Diene compound and process for producing the same

Details Diene compound and process for producing the same Diene compound and process for producing the same

1999-08-26

2001-05-29

Richter, Johann (Department: 1621)

Chemistry of hydrocarbon compounds

Aromatic compound synthesis

By condensation of entire cyclic molecules or entire...

C585S429000, C585S434000, C585S438000, C560S243000, C560S244000, C568S450000

Reexamination Certificate

active

06239324

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to diene compounds, in particular, co-dimer diene compounds. These compounds are prepared through the reactions of conjugated diene compounds with vinyl esters in the presence of a ruthenium salt. The invention especially relates to a chain co-dimer diene compound which is a promising raw material for preparing terpenes. Chain co-dimer diene compounds are obtained by reacting a 2-substituted-1,3-butadiene (a conjugated diene part) with a compound having a double bond at its terminal (a vinyl ester part). The invention also relates to a method of producing these co-dimer diene compounds.
Typical conjugated dienes used in the invention include isoprene and myrcene. The isoprene is reacted with a vinyl ester to prepare 4-methyl-5-hexen-1-al, which is a useful perfume material and can be used in a perfume composition. The invention relates also to this aspect.
Likewise, myrcene gives rise to 4-vinyl-8-methyl-7-nonenal which is also a useful perfume material. The invention relates therefore to 4-vinyl-8-methyl-7-nonenal, a method of production thereof and a perfume composition prepared therefrom. The 4-vinyl-8-methyl-7-nonenal has a strong, aliphatic aldehyde-like fragrance, emanating a citrus—as well as rose-like scent, and can be used as perfumes or in perfume compositions.
2. Description of Related Art
Generally, a small difference in chemical structures among compounds gives rise to a considerable difference in fragrances of the compounds and the other related properties, e.g. retentivity and volatility. The search for new perfumes involves therefore an important workload in such fields as synthesis of various compounds and tests of their fragrance. Among these compounds, aliphatic aldehydes are known as a useful source for perfume essence materials. From this viewpoint, many aldehydes have been produced and put to actual use (Motoichi INDO, “Synthetic Perfume”,
Chemistry and Product Information,
1996, published by Kagaku Kogyo Nippoh). For instance, melonal, citral and citronellal emanate a green melon-like, lemon-like and hawthorn-like fragrance, respectively, and give a specific scent to perfume compositions. They are therefore widely used as a blending essence for a perfume.
As for 4-methyl-5-hexen-1-al, a method of its production from citronellal is reported in
J. Org. Chem.,
Vol. 42, pp. 3622, 1977. This method has the disadvantage of involving many steps and incurring high production costs. Moreover, there has been no description on the fragrant characteristics of 4-methyl-5-hexen-1-al, nor on its use as perfume compositions. Cis-3-hexenal, a compound similar to 4-methyl-5-hexen-1-al, is very expensive, and trans-2-hexenal, another similar compound, has a strongly irritant odor.
In order to form a carbon-carbon bond with butadiene or substituted butadienes efficiently, methods involving a Diels-Alder reaction (B. M. Trost et al.,
Angew. Chem. Int. Ed. Engl.,
Vol. 34, pp. 259 (1995)) and reactions with a triple bond (T. Mitsudo et al.,
J. Org. Chem.,
Vol. 50, pp. 565 (1985)) have been well-known.
All these methods, however, have the disadvantages that the conjugated double bond of butadienes or its counter part compound must be activated and the regioselectivity cannot be controlled.
Moreover, these methods are susceptible to forming ring products, which is a handicap for the synthesis of chain terpene.
Meanwhile, organometallic reagents have been widely used in reactions for synthesizing carbon-carbon bonds, so as to form desirable skeletons selectively (Japanese Patent Application Laid-Open (JP-A) No. H3-148228). However, these reactions not only involve use of a cumbersome organometal in a stoichiometric amount but also requires the so-called “elimination group”, namely, a functional group which does not participate in the structure of the resultant product. This is a disadvantage from the industrial and environmental points of view, and the reactions become costlier. It is therefore desirable to develop a novel route for synthesizing a carbon-carbon bond. This novel route should involve the reaction which does not require any elimination group, and may proceed on a catalytic basis.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a compound having a mild fragrance without emanating irritant odor. Another object of the invention is to provide a method of preparing such a compound, the method involving reduced process steps. The compound can thus be produced at lower costs. A further object of the invention is to provide a perfume composition comprising such a compound.
In view of the above, there has been conceived a novel method of forming a carbon-carbon bond in a regioselective manner through a catalytic reaction. This method allows preparing new diene compounds which provide promising raw materials for the production of terpene.
After extensive studies, the present inventors found that a novel co-dimer diene compound having a desirable regioselectivity can be obtained by reacting 2-substituted-1,3-butadienes with an olefin compound having a double bond at its terminal position (hereinafter referred to as “terminal olefins”) in a hydrophilic solvent, in the presence of a ruthenium catalyst, and thus completed the present invention.
A first aspect of the invention concerns a process for producing diene compounds from 2-substituted-1,3-butadienes and terminal olefins. This object required the discovery of a novel carbon-carbon bond-creating reaction which proceeds on a catalytic basis. The process provides a novel compound useful as a perfume component.
A second aspect of the invention relates to a diene compound represented by the following general formula (IX):
wherein R
1
represents a hydrogen atom, a C
1
-C
6
alkyl group which may have a substituent or a C
2
-C
6
an alkenyl group which may have a substituent and R
2
represents a phenyl group which may have a C
1
-C
4
lower alkyl group or a C
1
-C
12
acyloxy group which may have a phenyl group, a naphthyl group or a benzyl group or R
2
is a hydroxy group which reversibly forms an aldehyde group through shifting of the position of the double bond adjacent said hydroxy group.
A third aspect of the invention is concerned with 4-methyl-5-hexen-1-al represented by the formula (X):
This product can be obtained easily at low costs by hydrolyzing a compound represented by the formula (IX):
in which R
1
is a methyl group, and R
2
represents a C
1
-C
12
acyloxy group which may have a phenyl group, a naphthyl group or a benzyl group or R
2
is a hydroxy group which reversibly forms an aldehyde group through shifting of the position of the double bond adjacent said hydroxy group; the wavy line shows cis-isomer, trans-isomer,or a mixture thereof.
4-Methyl-5-hexen-1-al has a high level of fragrance which is easily diffusible, and contains a strongly fresh and green fruit-like scent. This aldehyde compound is milder, less irritating and more fruity in comparison with similar perfume compounds such as cis-3-hexenal and trans-2-hexenal.
A fourth aspect of the invention relates to 4-vinyl-8-methyl-7-nonenal (XI) and a method of preparing this compound from myrcene (VIII), one type of 2-substituted-1,3- butadienes. 4-Vinyl-8-methyl-7-nonenal (XI) gives a strong, aliphatic aldehyde-like fragrance, emanating a citrus—as well as rose-like scent, and thus provides a useful perfume essence material. The product (XI) is also suitable for use as a perfume composition.
To the above-mentioned end, there is first provided a process for producing a diene compound at least comprising the step of reacting 2-substituted-1,3-butadienes represented by the following general formula (I):
wherein R
1
represents a hydrogen atom, a C
1
-C
6
alkyl group which may have a substituent or a C
2
-C
6
alkenyl group which may have a substituent;
with terminal olefins represented by the following general formula (II):
wherein R
2
represents a phenyl group which may have a C
1
-C
4
lower alkyl group, or a C
1
-C
12
acyloxy grou

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