpha-damascone can be used in admixture with current 
flavoring ingredients. Suitable ingredients are exemplified in the 
technical literature [see e.g. S. Arctander, Perfume and Flavor Chemicals, 
Montclair, N.J. (1969); Fenaroli's Handbook of Flavor Ingredients, 2nd 
Edition, CRC Press, Inc., (1975)]. The aromatization is usually effected 
by employing (S)-(-)-alpha-damascone in solution in edible solvents or on 
supports or carriers. To this effect, ethanol, triacetine, dipropylene 
glycol or gum arabic and dextrines can be used. 
The present invention is illustrated in a more detailed manner by the 
following examples wherein the temperatures are indicated in degrees 
centigrade and the abbreviations have the meaning common in the art.

EXAMPLE 1 
Process for the preparation of 
(-)-(1'S,E)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one 
a. 150.6 g (0.83M) of methyl alpha-cyclogeranate in 1.5 l of anhydrous 
tetrahydrofuran (THF) have been treated at -10.degree. with 1.2 
equivalents of butyl-lithium. After having left the temperature to raise 
at about 15.degree., 1.35 equivalents of allyl-magnesium chloride in THF 
have been added to the reaction mixture and the resulting mixture has been 
left at 35.degree. for 30 min. 
b. The mixture was then cooled to -10.degree. and, at this temperature, 237 
g (1.5 equivalents) of (+)-(4S,5R)-1,5-dimethyl-4-phenyl-2-imidazolidone 
were added thereto in 1 mn and the mixture has been left for 30 mn at 
about -10.degree./0.degree., whereupon it was poured onto a mixture of 
NH.sub.4 Cl-ice. The organic phase after separation was washed with water 
and a saturated aqueous solution of sodium chloride, dried over anhydrous 
Na.sub.2 SO.sub.4, filtered and concentrated. The residue was diluted with 
30.degree./50.degree. petrol ether and filtered. The clear filtrate was 
evaporated and distilled over residue and a fraction having b.p. 
50.degree.-70.degree./10.6 Pa consisting of 
(-)-(1'S)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-3-buten-1-one was 
collected; [alpha].sup.20.sub.D (liquid)=-260.degree..+-.20.degree.. This 
fraction was then fractionnally distilled (b.p. 50.degree.-55.degree./10.6 
Pa), treated with alumina according to Reetz et al. [Chem. Ber., 118, 348 
(1985)] and redistilled over residue to give a fraction of 89 g of the 
desired ketone having a purity of 97% as indicated by gas chromatography 
([alpha].sup.20.sub.D =-280.degree..+-.20.degree. in CHCl.sub.3). By 
further purification of the obtained product, optically pure 
(-)-(1'S,E)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one 
having [alpha].sup.20.sub.D =-509.7.degree. (c=4.0 in CHCl.sub.3); 
m.p.=ca. 27.degree.) was isolated. 
By carrying out the reaction as indicated hereinabove and by replacing 
(+)-(4R,5S)-1,5-dimethyl-4-phenyl-2-imidazolidone by 
(1R,2S)-2-(N-methyl-N-isopropylamino)-1-phenylpropan-1-ol, the desired 
product was obtained with an [alpha].sup.20.sub.D 
=-340.degree..+-.20.degree. (c=6.4; CHCl.sub.3) before crystallization. 
EXAMPLE 2 
Process for the preparation of 
(-)-(1'S,E)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one 
10 g (66.6 mM) of 2,6,6-trimethyl-cyclohex-2-enylketene [see J. Org. Chem., 
42, 2111 (1977)] in 200 ml of anhydrous THF have been treated subsequently 
with 1.2 equivalents of allyl-magnesium chloride in THF [temp.: 
-78.degree..fwdarw.35.degree.; time: 30 mn] and at 20.degree. for 30 mn 
with 1 equivalent of lithium 
(1R,2S)-2-(N-methyl-N-isopropylamino)-1-phenylpropoxide [obtained by 
treating 1 equivalent of 
(1R,2S)-2-(N-methyl-N-isopropylamino)-1-phenylpropanol with 1 equivalent 
of n-butyllithium in THF], and finally with 2 equivalents of 
(1R,2S)-2-(N-methyl-N-isopropylamino)-1-phenylpropanol. The addition of 
this latter reagent occurs at a temperature of between -50.degree. and 
-10.degree. during 60 mn. The reaction mixture was poured into an icy 
aqueous solution of NH.sub.4 Cl and extracted with ether. The combined 
organic phases have been treated with a 5% aqueous solution of HCl, and 
the separated organic phases were washed with ether, treated with a 20% 
aqueous solution of KOH and extracted with ether to give an ether solution 
which, upon evaporation, gave 
(1R,2S)-2-(N-methyl-N-isopropylamino)-1-phenylpropanol. The mixture of the 
ketones obtained from the organic extracts was distilled in a bulb 
apparatus at 70.degree. and 0.5 Torr to give 9.7 g of a product which, by 
isomerization with alumina according to Reetz et al. [Chem. Ber., 118, 348 
(1985)], gave 9.3 g (73%) of 
(-)-(1'S,E)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one. 
[alpha].sup.20.sub.D =-396.degree. (c=4.0 in CHCl.sub.3). By further 
purification, the obtained product gave the desired ketone with an 
[alpha].sup.20.sub.D =-488.degree. (c=4.0 in CHCl.sub.3 ; m.p.: 
27.5.degree.-28.degree.). 
EXAMPLE 3 
Measure of the odor threshold 
Two samples consisting of 
(-)-(1'S,E)-1-(2',2',6'-trimethyl-2'-cyclohexen-1'-yl)-2-buten-1-one [or 
(S)-(-)-alpha-damascone] and of (R)-(+)-alpha-damascone, respectively, 
were submitted to a group of experts composed of 17 to 20 individuals for 
organoleptic evaluation. 
The two samples were evaluated in accordance with the method described by 
Guadagni [see Guadagni et al., J. Sci. Food Agric., 14, 761 (1963)]. The 
concentrations of the samples were set in decreasing order of magnitude so 
as to diminish the possible errors due to fatigue. The products were 
evaluated by dissolving them in natural mineral water. Each product was 
tasted at different dosages by comparison with a sample of water. Three 
evaluation sessions were effected in a one-week time interval so as to 
verify the reproducibility of the obtained results. 70% of the correct 
responses have been considered as meaningful for the assessment of the 
odor threshold value. 
The observed values were the following: 
(S)-(-)-alpha-damascone: 1.5 ppb (parts per billion) 
(R)-(+)-alpha-damascone: 100 ppb. 
EXAMPLE 4 
A base perfuming composition of floral type was prepared by mixing the 
following ingredients (parts by weight): 
______________________________________ 
Citronellol 150 
Phenyelthanol 150 
Terpineol 70 
Lilial (registered trademark).sup.1 
50 
Benzyl salicylate 100 
Trichloromethylphenylcarbinyl acetate 
30 
Cyclamen aldehyde 10 
Undecylenic aldehyde 10%* 
20 
Rose oxide.sup.2 10%* 20 
Purified indol 10%* 10 
Styrallyl acetate 10 
Linalol 80 
Total 700 
______________________________________ 
.sup.1 L. Givaudan; ptert-butyl-alpha-methyl-hydrocinnamic aldehyde 
.sup.2 Firmenich SA 
*in dipropylene glycol 
The above perfume base was then used to manufacture 4 new compositions by 
mixing the ingredients indicated below: 
______________________________________ 
A B C D 
______________________________________ 
Perfume base 70 70 70 70 
Dipropylene glycol 30 -- -- 
(RS)-alpha-damascone* 
-- 30 -- -- 
(S)-(-)-alpha-damascone* 
-- -- 30 -- 
(R)-(+)-alpha-damascone* 
-- -- -- 30 
______________________________________ 
*10% solution in dipropylene glycol 
These new compositions were then subjected to an odor evaluation by a group 
of experts. Their comments are given hereinbelow: 
Composition A: flat character, without defined rosy smell; 
B: pleasant rosy smell, slightly cork note, winey; 
C: fresh smell, well-defined rosy character in the direction of rose 
petals; the most pleasant of the four samples submitted; without secondary 
unpleasant character, the most powerful; 
D: the least interesting sample; marked "cork" note; chemical character. 
EXAMPLE 5 
Comparative aroma evaluation 
A comparative evaluation between the two optically active (R)-(+) and 
(S)-(-) enantiomers of alpha-damascones have been carried out by a group 
of experts composed of 10 individuals of both sexes. The two compounds 
have been tasted in a 1 ppm (part per million) solution of sugar syrup 
prior diluted to 10%. The two samples were judged as follows: 
(S)-(-)-alpha-damascone: woody, herbal, fruity (direction berries), cooked 
fruit, tobacco, tea, hay, dry leaves; 
(R)-(+)-alpha-damascone: hay, camphory, oily, fermented, hazelnut, dirty, 
without volume. 
EXAMPLES 6 TO 10 
EXAMPLE 6 
A commercial prune concentrated juice was diluted with mineral water and 
divided into 4 parts of equal volume: 
A: non aromatized reference sample; 
B: sample to which 0.5 ppm of (RS)-alpha-damascone were added; 
C: sample to which 0.5 ppm of (R)-(+)-alpha-damascone were added; 
D: sample to which 0.5 ppm of (S)-(-)-alpha-damascone were added. 
The four samples thus obtained were subjected to the evaluation of a group 
of flavor experts who had to express their opinion on their organoleptic 
properties. Their comments are summarized hereinbelow: 
A: typical prune character, rather flat, cooked fruit note; 
B: more fruity, juicy and rounded, fermentation character; 
C: more woody, dry fruit character, cardboard; 
D: even more pronounced dry fruit character, slightly caramel, more fruity; 
more distinct than B and C; has more character than A with a winey, rum 
note. 
EXAMPLE 7 
A commercial concentrated raspberry juice was diluted with mineral water 
and divided into 4 parts of equal volume. By proceeding as indicated in 
the example above, three samples containing (RS)-alpha-damascone, 
(R)-(+)-alpha-damascone and (S)-(-)-alpha-damascone, respectively, were 
prepared and compared to an unflavored juice sample. 
A: typical canned raspberry juice, cooked fruit note, rather flat; 
B: hay, camphory, possesses more fruity body, slightly earthy; 
C: similar to B, slightly camphory, good fruity note, the "jam" character 
is reinforced, better than A and B, slightly hay; 
D: more fruity, cooked fruit, more juicy and jammy, more typical berry, 
woody; more typical raspberry; this sample was preferred since its note 
was the nearest to the natural notes of raspberry. 
EXAMPLE 8 
100 ml of acidic sugar syrup were prepared by dissolving 8 g of sugar and 
0.1 g of citric acid in mineral water. The solution thus obtained was 
flavored with a concentrated strawberry flavor at a dosage of 0.05% by 
weight (origin: Firmenich SA) whereupon it was divided into 4 parts of 
equal volume. By operating as indicated in the above examples, the three 
samples of alpha-damascone under examination were evaluated at a 
concentration of 0.03 ppm. The comments of the flavor experts are 
summarized hereinbelow: 
A: fruity, strawberry jam, buttery; 
B: possesses more body than A, camphory, hay, fermented; 
C: more fruity than A and B, more marked jam character, cooked fruit; 
D: the most fruity, possesses a more marked character of red berries, more 
defined jam character; D is the preferred sample. 
EXAMPLE 9 
6 g of Ceylon tea leaves were used to prepare an infusion product by 
suspending them into 800 ml of boiling water. As indicated in the above 
examples, the infusion was divided into 4 equal parts and the three 
samples of alpha-damascone were compared at a concentration of 0.25 ppm 
with an unflavored control tea sample. 
A: unflavored tea beverage 
B: more fruity, apricot note, more floral, earthy; the odor has more impact 
than that of unflavored sample A; 
C: floral, more marked dry leaves character, slightly earthy, nutty; 
similar to sample A but possesses more flavor and impact; 
D: more marked aromatic tea character, dry leaves, hay, more fruity and 
sweeter; sample D is preferred, it shows the most typical black tea 
character. 
EXAMPLE 10 
A sample consisting of brand cigarettes manufactured with flue-cured 
tobacco was used for carrying out this evaluation. 
Three samples were flavored by the injection of a 95% ethanol solution of 
the three damascones under examination. As indicated above, sample A is 
the control unflavored cigarette, sample B was flavored with 
(RS)-alpha-damascone, sample C with (R)-(+)-alpha-damascone and sample D 
with (S)-(-)-alpha-damascone, each at a dosage of 12.5 ppm by weight based 
on the total weight of the tobacco. The samples were pre-conditioned by 
storing them during 48 hours. 
The smoke evolving by combustion of the cigarette samples under examination 
was evaluated organoleptically by a panel of flavor experts. By 
comparison, the odor perceived while opening the cigarette package is also 
indicated. 
Odor at the opening of the package: 
A: neutral, woody; 
B: fruity, slightly caramel, woody, fermented, more pronounced tobacco 
note; 
C: good tobacco head note, fruity, fermented, slightly floral; 
D: richer tobacco note, more fruity, more marked hay character. 
Smoke aroma: 
A: typical tobacco note; 
B: fuller character, more fruity, heavy, dirty after-taste; 
C: lighter, more herbal, hay, sweeter, more pronounced flue-cured 
character; 
D: richer, more pronounced tobacco character, more fruity, dry fruit type, 
than C, sweeter than A, possesses more body.