JPS6050771B2 - Method for producing methyl-norbornene derivative - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides compounds of the following formula (I), 6, (I) (wherein the methyl group is substituted at any of the 1', 4', 5' or 6' positions of the ring). This invention relates to a method for producing a novel methyl-norbornene derivative represented by

Compound I obtained according to the present invention is an important compound as a fragrance having a sanguine aroma.

Natural sandalwood oil is an oil obtained by steam distilling the heartwood and roots of sandalwood trees grown in the Malay region of India, and is an important flavoring agent for oriental flavor preparations. However, sandalwood is a special plant that produces suckers that are longer than its roots and grows as a parasite on the roots of other trees, and it takes 3 Cyjf- to cultivate it from seed and collect sandalwood oil, which is why sandalwood is a special plant that produces suckers that are longer than its roots and grows as a parasite on the roots of other trees. However, these resources have become scarce and have been in short supply in recent years, making them expensive. In addition, the main component of natural sandalwood oil is α,β-santalol, but the industrial production method for this has not been successful, so it is naturally desirable to develop a synthetic fragrance with a similar aroma.
Although there are several products on the market that are similar in odor to sandalwood oil but have a completely different structure, these too do not satisfy the public demand in terms of price and fragrance. Therefore, as a result of intensive research in order to meet such demands, the present inventors have developed a novel formula (I) which has an aroma similar to α9β-santalol from methylcyclopentadiene using an industrially easy method. succeeded in synthesizing the compound.

The production method of the present invention is shown in reaction formula 2 as follows.

That is, in the present invention, methylcyclopentadiene (2) and acrolein (2) are reacted by a Diels-Argout reaction to form an adduct (2), diethyl ketone (2) is condensed with this in the presence of an alkali, and then this product (2) is converted into an adduct (2). This is a method for producing methyl-norbornene derivative 1 by reduction.

Methylcyclopentadiene used as a raw material in the present invention is an unstable compound and is usually commercially available as a dimer.

If this dimer is heated to 180°C, it will form a 2-methyl form and a 3-methyl form.
Although a mixture of -methyl compounds with a ratio of 1:1 is obtained, it is difficult to separate these even by distillation or the like.

(■.A. MIRONO■ etc. ``TetrahedrO
n゛VOl. 19, ppl939) However, in the present invention,
This mixture can be used to achieve the objective, and hereinafter a 1:1 mixture of 2-methyl and 3-methyl is simply referred to as methylcyclopentadiene. In the present invention, first, methylcyclopentadiene and acrolein are reacted by a Diels-Alder reaction to obtain an adduct.

It is composed of a mixture of adducts as shown in the following reaction equation. Although these are difficult to separate, industrially they can only be used as a mixture to achieve the purpose of perfumery.

The Diels-Alder reaction was described by R. Adams4'0rg
anicReacti0ns″VOl,■,SecOn
It can be carried out under the reaction conditions described in dprinting ■Y, 1949, pp. 89-90. That is, simply mixing equimolar amounts of both compounds at room temperature will proceed with heat generation, so the mixture is cooled and kept at room temperature. As the solvent used in this step, benzene, toluene, diethyl ether, and tetrahydrofuran can be used. Next, this adduct and diethyl ketone are condensed in the presence of an alkali to obtain a ketone compound (1). The condensation is carried out in a solvent such as methanol in the presence of an alkali such as caustic soda or caustic potash.
This is done by heating under reflux for an hour. Diethyl ketone is used in an amount of 2.5 to 3 equivalents based on the adduct. Caustic alkali is used in an amount of 114 equivalents based on the adduct, and it is preferable to use a 0.3N methanol solution of caustic alkali. After the reaction, methanol is recovered under reduced pressure, the concentrate is dissolved in ether, washed with saturated brine, the ether is distilled off, and the residue is distilled under reduced pressure to obtain a ketone compound. Ketone compounds consist of a mixture of isomers, but it is difficult to separate these isomers, and industrially there are compounds that can be used in the form of mixtures for perfume purposes. Next, the carbonyl group of the ketone compound is reduced using sodium borohydride or lithium aluminum hydride to obtain the desired methyl-norbornene derivative.

Yang combination using sodium borohydride uses 1.5 equivalents of sodium borohydride to the ketone compound (corresponding to 0.38 mol to 1 mol of the ketone compound),
The reaction is preferably carried out in aqueous methanol, and caustic alkali is added to prevent decomposition of the sodium borohydride.
Caustic alkali is 10 to 10% of sodium borohydride.
It is sufficient to use 15% by weight. Methanol is used in an amount of at least 1.5 to 2 times the amount of the ketone compound. The higher the number, the better. Water is used to the extent that methanol becomes 75% aqueous methanol. React by keeping at about 400C for 1.5 to 2 hours.

After completion of the reaction, methanol is recovered under reduced pressure, the residue is dissolved in toluene, washed with saturated brine, the toluene is distilled off, and the target compound is purified by distillation under reduced pressure. When using lithium aluminum hydride to reduce a ketone compound, the amount of lithium aluminum hydride used is 1.5 equivalents (equivalent to 0.38 mol per 1 mol of the ketone compound), and 10 times the amount of anhydrous diethyl ether is used as a solvent. The reaction is carried out at 5-10°C under ice cooling.
After the reaction is complete, water is added to decompose excess lithium aluminum hydride, the ether layer is dried over anhydrous sodium sulfate, the ether is distilled off, and the target compound is obtained by distillation under reduced pressure. The methyl-norbornene derivative thus obtained is 1-('-methylnorbornene-5''-ene-2''-
yl)-2-methylbent-1-en-3-ol, 1
-(5'-methylnorborne-5'-en-2''-yl)-2-methylbent-1-en-3-ol, 1-(
4″-methylnorborne-5′-en-2″-yl)-
2-Methylbent-1-en-3-ol, 1-(6″
-methylnorborne-5''-en-2'-yl)-2-
a mixture of methylbent-1-en-3-ol;
The aroma of these compounds is similar to α,β-santalol, which is the main component of sandalwood oil,
These compounds can be industrially advantageously used as a fragrance component in the form of a mixture without being separated into individual components.

Next, an example will be given and explained.

Example 1 (1) 400 y of methyl-cyclopentadiene and 1 q of hydroquinone were placed in a 3e reaction flask, and 311 d of acrolein and 440 d of tetrahydrofuran were added to the flask while stirring on ice.
The mixture of m1 was added dropwise over 2 hours while the internal temperature was maintained at 25 to 30°C, and the 15I Terama reaction was further carried out at the same temperature.

After the reaction was completed, the contents were transferred to a distillation flask, and after distilling off tetrahydrofuran, it was distilled under reduced pressure to 70-72°C/15T!
A fraction of UnHg, namely methylcyclopentadiene and acrolein. An adduct of 658.1y was obtained. This product was IR (1710 cm-1,715 cTt-1). (Ii) 1.2e methanol in 3' reaction flask
, 40% caustic soda solution 50y1 diethyl ketone 430
Add y and heat to reflux at 62°C.
40y was added dropwise to the mixture, and the mixture was further heated under reflux for 2 hours. Methanol was distilled off under reduced pressure, and 50% of ether was added to the concentrate.
0ml was added and dissolved, and the mixture was washed three times with 300ml of saturated saline. Pour the ether solution into a distillation flafco, distill off the ether, and then distill under reduced pressure to achieve a temperature of 91-93°C/2.0T! RmH
A fraction of g, a ketone compound, 233y was obtained. This one is IR (1660c7!-1,710c71-1
). (Iii) 11 Put the ketone compound 204q1 obtained above, 224ml of methanol, 8y of 15% caustic potassium into a reaction flask, heat to 40°C while stirring, and add 14.2y1 of sodium borohydride, 0.88y of caustic potassium, 112ml of water, and 112TIL of methanol. The solution was added dropwise over a period of 1 hour, and the mixture was stirred for an additional 3 times.

After the reaction, methanol was distilled off and concentrated under reduced pressure, 300 ml of toluene was added to the concentrated solution to dissolve it, and the toluene solution was washed twice with 300 ml of saturated brine. The toluene solution was transferred to a distillation flask, toluene was distilled off under reduced pressure, and the residual liquid was distilled under reduced pressure to obtain fraction 143y of 80-8rc/1.07T0nHg. The IR and NMR spectra of the methylnorbornene derivative thus obtained are shown in Figures 1 and 2.
As shown in the figure. ≧Example 1 The methyl-norbornene derivative obtained in Example 1 is
Manufacture soap fragrance according to the following recipe.
Part by weight Compound obtained in Example (1) 150 Cedrol
100 ethylene brush rate
120 musk ketones
30 Benzyl salicylate 6
0 isoamyl salicylate 40 methyl ionone 70 p-t-butylcyclohexyl acetate 150 dimethylbenzyl carbinyl acetate 20 α-hexyl cinnamic aldehyde 50 indole (10%)
20 Benzyl acetate 50
Styraryl acetate 40 Aldehyde ClO2 Aldehyde Cl 39 -Decenol 15 Lavandein oil 90 This product has an oriental type aroma, with a childish top note and strong aroma retention.

[Brief explanation of the drawing]

FIG. 1 shows the IR spectrum of the methyl-norbornene S conductor obtained in Example 1, and FIG. 2 shows the JMR spectrum of the same compound.

Claims (1)

[Claims] 1. Reacting methylcyclopentadiene and acrolein by Diels-Alder reaction to form an adduct, condensing diethyl ketone with this in the presence of an alkali,
Then, the following equation (
I), ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, the methyl group indicates that it is substituted at the 1', 4', 5' or 6' position of the ring.) A method for producing the represented methyl-norbornene derivative.