DE2918747A1 - TRICYCLO-ALPHA, BETA-UNSATABLED KETONE - Google Patents

Description

Kao Soap Co., Ltd. May 9, 1979

Tokyo, Japan Our files: k 78-j, DE

Tricyclo-o ^ ß-unsaturated-ketones

The invention relates to new tricyclo-otjß-unsaturated-ketones of the following general formula (I):

(D

■ n

in which the Eest , 2

It ₁ -CH ₀ -CC = CH-

is bonded to the exo side of a norbornane ring in the 8- or 9-position, E _x and E ^ represent ^a hydrogen atom or an alkyl radical or alkenyl radical with Λ to 5 carbon atoms, at least one of E _x and E ~ Is hydrogen atom and the dashed line between the carbon atoms in the 3- and 4-position represents a saturated or ethylene-like unsaturated bond, ie this dashed line between the carbon atoms in the 3- and 4-position represents an optional double bond. The invention relates in particular 8- or 9 ~ exo-a, ß-unsaturated-ketone-

2 6 substituted endo-tricyclo [5.2.1.0 '] decane-3-ene, in which the dashed line between the carbon atoms in the 3- and 4-position is an unsaturated bond, or 8-exo-a, ß-

2 6 unsaturated-ketone-substituted endo-tricycloC5-2.1.0 '] -decane, where the dashed line between the

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Carbon atoms in the 3- and 4-positions are saturated Binding represents, the invention further relates to a process for the preparation of such ketones and their use in a perfume compositions containing such ketone.

It is known that some tricyclo [5-2.1.0 '] decane derivatives, which were obtained from endo-dicyclopentadiene, as odor-giving Ingredients for perfume compositions are useful as disclosed in Japanese Patent Publication No. 4-9-2534-0 and No. 51-9014, Japanese Patent Application Laid-Open No. 50-84558 and No. 52-70036 and U.S. Patent 3,270,061.

A wide variety of polycyclic compounds such as sesquiterpenes, diterpenes and adamantanes have been disclosed by the applicant synthesized, and it was found that a carbonyl radical is region-specific and stereospecific in the 8-position or 9-position on the exo side of a norbornane ring by an oxo reaction of endo-dicyclopentadiene in the presence an ehodium catalyst with the formation of 8- and 9-exo-formyl-

2 6
endo-tricyclo [5 · 2.1.0 '] deca-3-ene, as shown by the formulas (Ha) and (lib), is formed, these compounds having an aldehyde radical bonded to the exo side of the norbornane ring. This is in Synthetic Communications, 6_, (1976), 199 and Japanese Patent Application Laid-Open No. 52-68168.

OHC OHC

(Ha) '(Hb)

909847 / 07Q2 ORIGINAL INSPECTED

As a result of further investigations of the aforementioned 8- and 9-exo-formyl-endo-tricyclo [5 · 2.1.0 '] deca-J-ene, it has now been found that a tricyclo-ajß-unsaturated ketone of the formula ( I) by Aldo! Condensation of the compound of the formulas (Ha) or (lib) or of 8-exo-formyl-endo-tricycloC5.2.1.0 '] -decane, which is obtained by hydrogenating the aldehyde of the formulas (Ha) or (Hb ), with an aliphatic methyl ketone in the presence of a suitable catalyst to form an aldol condensation product, and can be prepared by subsequent dehydration of the product obtained, furthermore it was found that the compounds of the formula (I) have a woody odor. Therefore, perfume compositions can be prepared using at least one compound of the formula (I) as an odor-imparting ingredient.

The object of the invention is therefore to provide new tricyclo-ctjß-unsaturated-ketones of the formula (i) which are used as odor-giving Ingredients are beneficial, a method continues for the preparation of compounds of the formula (I) and the provision of new perfume compositions which stand out through a content of at least one compound of the formula (I).

According to the invention, therefore, there are new tricyclo-α-β-unsaturated ketones provided by the following general formula (I):

R _n -CH _n -CC = CH 1 2 ι.

where the rest

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ORIGiNAL INSPECTED

is bonded to the exo side of a norbornane ring in the 8- or 9-position, E ₁ and E _{2 represent} a hydrogen atom or an alkyl radical or alkenyl radical having Λ to 5 carbon atoms, at least one of E ₁ and E _{2 is} a hydrogen atom and the dashed line between the carbon atoms in the 3- and 4-positions represents either a saturated bond or an ethylene-like unsaturated bond.

The tricyclo-ctjß-unsaturated-ketones according to the invention represented by the formula (I) can be produced, for example, by aldol condensation of 8- or 9-exo-formyl-endo-tricyclo- ^ [5.2.1.O ² ' ⁶ ] deca-3- en or 8-exo-formyl-endo-tricyclo [5 * 2.1.0 deca-3-en or 8-exo-formyl-endo-tricyclo [5-2.1.0 '] -decane of the formula (III), these Compounds hereinafter also referred to as tricyclo aldehyde, can be prepared with an aliphatic methyl ketone of the formula (IV) in the presence of a catalyst and by dehydrating the condensation product, as shown in the following reaction scheme:

R CH,

OHC

Aldol condensate

(D

wherein:

R is the radical R ₁ CH ₂ - or R ₂ OH ₂ -, and E ₁ , E ₂ and a knitted! te line between the carbon atoms in the 3- and 4-Stellun, have the meanings given above.

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8- or 9-exo-formyl-endo-tricyclo [5 * 2.1.0 '] deca-3-en der Formula (Ha) or (lit) can be obtained by reacting endo-dicyclopentadiene (endo-TricycloC5 »2.1.0 '] deca-3,8-diene) with carbon monoxide and hydrogen in the presence of an ehodium triarylphosphine catalyst such as those in Synthetic Communications, 6_, (1976) 199 and Japanese Laid-Open Patent application no. 52-68168, which have already been mentioned above. The Bhodium triarylphosphine catalyst can, for example be a combination of the following formulas:

HRh (CO) (PE ^) ₅ XEh (CO) (PE ^) ₂ XEh (PE ₃ ),

where E is a phenyl radical or a phenyl radical substituted by an alkyl radical or an alkoxyl radical and X represents a halogen atom in the form of chlorine, bromine or iodine. The catalyst can be used in a catalytic amount and preferably in an amount of 0.01 to 1%, based on endo-dicyclopentadiene. The oxo reaction is. Preferably in an inert solvent, for example a hydrocarbon solvent such as benzene or toluene, or in an ether solvent such as ethyl ether or tetrahydrofuran, under a pressure of about 19.6 to 147
carried out.

19.6 to 147 bar at a temperature of about 50 to 150 ⁰ C.

8-exo-formyl-endo-tricyclo [5-2.1.0 '] decane, in which the dashed bond between the carbon atoms in the 3- or 4-position is saturated, ie represents a single bond and which is used as a starting material according to the invention can be made by hydrogenating 8- and / or 9-

2 6
exo-formyl-endo-tricyclo [5-2.1.0 '] deca-3-en of the formulas (Ha) and (Hb) can be prepared in the presence of a hydrogenation catalyst. The hydrogenation reaction is preferably carried out under a hydrogen gas pressure of 0.98 to 245 tar at a temperature from room temperature to about 100 ^° C. in an inert

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Solvent such as a hydrocarbon solvent, e.g. B. η-hexane or n-pentane, an aromatic hydrocarbon solvent, z. B. benzene, toluene or xylene, or an ethereal solvent, e.g. B. ethyl ether or tetrahydrofuran, with the addition of 1 / 10,000 to 1/100 mol of the aforementioned Ehodium catalyst carried out per mole of the olefinic aldehyde of the compound of the formulas (Ha) or (Hb).

The radical E. in the formula (I) represents a hydrogen atom or an alkyl radical having 1 to 5 carbon atoms. Suitable alkyl radicals for E ^ include, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, Isobutyl, tert-butyl, n-amyl, isoamyl and tert-amyl radical. Eg ^ ^{11 of} the formula (I) represents a hydrogen atom or an alkyl radical having 1 to 5 carbon atoms. Suitable alkyl radicals for Ep include alkyl radicals with low steric hindrance, e.g. B. the methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-amyl and isoamyl radical. At least one of E ^ and Ep in the compound of formula (I) should be a hydrogen atom.

Suitable, aliphatic methyl ketones of the general formula (IV ^ include, for example, acetone, 2-butanone, methyl isobutyl ketone, Methyl amyl ketone, allylacetone and 5-hexan-2-one.

When carrying out the method according to the invention, any] suitable catalysts including, for example, an acid catalyst such as hydrochloric acid to promote aldol condensation used v / earth. However, as an acid catalyst may cause the formation of by-products with the result of a lower yield, preferably becomes a strongly basic one Catalyst such as sodium hydroxide or potassium hydroxide or a strongly basic ion exchange resin is used. The starting material or the tricyclo-aldehyde of the formula (III) can be used in

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a ratio of 2: 1 to 1:50 mol relative to the aliphatic Methyl ketone of the formula (IY) and preferably used at a ratio of about 1: 1 to 1:10. A special one favorable molar ratio is about 1: 2.

The tricyclo-aldehyde of the formula (III) is combined with the aliphatic Methyl ketone reacted in a solvent such as water or a lower alkanol under reflux conditions. That Aldol condensation product is then converted into the compound of formula (I) by dehydration. The dehydration reaction can be done quickly and completely by adding a strong acid such as phosphoric acid, sulfuric acid or p-toluenesulfonic acid be carried out as an accelerator for dehydration in a catalytic amount.

In general, the aliphatic methyl ketone of the formula (IV) with the tricyclo-aldehyde of the formula (III) on the carbon atoms of an activated methyl or methylene group in Watchability condensed to the carbonyl group, where appropriate two types of compounds represented by formulas (Ia) and (Ib) are formed, see Organic Reaction, 16., (1968), 30,

R. 1

R ₉ I ²

CH ^ -CC = CH ³ II
O

(Ia)

(Ib)

wherein R _-1 , Ro and a dashed line between the carbon atoms in the 3- and 4-positions have the meanings given above.

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The equilibrium value for these condensation products varies depending on numerous factors including the catalyst, the substituent group, the solvent, the Reaction temperature and the like.

An aldehyde containing an active methine group as described by the tricyclo-aldehyde of the formula (III) as the starting material of the Process according to the invention is exemplified, is with the aliphatic methyl ketone of the formula (IV) mainly at the active methyl group reacted in the presence of a basic catalyst to the condensation product of the formula (Ia) - Using 2-butanone or 2-pentanone as the aliphatic methyl ketone creates a mixture of compounds of formulas (Ia) and (Ib). It is known that condensation in the presence of an acid catalyst is mainly occurs on the active methylene group of the aliphatic methyl ketone of the formula (IV), a compound of the formula (Ib ^ is obtained.

According to the invention, therefore, a compound of formula (Ia) or (Ib) or a mixture thereof depending on the Reaction conditions formed. Although this mixture is isolated and can be purified, such steps are not required when used as the odor component according to the invention will.

U.S. Patent 3,270,061 states that an aldol condensation product of 8-formyl-exo-tricyclo [5-2.1.0 '] -decane of formula (V) with an aliphatic ketone as odor component is useful, wherein the condensation product is a Stereoisomer of the tricyclo-aldehyde of formula (III) which is the starting material according to the invention:

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1.5 .- · ■■ - ■ .- ■

(V)

However, it should be pointed out that the aldol condensation product of the aldehyde of the formula (V) with an aliphatic methyl ketone is structurally different from the compounds of the formula (I) according to the invention. In the case of the aldol condensation product, such as it is described in U.S. Patent 3,270,061 is one Trimethylene bridge (carbon atoms in the 3-position, 4-position and 5-position) on the exo side of a urbornane ring and no configurations of a formyl group are described. It also requires the production of the aldehyde of formula (V) from endo-dicyclopentadiene some additional, complicated steps, which has the result that the aldol condensation product the compound (V) is expensive compared with the compound of the present invention.

Because of its characteristic, long-lasting odor, the compound of formula (I) according to the invention is an excellent one Odor ingredient for the production of perfume compositions for technical or industrial products such as detergents, Detergents, cosmetics, soaps, shampoo products, perfumes and the like.

The invention is explained in more detail below with the aid of examples.

example 1

Preparation of a mixture of 8- and 9-exo-formyl-endo-tricyclo-C5.2.1.O ² ' ⁶ Jdeca-3-en:

66 g = 0.5 mol endo-dicyclopentadiene, 100 ml benzene, 34-5 mg EhGl (CO) (PPH ^) ₂ and 0.25 ml triethylamine were in a

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- '16 -

Filled into the autoclave. The air in the autoclave was replaced with carbon monoxide gas. A mixture of carbon monoxide-hydrogen (molar ratio = 1: 1) was then introduced into the reaction mixture under a pressure of 98 "bar" at 70 ^° C. "until one equivalent of gas mixture had been absorbed. After cooling, the solvent was removed from the reaction mixture removed and the residue was distilled to give 66.4 g (yield 82%) of an oily mixture of 8- and 9-exo-pormyl-endo-tricyclo [5-2.1.0 '] deca-3-ene .

Example 2

Production of 8-exo-iOrmyl-endo-tricyclo [5.2.1.0 '] decane:

100 g of a mixture of 8- and 9-exo-JFormyl-endo-tricyclo- [5.2.IO '] deca-3-en, 1 g of tris-triphenylphosphine rhodium chloride and 150 ml of benzene were placed in an autoclave. Hydrogen gas was introduced into the mixture under a pressure of 4-9 bar at a temperature of 50 ° C. until the absorption of hydrogen ceased. After the reaction had ended, the benzene was removed under reduced pressure, giving 91.6 g (yield 90%) of 8-exo-formyl-endo-tricyclo [5.2.1.0 ² ' ⁶ ] decane with a temperature of 78 ° C / 2, 5 mbar (1.9 mm Hg) were obtained.

Elemental analysis for C. ^ H.gO:

calculated: C = 80.8 H = 9.6%

found: C = 80.5 H = 9.8%

IR spectrum (pure substance): 2950, 2860, 2800, 27OO, 1720,

14-50, 1050 cm " ¹

PMR spectrum (solvent CDGl ^, internal standard TMS):

1.2 - 2.7 (multiplet); 9.8 (CHO, singlet)

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Mass spectrum: m / e (relative intensity):

164 (M ⁺ , 6) 135 (65), 108 (25), 107 (60),

106 (16), 93 (19), 81 (16), 79 (29),

67 (100), 41 (39), 39 (24)

Example 3

Preparation of a mixture of 4- (endo-TricycloC5 «2.1.0 '] -deca-3-en-8-oxo-yl) -buto-3-en-2-one and 4- (endo-Tricyclo-C5.2.1 .0 ² ' ⁶ ] deca-3-en-9-exo-yl) -buto-3-en-2-one:

To a mixture of 2.0 g = 0.012 mol of a mixture of 8-

2 6 and 9-exo-iOrmyl-endo-tricyclo [5.2.1.0 '] deca-3-en and 20 ml Acetone were added dropwise with stirring at room temperature 0.5 ml of a 40% sodium hydroxide solution was added. To refluxing for 2 hours and then cooling 100 ml of ethyl ether were added to the resulting mixture at room temperature. The extract was saturated with Washed sodium chloride solution, neutralized with 5% hydrochloric acid solution and again with saturated sodium chloride solution washed. The organic layer was separated and dried over anhydrous sodium sulfate to give a Concentrated residue. This residue was distilled, yielding 2.06 g (yield 85%) of the aforementioned tricyclo-α, β-unsaturated-ketone were obtained in the form of a mixture.

Elemental analysis on C ^ ELgO:

calculated: C = 83.12 H = 8.97 %

found: C = 83.02 H = 8.95%

K. 92-97 ° C / 1.33 mbar

n§ °:. 1.5339

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ΙΕ spectrum: 3025, 1670, 1620 cm "" ¹

A perfume composition containing the product thus obtained "had a woody odor.

It has been found that this product consists of four isomers, since the starting material is a mixture of two positions isomers is used, which are also in the cis-Porm and trans-Porm because of the difference in the position functional groups or olefin carbon atoms on adjacent ones Carbonyl groups exist. The product is advantageously as a test ingredient without any Need for steps can be used for isolation and cleaning.

Example 4-

Preparation of 4— (endo-tricyclo [5.2.1.0 »] deca-8-exo-yl) -buto-3-en-2-one:

The same procedure was used as in Example 1 with the Au; would take repeatedly that 2.0 g of 8-exo-iOrmyl-endo-tricyclo [5-2.1.0 ' de can instead of a mixture of 8- and ^ exo-formyl-endotricyclo [5 «2.1.0 '] deca-3-en were used. There were 2.0 (yield 83%) of the aforementioned tricyclo-ocjß-unsaturatedj get ketones.

Elemental analysis on

calculated: C = 82.30 H = 9.87%

found: 0 = 82.57 H = 9.63%

K. 97-102 ⁰ O / 1.33 mbar

nJ5 °: - 1.5251

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ΙΕ spectrum: 1670, 1620 cm ¹

A perfume composition containing the product thus obtained possessed a woody-sword-lily-like odor.

Example 5

2 6 Preparation of a mixture of ^ - (endo-TricycloL 5 * 2.1.0 '] -deca-3-en-8- and -9-exo-yl) -3-methyl-buto-3-en-2-one and

O CL

1- (endo-Iricyclo [5> «2.1.0 '] deca-3-en-8- and -9-exo-yl) -penta-1-en-3-one:

A mixture of 2.0 g = 0.012 mol of a mixture of 8 and 9-exo-Eormyl-endo-tricyclo [5-2.1.0 '] deca-3-en and 20 ml of methyl ethyl ketone were prepared in the same manner as in Example 1 treated, with 2.15 g (yield 83%) of the aforementioned tricyclo-α, ß-unsaturated-ketones obtained in the form of a mixture became.

Element ar analysis on C ^ t-Hp ^ O:

calculated: C = 83.29 H = 9.32%

found: C = 83.47 H = 9.28%

K. 95-100 ⁰ C / 1.33 mbar

n ^ °: 1.5309

IR spectrum: 3025, 1670, 1625 cm " ¹

A perfume composition containing the product thus obtained had a honey-like, woody odor.

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Example 6

Preparation of 4- (endo-TricycloC5.2.1.0 '] deca-8-exo-yl) -penta-1-en-3 ~ one:

A mixture of 2.0 g = 0.012 mol of 8-exo-lormyl-endo-tricyclo-C5.2.1.0 ² ' ⁶ ] decane and 20 ml of methyl ethyl ketone was treated in the same way as in Example 1, with 2.12 g (Yield 81 %) of the aforementioned tricyclo-α, β-unsaturated ketone was obtained in the form of a mixture.

Element ar analysis on C ^ tE ^^ ⁵

calculated: C = 82.52 H = 10.16%

found: G = 82.38 H = 10.29%

K. 102-105 ° C / 1.33 mbar

χξ ° : 1.5246

IR spectrum: 1660, 1630 cm " ¹

A perfume composition containing the product thus obtained had a sword-like, woody odor.

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Claims (12)

Lorenz '& Riederer Patent attorney Lorenz & Riederer, Postfach 1320, D-8035 Gaming 2 Dipl.-Phys. Willy Lorenz Dipl.-Ing. Anton Frhr. Riederer by couple Kao Soap Go., Ltd. 1-1, Nihonbashi Kayaba-cho, Chuo-ku, Eokio, Japan Tricyclo-α, B-unsaturated e-ketones May 9, 1979 Our files: k Claims 1. Tricyclo-ajβ-unsaturated-ketones of the following general - 'Formula (I):. '10 R ₁ -CH ₂ -CC = CH (I) E ~ in which the Eest is gebtinden on the exo side of a UorlDornanring in the 8- or 9-position, E ^ and E _{2 represent} ^a hydrogen atom or an alkyl radical or alkenyl radical with Λ to 5 carbon atoms, at least one of the E groups, and Eo is a hydrogen atom and the dashed line between the 909847/0702 Carbon atoms in the 3- and 4-positions are saturated or represents an ethylene-like unsaturated bond. 2. Tricyclo-a, ß-unsaturated ketones according to claim 1, characterized in that the alkyl radical for the radical E. in the formula (I) is a methyl, ethyl, n-propyl, isopropyl, η-butyl -, isobutyl, tert-butyl, n-amyl, isoamyl or tert-amyl radical, and that the alkyl radical for the radical R ₂ in the formula (I) is methyl, ethyl, n-propyl -, isopropyl, n-butyl, isobutyl, n-amyl or isoamyl radical or R ₂ ^e ^ - ^{n is} hydrogen atom. 3. Process for the preparation of Tricyclo-oc ^ -unsaturated ketones of the following general formula (I): wherein the remainder Rq R-CH ₀ -CG = CH- I ζ- ii
0 is bonded to the exo side of a norbornane ring in the 8- or 9-position, R ^ and R _{2 represent} a hydrogen atom, an alkyl radical or alkenyl radical with Λ to 5 carbon atoms, at least one of the radicals R ^ and R _{2 is} a hydrogen atom and the dashed line between the carbon atoms in the 3-position and 4-position represents a saturated bond or an ethylene-like unsaturated bond, characterized in that 8- or 9-exo-formyl-endo-tricyclo [5 «2.1.0 ' ] deca-3-en or & 09847 / Θ702 general formula (III) 10 OHC .IO ' ⁶ ] decan the following (III) wherein the dashed bond between the carbon atoms in the 3- and 4-positions has the meaning given above with an aliphatic methyl ketone represented by the following general formula (IV) 11 . where B. denotes the radical E.CHp- or Rp ^GH 2 """is condensed in the presence of an aldol condensation catalyst to produce an aldol condensation product, and this condensation product is then dehydrated. 4 ·. Method according to claim 3 * characterized in that as aliphatic methyl ketone acetone, 2-butanone, methyl isobutyl ketone, Methyl amyl ketone, allyl ketone or 5-hexan-2-one are used will. 5. The method according to claim 3 »characterized in that as Aldol condensation catalyst a strongly basic catalyst is used. 909847/0702 6. The method according to any one of claims 3 or 4, characterized in that the reaction in a ratio of 2: 1 to 1:50 mol of the 8- or 9-exo-i \ Drmyl-endo-tricyclo [5 «2.1. 0 '] deca-3-ensoder 8-exo-Ii ^l ormyl-endo-tricycloE5.2.1.0' is performed] decane to the aliphatic methyl ketone. 7- method according to claim 3? characterized in that the Reaction in a solvent under reflux "at The boiling point of the solvent is carried out. 8. The method according to any one of claims 3 "to 7» characterized in that that water or a lower alkanol is used as the solvent. 9. The method according to claim 3, characterized in that the dehydration in the presence of a strong acid as a dehydration accelerator is carried out. 10. The method according to any one of claims 3 or 9 *, characterized in that that phosphoric acid, sulfuric acid or p-toluenesulfonic acid is used as the strong acid. ' 11. The method according to any one of claims 5> 9 or 10, characterized in that the strong acid in an equivalent Amount is added to the catalyst. 12. Process for the preparation of tricyclo-α-β-unsaturated ketones of the following general formula (Vl) 10 R ₁ -CH ₀ -CC = CH 1 2 η (VI) O 909847/0702 in which the Eest R.-CH ₀ -CC = CH- I C- Il is bonded to the exo side of a norbornane ring in the 8 or 9 position and R _x and R _{2 are} a hydrogen atom. denote an alkyl radical or an alkenyl radical having 1 to 5 carbon atoms, characterized in that (a) endo-dicyclopentadiene with carbon monoxide and hydrogen in the presence of a rhodium-triarylphosphine catalyst for the preparation of 8- or 9-exo-pormyl-endo-tricyclo- [5.2.I.O 'ldeca-3-en is implemented, (b) this 8- or 9-exo-JOrmyl-endo-tricyclo [5.2.1.0 ' 1- deca-3-ene with an aliphatic methyl ketone of the following general formula (IV) Il wherein R is the radical R ^ CH ₂ - or R ₂ CH ₂ -, is condensed in the presence of an aldol condensation catalyst to produce an aldol condensation product, and
(c) this condensation product is dehydrated. Process for the preparation of tricyclo-av [beta] unsaturated ketones of the following general formula (VII) (VII) 909847/6702 T? where the remainder, 2 R.-CH ₀ -CC = CH- is bonded to the exo side of a norbornane ring in the 8-position, and E. and R _{0 represent} a hydrogen atom, an alkyl radical or an alkenyl radical having 1 to 5 carbon atoms, characterized in that (a) endo-dicyclopentadiene with carbon monoxide and hydrogen in the presence of a rhodium-triarylphosphine catalyst for the preparation of 8- or 9-exo-eormyl-endotricyclo [5.2.1.0 '] deca-3-en is implemented, 2 6 (b) this 8- or 9-exo -]? ormyl-endo-tricyclo [5 «2.1.0 '] - deca-3-en in the presence of a hydrogenation catalyst for the production of 8-exo-iOrmyl-endo-tricyclo [5-2.1.0 ' decane is hydrogenated, (c) this 8-exo-formyl-endo-tricyclo [5 · 2.1.0 '] decane with an aliphatic methyl ketone represented by the following general formula (IV) II wherein R is the radical R ^ CHo- or RoCH ₂ - is condensed in the presence of an aldol condensation catalyst to produce an aldol condensation product, and
(d) this condensation product is dehydrated. 909847/0702 copy ^?