Polyunsaturated aliphatic esters as flavoring ingredients

Polyunsaturated aliphatic esters of new chemical structure find utility as flavor modifying agents. Flavoring compositions containing same and process for their preparation.

SUMMARY OF THE INVENTION 
The invention relates to a method for improving, enhancing or modifying the 
flavouring properties of foodstuffs and beverages which method comprises 
adding thereto an effective amount of a polyunsaturated aliphatic ester of 
formula 
##STR1## 
wherein symbol R represents a lower linear or branched alkyl radical 
having 1 to 3 carbon atoms and wherein the double bond at position 4 
possesses a cis configuration. 
The invention relates also to the compounds of formula (I), more 
particularly it relates to ethyl octa-cis4,7-dien-1-oate. 
The invention provides further a foodstuff or a beverage containing as 
flavouring active ingredient a compound of formula (I). 
The invention finally relates to a process for the preparation of the 
compounds of formula (I) which comprises the following subsequent steps: 
a. selectively epoxydizing cycloocta-1,5-diene to give 
1,2-epoxy-cyclooct-5-ene, 
b. oxidizing the thus obtained compound to give 
1-oxo-2-hydroxy-cyclooct-5-ene, 
c. treating said keto-alcohol with lead tetracetate in an ethanolic medium 
to give ethyl 7-formyl-hept-4-en-1-oate, 
d. reducing this latter by means of sodium borohydride, 
e. esterifying resulting ethyl 8-hydroxy-oct-cis4-en-1-oate to give ethyl 
8-acetoxy-oct-cis4-en-1-oate and 
f. subjecting said ester to pyrolysis to yield ethyl 
octa-cis4,7-dien-1-oate and, if desired, transesterifying the said ethyl 
ester to give the compounds of formula (I) wherein R represents an alkyl 
radical as defined above other than ethyl. 
THE INVENTION 
It has now been discovered that the compounds of formula (I) possess useful 
organoleptic properties and consequently they can be advantageously used 
in the flavour industry. Compounds (I) develop gustative notes of various 
nature, namely fruity, and they improve the natural character of exotic 
fruits, especially of pineapple, passion fruit or even orange. Owing to 
their specific properties, it is now possible to reconstitute more 
faithfully the natural taste and aroma of those fruits, namely the typical 
character of their juices. Compounds (I) can be used advantageously for 
the aromatization of foodstuffs and beverages of various nature, mainly, 
however, for the aromatization of dairy products, yogourths for instance, 
fruit juices and syrups. They can be used moreover as flavouring additives 
in bakery products, cakes or pastries, in jams, toffees or even 
chewing-gums wherein the fruity note is desired. 
Depending on the nature of the material it is desired to aromatize or on 
the effect desired, the proportions used may vary within a certain range. 
Typically, concentrations of from about 0.5 to 50 ppm (parts by weight per 
million) based on the weight of the flavoured material are satisfactorily 
used. It has to be understood however that said concentrations are not 
deemed to represent absolute values and proportions higher or lower than 
those given above may also be used. The compounds of the invention can be 
used on their own or, more frequently, in admixture with common edible 
solvents such as ethanol, dipropylene-glycol or triacetine, or on solid 
carriers such as gum arabic or dextrine. 
Among the compounds of formula (I), ethyl octa-cis4,7-dien-1-oate is 
preferred when used in accordance with the invention. 
Compounds (I) possess also perfuming properties and develop green, fresh, 
flowery and fruity odour notes. 
In accordance with the invention the compounds of formula (I) are prepared 
by the original process defined above, starting from cycloocta-1,5-diene a 
commercially available product. The process of the invention is 
illustrated by the following reaction pathway: 
##STR2##

The invention is better illustrated by but not limited to the following 
examples wherein the temperatures are indicated in degrees centigrade. 
EXAMPLE 1 
Ethyl octa-cis4,7-dien-1-oate 
1. 20 g of m-chloroperbenzoic acid (about 85%) in 1 lt of dichloromethane 
were added dropwise at about 5.degree. to a solution of 45 g of 
cycloocta-1,5-diene in 500 ml of dichloromethane. The reaction mixture was 
then kept 18 h at room temperature, then after filtration, washed with an 
aqueous solution of sodium sulphite, sodium carbonate and finally with 
water until neutrality. 
By evaporation of the volatiles followed by distillation there were 
obtained 32 g of a fraction having b.p. 41.degree./0.01 Torr. 
2. The thus obtained substance was dissolved in 150 ml of dimethylsulfoxide 
and a flow of air was bubbled during 27 h through the solution heated at 
110.degree.. The course of the reaction was followed by vapour phase 
chromatographic analysis. After cooling the reaction mixture was poured 
onto a mixture of ice-water and extracted with ether. The combined organic 
extracts were treated as usual by washing, drying, evaporating and 
distilling them. 
21 g of 1-oxo-2-hydroxy-cyclooct-5-ene having b.p. 
63.degree.-70.degree./0.05 Torr were thus obtained. 
IR: 3400, 1700 and 835 cm.sup.-1. 
NMR: 1.2-2.9 (8H, m); 3.4 (1H); 4.33 (1H, m); 5.65 (1H, m) .delta. ppm. 
MS: M.sup.+ =140 (3); m/e: 122 (16), 111 (18), 96 (60), 84 (56), 68 (95), 
67 (100), 54 (85), 39 (68), 27 (46). 
3. 80 g of lead tetracetate were added portion-wise under stirring at room 
temperature to a solution of 21 g of the hydroxy-ketone, obtained sub. 2, 
in 500 ml of a 3:7 mixture of ethanol and toluene. 
The addition lasted 15 minutes and the temperature of the mixture have 
increased up to about 35.degree., then the whole was left to rest for 11/2 
h. The mixture was filtered and the clear filtrate was washed with an 
aqueous solution of sodium bisulphite, sodium bicarbonate and a saturated 
aqueous solution of NaCl. On evaporation and distillation there were 
obtained 12.2 g of ethyl 7-formyl-hept-cis4-en-1-oate having b.p. 
120.degree./0.1 Torr. The purity of the product was of about 85%. 
IR: 2740, 1730 and 855 cm.sup.-1. 
NMR: 1.27 (3H, t, J=7 Hz); 1.5-2.7 (8H, m); 4.17 (2H, q, J=7 Hz); 5.4 (1H, 
m); 9.77 (1H, m) .delta. ppm. 
MS: M.sup.+ =184 (0); m/e: 141 (40), 110 (15), 95 (22), 81 (33), 67 (100), 
55 (49), 41 (69), 29 (67). 
4. A mixture of 7 g of the oxo-ester obtained as described above and 2 g of 
sodium borohydride in 50 ml of ethanol was kept under stirring at room 
temperature during 2 h. The reaction mixture was then poured onto ice, 
acidified and extracted with ether, then subjected to the usual treatments 
of washing, drying and evaporating. A bulb distillation of the residue 
gave 5.2 g of ethyl 8-hydroxy-oct-cis4-ene-1-oate having b.p. 140.degree. 
(bath temperature)/0.01 Torr. 
IR: 3450, 1740 and 855 cm.sup.-1. 
NMR: 1.23 (3H, t, J=7 Hz); 1.65 (2H, m); 2.02 (1H); 1.9-2.5 (6H, m); 3.67 
(2H, J=6 Hz, t); 4.13 (2H, q, J=7 Hz); 5.4 (2H, m) .delta. ppm. 
MS: M.sup.+ =186 (0); m/e: 156 (59), 140 (31), 123 (26), 110 (47), 97 (54), 
81 (92), 67 (100), 55 (58), 41 (76), 29 (83). 
5. A mixture of 4 g of the above obtained hydroxy-ester, 10 ml of acetic 
anhydride and 10 ml of pyridine was kept under stirring at room 
temperature during 2 h. The mixture was then directly subjected to 
pyrolysis at 450.degree. in a flow of nitrogen. The pyrolysate was 
dissolved in petrol ether and the solution thus obtained was washed with 
diluted aqueous HCl, sodium bicarbonate and water. The desired ester was 
purified by column chromatography on silica gel and bulb distillation and 
480 mg were thus obtained b.p. 72.degree.-78.degree./0.05 Torr. 
IR: 3080, 1735, 1640, 920 and 750 cm.sup.-1. 
NMR: 1.25 (3H, t, J=7 Hz); 2.38 (4H, m); 2.82 (2H, t, J=5 Hz); 4.14 (2H, q, 
J=7 Hz); 4.85-6.15 (5H, m) .delta. ppm. 
MS: M.sup.+ =168 (5); m/e: 122 (14), 94 (51), 80 (100), 79 (76), 67 (30), 
55 (19), 41 (41), 29 (38). 
EXAMPLE 2 
A base flavour composition of fruity type was prepared by mixing the 
following ingredients (parts by weight): 
______________________________________ 
Vanilline 20 
Sweet orange oil 40 
Lemon oil 10 
Amyl acetate 20 
Butyl acetate 30 
Ethyl propionate 30 
Ethyl butyrate 50 
Ethyl valerate 20 
Ethyl oenanthate 40 
Benzyl alcohol 200 
Propylene glycol 540 
1000 
______________________________________ 
By making use of the above base, two novel compositions were prepared as 
follows: 
______________________________________ 
Composition A 
Composition B 
(control) (test) 
______________________________________ 
Base composition 
100 100 
Ethyl octa-cis4,7-dien- 
1-oate -- 35 
95% Ethanol 900 865 
Total 1000 1000 
______________________________________ 
The novel compositions were subjected to an organoleptic evaluation in an 
acidified sugar syrup (prepared by dissolving 650 g of saccharose in 1000 
ml of water containing 10 ml of a 50% citric acid aqueous solution). The 
concentration was of 100 g of flavour composition per 100 l of acidified 
syrup. 
The test composition possessed a characteristic pine-apple note, which note 
was not present in the control composition.