JPS6024085B2 - Method for producing dihydrotagetone using metaacrolene acetal as raw material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing dihydrotagetone using metaacrolene acetal as a raw material.

This dihydrotagetone (2,6-dimethyl-7-octen-4-one) is
It is contained in the essential oil of the lifera, and it is included in the essential oil of
It is known as a compound that characterizes the scent of this flower, along with dimethyl-5,7-octadieth-4-one).

Conventionally, this dihydrotagetone has been synthesized by the methods shown in [1' to '4' below.

However, these conventional synthesis methods require long steps and use oxidation reactions and Grignard reactions, so they cannot be said to be industrially advantageous.

The present inventor has discovered that it is possible to produce dihydrotagetone industrially advantageously.
The present invention was completed by obtaining -ketoaldehyde and discovering a method for synthesizing dihydrotagetone therefrom. That is, the present invention produces y-keto aldehyde acetal {C' by the radical addition reaction of metaacrolene acetal and 3-methylbutanal [8', as shown in formula [5}, Aldehyde acetal 'C' is hydrolyzed to give a y-ketoaldehyde plate, and then dihydrotagetone [F' is produced by Wittig reaction of this y-ketoaldehyde plate with methylene triphenylphosphorane.

CH2C (CH8>CH.C2day5>2 Hereinafter, the present invention will be specifically explained based on experimental examples.

First, the process of obtaining y-ketoaldehyde acetal } by the reaction of meta-acrolene diethyl acetal with 3-methylbutanal 'B} will be described. Into a flask equipped with a base mill, a thermometer, a dropping funnel, and a reflux condenser was added 7.2 mL of methachlorondiethyl acetal (0.0 mm, 0.0 mm,
ol) and 3-methylbutanal (17.2 ol) and 3-methylbutanal (0.2
hol) and heated to 85 to 90 degrees under a stream of dry nitrogen.

Among these, metaacrolene dityl acetal 7.2 (0.08nol), 3-methylbutanal 17.2
(0.2 hol) and penzoyl peroxide 0.5 hol (0
．． A solution of 002 hol) was added dropwise over 2 hours, and the incubation was continued for 8 hours while maintaining the above temperature. After the reaction mixture was cooled to room temperature, it was poured into a 5% aqueous sodium carbonate solution of 100 M and extracted with Enal. Then, after washing the ether layer with saturated saline, sodium sulfate (anhydrous)
Dry and remove from ether. The residual oil is distilled under reduced pressure to bp
91-9 obtained 11.3 fractions of Hg on the 0/4 side. This fraction showed a single peak on gas chromatography,
It was confirmed by IR spectrum, NMR spectrum, and MS spectrum that it was 1,1-diethoxy-2,6-dimethyl-4-heptanone (y-ketoaldehyde acetal'q). The yield at this time was 49%. Incidentally, instead of the above-mentioned penzoyl peroxide, Q.Q-azobisisobutyronitrile could be used as an initiator, and the yield in that case was 48%.

Also, the relationship between reaction time and yield in this reaction is as shown in the figure, and as can be seen from this figure, the reaction time is 1
The feeding time was optimal, and further reaction did not improve yield. Furthermore, we investigated the relationship between the ratio of raw materials and the yield in this reaction, and found that the optimal ratio of metaacrolene diethyl acetal/3-methylputanal [B] was 1'4. Further increases in '81 did not improve the yield.

Next, a method for producing y-ketoaldehyde (2) from y-ketoaldehyde acetal (2) will be described.

Into a flask equipped with a dropping funnel and a screen strainer, 23.0 g (0.1 mol) of y-ketoaldehyde acetal (0.1 mol) and 100 g of acetone are placed, and 20 g of a 10% aqueous sulfuric acid solution is added dropwise at room temperature.

After the mixture was heated at room temperature for 4 hours, the reaction solution was poured into 200ml of 5% aqueous sodium bicarbonate solution to separate it into an oil layer and an aqueous layer. After the aqueous layer is extracted with ether, the ether layer and oil layer are combined, washed with saturated brine, and dried over sodium sulfate (anhydrous). After that, the ether was removed, and the remaining oil was distilled under reduced pressure.
A fraction of 14.4 g was obtained. This fraction showed a single peak in gas chromatography, IR spectrum, NM
2,5-dimethyl-4-oxoheptanal (y-ketoaldehyde style) by R spectrum and MS spectrum.
It was confirmed that At this time, the yield was 92%.

Furthermore, a method for preparing dihydrotagetone by Wittig reaction of a y-ketoaldehyde plate and a methylene triphenylphosphorane leg is described.

y in a flask equipped with a reflux condenser, a crossing device, and a dropping funnel.
- Put 9.4 liters (0.08 hol) of ketoaldehyde and 30 liters of dry benzene into it, and dropwise add a benzene solution of methylene triphenylphosphorane prepared in advance at room temperature under a nitrogen atmosphere.

After heating at the above temperature for 4 hours, the reaction solution was poured into saturated brine to separate into an oil layer and an aqueous layer. This oil layer is dried over sodium sulfate (anhydrous), and after distilling off the benzene, 200% of hexane is added and the salt is filtered off. Thereafter, the hexane was distilled off, and the residual oil was distilled under current pressure to obtain a product with a BP of 65 DEG C./22 Hg. This crab substance showed a single peak in gas chromatography, and it was confirmed to be 2,3-dimethyl-7-octen-4-one (dihydrotagetone side) by the melon spectrum, NM old spectrum, and MS spectrum. did. The yield at that time was 65%.

Incidentally, methylenetriphenylphosphorane, which is a raw material for the above reaction, can be easily obtained, for example, as follows.

That is, in a flask equipped with a reflux condenser and a lamp, 24.2 hours (0.2 hours) of methylene triphenylphosphonium iodide was added.
08 hol), sodium amide 2.9 hol (0.072
hol), 200 g of dry benzene was added thereto, and the mixture was refluxed for 6 hours under a stream of dry nitrogen. Thereafter, the reaction solution is cooled to room temperature, and the generated salt is quickly filtered to obtain a benzene solution of methylene triphenylphosphorane. As described in detail above, the present invention is a method for producing dihydrotagetone from y-ketoaldehyde using metaacrolene diethyl acetal, which is easily obtained from methachlorene, as a raw material, and the process is short and This is an industrially advantageous method because it does not use oxidation reactions or Grignard reactions unlike conventional production methods.

[Brief explanation of drawings]

The figure is a diagram showing the relationship between the reaction time and the yield of y-ketoaldehyde acetal in the reaction of metaacrolene diethyl acetal and 3-methylputanal.

Claims (1)

[Claims] 1 Produce γ-ketoaldehyde acetal by a radical addition reaction between meta-acrolene diethyl acetal and 3-methylbutanal, hydrolyze this γ-ketoaldehyde acetal to produce γ-ketoaldehyde, and then convert this γ-ketoaldehyde into γ-ketoaldehyde. 1. A method for producing dihydrotagetone using metaacrolene acetal as a raw material, characterized in that dihydrotagetone is produced by a Witteich reaction between the compound and methylenetriphenylphosphorane.