JPS62207238A - Production of beta-alkoxyacrolein derivative - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a synthetic intermediate for photosensitive dyestuffs, etc., used for silver salt photography with high operating efficiency in one step, by reacting a readily available alkyl vinyl ether as a starting raw material with a Vilsmeier reagent. CONSTITUTION:A Vilsmeier reagent prepared from a disubstituted formamide and POCl3, etc., and expressed by formula II (R<2> and R<3> are alkyl or aryl; X<-> is anion, e.g. Cl or PO2Cl2) is reacted with an alkyl vinyl ether, readily obtained by dealcoholization of the corresponding acetal and expressed by formula I (R is H, halogen, alkyl, alkoxy, aryl or heterocyclic residue; R<1> is lower alkyl) in the presence of an alkali, e.g. K2CO3, etc., at -20 deg.C- the boiling point of a solvent used and the resultant reaction product is hydrolyzed to afford the aimed compound expressed by formula III. EFFECT:Since the reaction can be readily controlled and can be increased, this method is industrially advantageous.

Description

Detailed Description of the Invention (A> Industrial Applications β-Alkoxyacrolein, which is an enol ether of malonaldehyde, and its derivatives are useful as C3 units in organic synthesis. Particularly in the field of photography, silver salt photography It is an important compound as a synthetic intermediate for sensitizing dyes and filter dyes used in

The present invention relates to a novel method for synthesizing β-alkoxyacrolein derivatives.

(B) Prior art and its problems However, there are many problems with the conventionally known synthesis methods for β-alkoxyacroleins, and there are almost no methods that can be used on an industrial scale.

For example, Chemical Abstracts 5817826a (1
In the method of 964), malonaldehyde tetraethyl acetal is hydrolyzed under acidic conditions, converted to sodium salt with Na011, and then reacted with methyl chlorocarbonate to obtain β-methoxycarbonyloxyacrolein, which is then decarboxylated under acidic conditions. Then, β-methoxyacrolein is obtained.

Also, Chemical Abstracts Volume 58, 9070b (
'1964) and Chemical Abs 1 to Lacto 64 volumes,
3397d ('1966) is a generalization of the above method. That is, using malonaldehyde tetraethyl acetal having a substituent as a starting material, a β-alkoxyacrolein derivative is obtained by hydrolysis, carbalkoxylation, and decarboxylation in the same manner as in the above-mentioned route. This method requires a long process and is difficult to obtain the substituted malonaldehyde acetal as a starting material, and it is also difficult to control the conditions in the decarboxylation reaction, requiring a long reaction time, making it unsuitable for industrial use. Furthermore, Chemical Abstracts 51e13761 (1957) describes a method of using a β-dimethylaminoacrolein derivative as a starting material instead of malonaldehyde tetraethyl acetal and obtaining malonaldehyde by hydrolysis thereof.

This method is superior to the above-mentioned methods in that raw materials are easily available. Although this method solves the first problem of the above-mentioned route, it cannot be used as an industrial method unless the subsequent steps of carboalkoxylation and decarboxylation are improved, so it is necessary to develop a new synthetic route. It became.

(C) Purpose of the Invention The purpose of the present invention is to provide a novel method for synthesizing β-alkoxyacrolein derivatives that can be used industrially.

(D> Structure of the invention This objective was achieved by the following method.

That is, by reacting the alkyl vinyl ether derivative represented by the general formula (I> with (71) vr Ismeier reagent and hydrolyzing it under alkaline conditions,
The desired β-alkoxyacrolein derivative (III) was obtained in one step.

(In the formula, R1 represents a lower alkyl group. R2 and R3 may be the same or different and represent an alkyl group and an aryl group, respectively. Also, R is a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, Indicates an aryl group or a heterocyclic residue. Also, X- is an anion, a chlorine atom, PO2Cj
! Indicates z. ) The alkyl vinyl ethers (I), which are the starting materials for the production method of the present invention, can be easily synthesized by dealcoholization of the corresponding acetal according to a conventional method. Also, the vr Ismcier reagent does not need to be isolated during the reaction, but is prepared from the corresponding disubstituted formamide and phosphorus oxychloride or from the disubstituted formamide and phosgene when opened in the reaction system. In addition, the ratio of the starting materials (I> and (I[I)) used is
The molar ratio is 1:0.5 to 5, and the solvent is a disubstituted formamide (e.g., dimethylformamide, N-methylformanilide, etc.), a halogenated hydrocarbon (e.g., chloroform, methylene chloride, tetrachloroethane, etc.) is preferable, and the mother used is 1:0.5 to (I) by weight.
It is 50. The reaction temperature is from -20°C to the boiling point of the solvent used.

Also, during hydrolysis, the alkali used is alkali carbonate,
Caustic alkali is preferred and treatment at low temperatures is preferred.

Detailed reaction conditions will be described below using specific examples.

(E) Examples Synthesis Example 1> Synthesis of α,β-jethoxyacrolein.

Phosphorous oxychloride 41.1 is added dropwise to DMF 60 over 30 minutes at room temperature. After stirring at room temperature for 30 minutes, 17.3 g of 1,2-jethoxyethylene was added while cooling the outside with ice-water.
was added dropwise over 30 minutes. 30 minutes at room temperature, roughly 80℃
After heating for 30 minutes and allowing to cool, the reaction mixture was slowly poured into 500 d of ice water, and potassium carbonate was added to make it pl-1s. The mixture was stirred roughly for 30 minutes at room temperature. Water was added to the reaction mixture, salted out with common salt, and extracted four times with 80ml of ether.

After washing the ether layer with water and drying with anhydrous magnesium sulfate,
The ether was slowly distilled off at normal pressure, and the residue was distilled under reduced pressure.

Yield 8.4g bp108-114°C/3mm
flgnmr(CDCfs) δ, 9.1
4 (1 to 1.5-CHO) 6.83 (1H,S,
β -CH) 4.2 8 (2 to 1
,? J=8Hz, -0-C±izC
H3) 4.18 (21-(,y J=8
1-1z, -0-CH2-Ct-13> 1.4
4 (31-1, t 1 J=8 g12.
-OCHz3) 1.32 (31-1,
t, J=8Hz, -0CHz Cl-13> Synthesis Example 2> Synthesis of β-ethoxyacrolein.

2M (0.3 mol) of phosphorus oxychloride was added dropwise to 50ml of DMF at room temperature, and after stirring at room temperature for 30 minutes, 7.2 g (0.1 mol) of ethyl vinyl ether was added dropwise to the solution while cooling the outside with ice-water. do. 15 minutes at room temperature, then 30 minutes at 80°C
After reacting for several minutes and cooling, the reaction mixture was poured into ice-water, and sodium carbonate was added to adjust the pH to 8, followed by stirring at room temperature for 1 hour.

The reaction mixture was diluted with water, salted out with common salt, extracted with ether, the ether layer was washed with water, dried over anhydrous magnesium sulfate, and then distilled off at normal pressure, and the residue was distilled under reduced pressure.

Yield M16.3g bp56-62℃15mlffnm
r(CDCe3) δ, 9.36 (1H, d, J=
8Hz, -CHO) 7.40 (1
t1, dl, ) = 12H2, β-CH> 5.6
2 (11-1, d, d, J=12H7, a-CH)
4.06 (2H,'?J=71-1z, OCH
2CH3) 1.40 (3H, t, J=7
1z, OCH2CH3) (F) Effects of the invention and above) 7f, As mentioned above, the production method of the present invention has advantages such as easy availability of starting materials, short reaction steps, and high work efficiency. have. In general, since the reaction is easy to control, it can be scaled up and is an effective method that can be used industrially.

Claims (1)

[Claims] A method for producing a β-alkoxyacrolein derivative, which comprises reacting an alkyl vinyl ether with a Vilsmeier reagent.