DE2225612A1 - METHYL-FUMARDIALDEHYDE MONOACETALS AND METHOD FOR THEIR PRODUCTION - Google Patents

Description

Badische Anilin ·· & Soda -Fabrik AO

Our symbols: O „Ζ. 29 178 Rr / Fe 6700 Ludwigshafen, May 24th 1972

Methyl-fumaric dialdehyde monoacetals and processes for their Manufacturing

The invention relates to methyl-fumaric dialdehyde monoacetals of the formula I.

R ^ -O _x - ^ s
u / CH - C = C - C ^ (I)

R-O '12 Il ^ O

rl H

1 2
in which R and R are different and either a hydrogen

■ ά h. atom or a methyl group, Br and R are identical or different and each have an aliphatic hydrocarbon

3 4 radicals with 1 to 4 carbon atoms or Br and R together denote an ethylene radical or a propylene radical, which can be substituted by alkyl groups with 1 to 4 carbon atoms, preferably methyl groups.

The new compounds are of exceptional interest as intermediates in the synthesis of carotenoids. For example can be achieved by reacting 3-methyl-fumaric dialdehyde-1-acetalen with the ylid of ß-Jonylidenäthyltriphenylphosphoniumsalzen and subsequent hydrolysis in a simple manner the coveted and so far only in a complex manner to produce Produce retinal, which also enables an economical synthesis of ß-carotene »Furthermore can For example, retinyl triphenylphosphonium salt produced from retinol or vitamin A acetate by WITTIG olefination with 2-methyl-fumaric dialdehyde-1-acetals and then Hydrolysis elegantly converted into the ß-apo-Cgc-carotinal will.

The new methyl-fumaric dialdehyde monoacetals can be, for example prepare by the methyl derivatives of the corresponding but-2-en-4-ol-l-al-acetal of the formula II

R ^ - 0
u ^ CH - C = C - CH ₉ - OH (II)

^R - ° I2 I'1

675/71 + R R _

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in which R to R have the meaning given above, with a pyridine-sulfur trioxide complex in dimethyl sulfoxide and in Presence of triethylamine or a pyridine-chromium trioxide complex oxidized in pyridine or with manganese dioxide or nickel dioxide in an inert solvent.

The methyl derivatives of but-2-en-4-ol-1-al-acetals required as starting materials of formula II can, for example, in a simple manner by acetalizing ß-formylcrotyl acetate or 3-methyl-4-acetoxy-crotonaldehyde by customary methods and subsequent reaction of the acetals obtained with a methanolic solution of sodium methylate can be prepared.

Preferred compounds of the formula II that may be mentioned are:

""^> ^ k / ^{0H and} "" ^X CH ₃ O

2 ^w "'2

For the oxidation of the compounds of the formula II with a pyridine-sulfur trioxide complex in dimethyl sulfoxide as a solvent and in the presence of triethylamine is generally the solution of the pyridine-sulfur trioxide complex in dimethyl sulfoxide at about 25 C slowly to a mixture of the Compound of formula II to be oxidized, dimethyl sulfoxide and triethylamine added, the end of the reaction by gas chromatography determined and the reaction mixture in the usual way, for example by adding approximately the same amount Water and subsequent benzene extraction worked up.

The pyridine-sulfur trioxide complex is obtained, for example, by slowly adding dropwise pyridine to a cooled and stirred mixture of sulfur trioxide and carbon tetrachloride and removing traces of pyridinium sulfate from the collected Product by washing with ice water »Pyridine and sulfur trioxide are used in approximately equimolar amounts, Carbon tetrachloride in about 4 times the amount by weight of the sulfur trioxide.

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This complex can also be converted into chlorosulfonic acid with twice the molar amount of pyridine and washing out the pyridine hydrochloride formed with ice water.

The pyridine-sulfur trioxide complex is generally used in this oxidation in about J to 4 times the molar, the triethylamine in 5 to 28 times the molar amount, based on the alcohol to be oxidized. The dimethyl sulfoxide as a rule, it is used in a multiple excess; it serves at the same time as a solvent »

According to this oxidation process, the methylfumaric dialdehyde monoacetals of the formula I can be obtained in yields of up to 70 % of theory. However, the pyridine-sulfur trioxide complex must be prepared separately before the reaction.

For the oxidation of compounds of the formula II with a chromium trioxide-pyridine complex one generally works as follows:

By gradually adding chromium trioxide to intensely stirred anhydrous pyridine cooled by an ice bath a suspension of the pyridine-chromium trioxide complex in pyridine is prepared. One adds one to this suspension Solution of the alcohol to be oxidized in pyridine, the mixture obtained is stirred intensively for about 30 minutes and left then stand at room temperature for about 15 to 22 hours. For working up, the reaction mixture is poured into water and extracted several times with ether. This procedure uses about 3 moles of the pyridine-chromium trioxide complex per mole alcohol to be oxidized. The reaction is generally carried out at room temperature.

But you can also use the chromium trioxide-pyridine complex as a methylene chloride solution manufacture and use. For this purpose, dry chromium trioxide is added in portions to a cooled one Solution of anhydrous pyridine in methylene chloride, stir the whole thing for another 10 to 20 minutes and then gradually drip the alcohol to be oxidized to this solution. The reaction mixture is worked up by decanting off the methylene chloride solution from that formed in the reaction

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black residue, extracting the residue with ether, Washing of the combined organic phases with dilute aqueous sodium hydroxide solution, dilute hydrochloric acid, sodium bicarbonate solution and finally, saturated saline.

This process variant is generally used an approximately 0.8 to 1.4 molar solution of pyridine in methylene chloride and 1/2 mole of chromium trioxide per mole of pyridine.

The disadvantage of this process is that in the variant first described, the preparation of the oxidizing reagent is not carried out is completely harmless, since the chromium trioxide-pyridine mixture burns easily - and that with the last-mentioned variant pro Moles of alcohol to be oxidized up to 6 moles of chromium trioxide must be used.

For the oxidation of compounds of formula II with activated manganese dioxide or nickel peroxide in an inert solvent is advantageously added to the alcohol to be oxidized slowly at temperatures of about 20 to 100 ⁰ C to a stirred mixture of activated manganese dioxide or nickel in the desired solvent and the reaction mixture left to react with stirring. The reaction mixture is worked up by filtration and concentration. In general, about 1.5 to 10 moles of the oxidizing agent are used per mole of alcohol to be oxidized. The amount of nickel peroxide to be used depends, however, on its oxidation activity, ie on the content of nickel peroxide in addition to nickel oxide.

Suitable inert solvents are especially saturated aliphatic hydrocarbons such as petroleum ether and cyclohexane, and aromatic hydrocarbons such as benzene or toluene ^ or in the case of manganese dioxide, halogenated hydrocarbons, vie carbon tetrachloride. Chloroform and dichloroethylene into consideration.

The yields of methylfumaric dialdehyde monoacetals also depend strongly on the activity of the manganese dioxide and nickel dioxide used. Furthermore, the filtration of the metal

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oxides from the reaction mixture certain difficulties.

As a further improvement it has now been found that methyl

1 2 fumaric dialdehyde monoacetals of the formula I in which R and R are different and either represent a hydrogen atom or a methyl group and Yr and R together represent a propylene radical which can be substituted by alkyl groups with 1 to 4 carbon atoms, preferably methyl groups, can be prepared quickly and easily and with very good yields if the methyl derivatives of the corresponding but-2-en-4-ol-1-al-acetal of the formula II are oxidized with chromic acid in sulfuric acid solution.

This fact is extremely surprising since α, ß-unsaturated Acetals generally hydrolyze very quickly in acidic solution. Accordingly, an analog one succeeds Oxidation with chromic acid in sulfuric acid solution when used of dimethyl or ethylene glycol acetals of the corresponding but-2-en-4-ol-l-ale as starting materials are not. as Compounds of the formula II which can be oxidized in this elegant way to methyl-fumaric dialdehyde monoacetals are said to be named for example:

2-methyl-but-2-en-4-ol-l-al (l '.J'-propylene) acetal, 2-methyl-but-2-en-4-ol-l-al (2 ^f .4 "-pentylene) acetal, 2-methyl-but-2-en-4-ol-1-al- (2'.2'-dimethyl-propylene) -acetal, 3-methyl-but-2-en-4 -ol-l-al- (l '.J5'-propylene) -acetal and 5-methyl-but-2-en-4-ol-l-al- (2'.2'-dimethyl-propylene) -acetal .

Oxidation of the methyl derivatives of but-2Ten-4-ol-l-al-monoacetals with 1,2-doles by chromic acid in sulfuric acid Solution is generally carried out as follows:

The alcohol to be oxidized is dissolved in acetone and the sulfuric acid chromic acid solution is added ^{to this solution at temperatures from -15 to + JO 0} C, preferably -5 to +20 ^{0 C.}

The acetone is generally used in such amounts that the alcohol to be oxidized is about 0.1 to 0.8, preferably 0.2 to 0.4 molar solution is present. Other solvents which are inert under the reaction conditions can also be used use, but the reaction then generally proceeds

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slower and not completely. If, for example, benzene is used as the solvent, about 10% of the starting material is still recovered unchanged even with a reaction time of 2 to J3 hours and use of a 50% excess of the oxidizing agent.

A reagent according to Jones, for example, which is about 8 normal in chromic acid and sulfuric acid and which is used in equivalent amounts, is used as the sulfuric acid chromic acid solution. But you can also work with an excess, for example up to 50 % , of chromic and sulfuric acid. It is advantageous to use an excess of 10 to 20 % of a 4 to 8 normal solution of chromic acid and sulfuric acid.

The reaction mixture is worked up in a customary manner by pouring the reaction mixture into approximately the equal amount of water, extraction with a solvent that is practically immiscible with water and distillation.

It has also been found that methyl fumar dialdehyde

1 2 monoacetals of the formula I, in which R and R are different and either a hydrogen atom or a methyl group

"5 4
and Br and R are identical or different and each represent an aliphatic hydrocarbon radical having 1 to 4 carbon atoms or a phenyl radical, can advantageously be prepared if a 4-alkoxy- (phenoxy) -methyl-crotonaldehyde of the formula III

, / Η

R - ^ - O- CH ₀ -C = CC (IH) ,

'2' 1 '^ O R ^ R ^{x υ}

in the R to Er have the meaning given above Heating with excess acetic anhydride and an alkali acetate, carbonate or hydroxide or a non-aromatic bicyclic amine in a butadiene diol derivative Formula IV

R ^ - 0 - CH = C - C = CH - 0 - CO - CH, (IV) '2 ¹ I ^

in which R to Rr have the meaning given above,

leads, and this initially at temperatures from -70 to +10 ⁰ C,

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preferably -60 to 0 ⁰ C with chlorine or bromine in a solvent inert under the reaction conditions and then at temperatures of -20 ⁰ C to +10 ⁰ C with a strong base and an ■ alcohol with 1 to 4 carbon atoms and / or Converts phenols.

The 4-alkoxymethyl-croton-aldehydes required as starting materials for this process of formula III can, for example, be prepared in a simple manner in the following way:

0 = CH - C = CH - CHo - Cl

ι egg

HC (O alkyl,) · H ^fl

Alkyl CL

j, CH-C = CH-CH ₀ -Cl
Alkyl O ^ ' ^Λ

Alkyl
Alkyl

After ,, CH, 0H
j 3

CH - C = GH - CH ₀ - OCH ₁ .

yJOJO +

0 = CH - C = CH - CH ₀ - OCH ^

ι e- J

Suitable starting materials are selenium, for example

1-al, 2-methyl-4-isopropoX3r-bmt-2-en-l-al _s aM oxy-but-2-en-l-al, ^ -Methyl - ^ - methoxy-but-S-en-l -al and 5-methyl-4-ethoxy-but-2-ea-l-al.

Heated for the transfer of 4-alkoxy-methyl-eroton-aldehydes of the formula III in the Butadiendiolderivate the Forßiel ΤΨ "If these generally with stirring under reflux with an excess of acetic anhydride and an alkali metal acetate, carbonate 'or hydroxide or einQßä foicyeiisehen AMIA to simmer.

Öas acetic anhydride is used here in amounts of

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3 to 7 moles, preferably 4 to 6 moles per mole of starting compound.

Sodium and potassium acetate, as well as potassium carbonate and potassium hydroxide, are preferred as effective alkali compounds. The alkali acetates, carbonates and hydroxides are generally used in amounts of 1 to 3 moles per mole of output connection.

When using sodium acetate, the reaction time is for this reaction step about 7 to 9 hours, while using potassium acetate, potassium carbonate and potassium hydroxide for the same degree of conversion is only about 1 to 2 hours, preferably 40 to 80 minutes.

Non-aromatic bicyclic amines, for example, 1,4-diazobicyclo / ~ 2.2.2_J7-octane (DABCO) or 1,5-diaza-bicyclo / ~ 4.5.0_7-nonen- (5) into consideration.

The usual amines such as ethylamine, triethylamine, pyridine and quinoline, on the other hand, cannot be used for this reaction will. The non-aromatic bicyclic amines are generally used in amounts of preferably 1 to 2 mol per Mole of starting compound.

The reaction mixture is worked up in the usual way Way, for example by stirring with a water-immiscible solvent, preferably diethyl ether or Benzene, removal of the alkali acetate by filtering off or by washing the mixture with water and then fractionating Distillation of the organic phase. The butadiene diol derivatives of Formula IV are in the form of cis-trans isomers received and fed to the further implementation. These compounds or isomer mixtures are not yet available described. Physical data of them are given in Examples 6-11.

The butadiene diol derivative obtained is dissolved for further reaction of the formula IV initially in a solvent which is relatively inert under the reaction conditions, the solution is added

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with stirring, intensive cooling, and exclusion of oxygen and moisture, gradually mixed with chlorine or bromine, then added the reaction mixture with an alcohol and / or phenol and a strong base and leaves the whole thing 1 to 2 hours React stirring at room temperature. As · under the reaction conditions Inert solvents are especially saturated hydrocarbons, such as n-pentane, cyclohexane, halogenated ones Hydrocarbons such as methylene chloride, carbon tetrachloride, and ethers such as diethyl ether, dimethyl ether and Tetrahydrofuran into consideration.

Chlorine or bromine are advantageously added to the reaction mixture in the form of concentrated solutions in carbon tetrachloride. the The halogens can be added as quickly as the heat of reaction can be dissipated. The halogens used one in amounts of about 1 mole to 1.1 moles of halogen per mole of butadiene diol derivative.

Finally, an alcohol or phenol is added to the reaction mixture. The alcohol is used in amounts of 5 to 20 moles, preferably 10 moles per mole of butadiene diol derivative.

Suitable strong bases are alkali metal alcoholates, alkaline earth metal alcoholates or alkali metal phenolates. Used with particular advantage one sodium or potassium alcoholates, in particular that alcoholate of the alcohol with which the reaction mixture is moved. The strong bases are generally used in amounts of 2 to 5 mol, preferably about 2.5 mol per mole of butadiene diol derivative of formula IV.

The reaction mixture is worked up in a customary manner, for example by adding the reaction mixture with water and a solvent that is practically immiscible with water, such as chloroform, benzene or petroleum ether, and Fractionating the separated organic phase.

With the help of the processes described, it was possible for the first time to use them as intermediates for the synthesis of carotenoids extremely interesting new methyl-fumaric dialdehyde monoacetals

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of the formula I. The procedures are relatively straightforward Way to realize and proceed in general with quite good yields.

example 1

(Preparation of the starting compounds)

a) Acetalization of ß-formyl crotyl acetate.

A mixture of 142 g of β-formylcrotyl acetate, 107 g of neopentyl glycol, 0.2 g of p-toluenesulfonic acid and 500 ml of benzene is allowed to boil for 3 hours under reflux and with water removed. The cooled reaction mixture is washed with NaHCO ^ solution and dried _{over Na 2} SO _2. There are 216 g of 2-methyl-4-acetoxy-but-2-en-l-al-l- (2 '.2'-dimethylpropylene) acetal _n of boiling point Kp obtained = 95 ⁰ C.

b) reaction with methanolic sodium methylate

A mixture of 228 g of 2-methyl-4-acetoxy-but-2-en-l-all- (2 '^' - dimethyl-propylenj-acetal, 5 ml of a 30% strength by weight methanolic sodium methylate solution and 250 ml of methanol is heated at 450 torr and a bath temperature of 60 ^° C., during which the methanol is distilled off. 150 ml of methanol are then added again and this is distilled off. The residue is taken up in methylene chloride, washed with water and concentrated. 172 g of 2-methylbut are obtained -2-en-4-ol-l-al- (2'.2'-dimethyl-propylene) -acetal of boiling point Kp ₀ ^ = 106 to 110 ⁰ C,

Example 2

(Oxidation of methyl-but-2-en-4-ol-l-al-acetals with chromic acid in sulfuric acid solution)

To a solution of 37.2 g (0.2 mol) of 2-methyl-but-2-en-4-oll-al- (2'.2'-dimethyl-propylene) acetal in 1 liter of acetone is added at + 5 ^° C. a mixture of 15 * 2 g of chromium trioxide and 23 g of concentrated sulfuric acid, which was made up to 100 ml with water, was added all at once. The reaction mixture is then poured into 1 liter (cold) water and extracted 3 times with 150 ml of benzene and the benzene phases are washed with 5 % sodium bicarbonate solution. When the combined benzene extracts are worked up by distillation, 31.8 g of 2-methyl-fumaric dialdehyde-l ~ (2'.2'-dimethyl-propylene) acetal are obtained.

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The yield is accordingly 85 % of theory.

Kp _{0 ±} = 82 to 85 ⁰ C..

NMR ((T / ~ PPm_7 CDCl ₃ , TMS):

10.10 (d, IH) - 6.10 (m, IH); 4.80 (S, IH); 3/58 (m, ■ 4h); 2.18 (S, 3H); 1.21 (S, 5H) - 0.75 (S,

In the same way, by reacting 0.2 mol of the corresponding methyl-butr-2-en-4-ol-l-al-acetals, the methyl-fumaric dialdehyde monoacetals mentioned and characterized below are obtained in the given yield: 2-methyl- fumaric dialdehyde-l- (l'.3'-propylene) -acetal bp _{0 χ} = 80 ⁰ Cj yield 78 % of theory. NMR (cf / ~ ppm_7, CDCl ₅ , TMS):

10.08 (d, 1H); 6.12 (d, 1H); 4.93 (S, IH); 4.00 (m, 4H); 2.18 (S, 3H) j 2.0-1.2- (m, 2H).

2-methyl-fumardialdehyd-l- (2 ^T .4'-pentylene) -acetal: Kp = _{0 2} 70 to 72 ⁰ C; Yield 75 % of theory.

NMR ((T / "" ppm_7, CDCl ₃ , TMS):

ΐσ; Ό8 (d, IH); 6.17 (m, 1H); 4.95 (S, IH); 4.1-3.6 (m, 2H); 2.18 (m. 3H); 1.6-1.2 (m, 2H); 1.24 (d, 6h).

3-methyl-fumaric dialdehyde-1- (2 ', 2'-dimethyl-propylene) -acetal bp _{0 2} = 85 to 87 ° C; 78 % of theory ^ NMR ((T / ~ ppm_7, CDCl ₃ ; TMS):

9.47 (S, IH); 6.35 (m, 1H); 5.30 (d, 1H); 3.60 (m, 4H); 1.82 (d. 3H); 1.24 (S, 3H); 0.77 (S,

Example 3

(Oxidation with a pyridine-chromium trioxide complex). 18Ο g of CrO- are added in portions to 285 g of pyridine in 2.5 liters of methylene chloride at up to 20 ° C. and the mixture is stirred for 15 minutes. 69 g of 2-methyl-but-2-en-4-ol-1-al- (2'.2'-dimethyl-propylene) -acetal are added dropwise to this reaction mixture in the course of 30 minutes. The methylene chloride solution is then decanted off, the black residue formed during the reaction is washed twice with methylene dichloride and the combined organic phases are washed one after the other with 1 1 5% NaOH, 5% HCl, 5% NaHCO ₃ and saturated NaCl. Solution washed.

. -12-

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Working up the organic phase by distillation gives 36.5 g of 2-methyl-fumaric dialdehyde-1- (2'.2'-dimethyl-propylene) acetal. The yield is 53 % of theory.

Example 4

(Oxidation with a pyridine-sulfur trioxide complex in dimethyl sulfoxide (DMSO) and in the presence of triethylamine) To a mixture of 18.6 g of 2-methyl-but-2-en-4 ~ ol-1-al- (2 ^f . 2 ^! -Dimethyl-propylene) acetal, 50 g of triethylamine and 150 ml of DMSO (dried over a molecular sieve of 4 Å) are added dropwise 48 g of pyridine-sulfur trioxide complex in 200 ml of DMSO and the reaction mixture for 30 minutes stirred. It is then acidified to pH 6 with 10 # H _{2 SO ^.} After the reaction mixture has been replaced with approximately the same amount of water, it is extracted with benzene. When the organic phase is worked up by distillation, 13 * 8 g of 2-methyl-fumaric dialdehyde-1- (2'.2 ^} -dimethyl-propylene) -acetal are obtained. The yield is 75 % of theory.

The pyridine-sulfur trioxide complex is made by combining of chlorosulfonic acid with twice the molar amount of pyridine at 5 ⁰ C temperature and washing with ice water for the separation of pyridine hydrochloride.

Example 5

18.6 g of 2-methyl-but-2-en-4-ol-l-al (2.2 * -dimethylpropylene) acetal, 50 g of manganese dioxide (prepared according to Attenburrow) and 400 ml of benzene are heated to the boil for 3 hours. After filtering off and concentrating, 14.5 g (79 % of theory ) of 2-methylfumaric dialdehyde-1- (2'.2'-dimethylpropylene) acetal are obtained.

Example 6

a) A mixture of 114 g (1 mol) of 2- ^M ethyl-4-methoxy-but-2-en-1-al (4-methoxy-tiglic aldehyde), 500 g of acetic anhydride and 196 g (2 mol) of anhydrous potassium acetate is heated with stirring and RückflußkUhlung in a 2 L flask 50 minutes to about 135 ⁰ C. After the reaction mixture has cooled to room temperature, it is stirred with 700 ml of diethyl ether and the potassium acetate which has precipitated is filtered off with suction.

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The piltrate is fractionated on a 20 cm long Vigreux column. The fraction with a boiling point of Kp _{n K} = 50 to 65 C consists of a mixture of the cis-trans isomers of 1-acetoxy-2-methyl-4-methoxy-buta-1,3-diene. The yield is 70 % of theory .

NMR (<TZ ~ PP ^m _7 'CDCl ,, TMS)

C = C 3 H. - OCH, Hz) AdO - 7.07 -C = C Hz) C ₁ -H 6.55 (S, IH) C ₄ -H 5.48 (d, IH, J'Pi'Q 13 C-H 3.58 (d, IH, H ί ¹ ^ q,, pn. ) C = C 3 H. - OCH, Ä. <S0 - -C = C 6.81 H C ₁ -H (S, IH)

5.92 (d, IH, J _m : 13 Hz)
6.60 (d, IH, J ^ 13'Hz)
3.63 (S,

b) If you work as described in Example 6a, but instead of 196 g of potassium acetate, 164 g (2 mol) of anhydrous sodium acetate are used and the reaction mixture is heated to about 135 ^° C. for 8 hours instead of 50 minutes, 107 g of a cis- trans isomer mixture of 1-acetoxy-2-methyl-4-methoxy-buta-1,3-diene _0. The yield is 68 % of theory.

Example 7

If the procedure is as described in Example 6a, but instead of 114 g of 2-methyl-4-methoxy-but-2-en-1-al, 128 g (1 mol) of 2-methyl-4-ethoxy-2-butene are used -Iral (4-ethoxy-tiglic aldehyde), 126 g of a distillate with a boiling point of Bp ₀ g = 53 to 69 ⁰ C are obtained, which, according to gas chromatographic and NMR spectroscopic analysis, consists of 2 cis-trans isomers of 1-acetoxy-2 -methyl-4-ethoxy-buta-1,3-diene. The yield is 74 % of theory.

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Example 8

A mixture of 114 g of 2-methyl-4-methoxy-but-2-en-l-al, 500 g of acetic anhydride and 112 g (1 mol) of 1,4-diaza-bicyclo / ~ 2.2.2_7-octane (DABGO) is heated for 1 hour at about 135 ⁰ C with stirring and RUckflußkühlung in a 2 L-Kölben. After the reaction mixture has cooled to room temperature, it is mixed with 600 ml of benzene and washed 3 times with 500 ml of water each time. When the organic phase is fractionated, 101 g of a fraction with the boiling point Kp _{n κ} = are obtained

O ^u i 0

up to 65 ° C., which, according to gas chromatographic and NMR spectroscopic analysis, consists of a mixture of 3 cis-trans isomers of 1-acetoxy-2-methyl-4-methoxy-buta-1,3-diene. The yield is 62 %.

Example 9

A mixture of 71 g (0.5 mol) of 2-methyl-4-isopropoxy-but-2-en-1-al, 250 g of acetic anhydride and 98 g (1 mol) of anhydrous potassium acefate is stirred and refluxed for 45 minutes to approx . 135 ⁰ C heated. After cooling the reaction mixture, stirring with 350 ml of diethyl ether, suction of potassium acetate and fractionation of the filtrate is 136 g of a fraction having a boiling point Kp _Q u = 55 to 56 ⁰ C obtained from l-acetoxy ~ 2-methyl-4-isopropoxy -buta-l, 3-dlen consists.
The yield is 74 % of theory.

Example 10

A mixture of 176 g (1 mol) of 2-methyl-4-phenoxy-but-2-en-lal, 500 g of acetic anhydride and 196 g (2 mol) of anhydrous potassium acetate is brought to approx . 135 ⁰ C heated. After the reaction mixture has cooled, it is mixed with 600 ml of benzene, the precipitated potassium acetate is filtered off and the filtrate is fractionated. Obtained I86 g of a fraction having the boiling point Kp _n - is ⁰ to 112 C, consisting of l-acetoxy-2-methyl-4-phenoxy-buta-l, 3-dien = IO8.
The yield is 85 % of theory.

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A mixture of 11.4 g (1 mol) 3-methyl-4-methox3r-but-2-en-1-al, g acetic anhydride and 207 g (1.5 mol) anhydrous potassium carbonate is heated to approx. the cooled reaction mixture is stirred with 700 ml of ether, the precipitated Xaliumsalsa is suctioned off * the piltrate is concentrated in a rotary evaporator and the residue is fractionated. This gives 106 g of a fraction having a boiling point Kp = ₀ ^ 48 to 55 ⁰ C, which consists of a mixture of ois-trans-isomers of l ~ Acetoxy-3-methyl ~ 4 ~ fflethoxy-buta - l. ₁ 3 " ^o dien. Exists ¹ .
The yield is 65 % of theory.

Example 12

a) A solution of 31.2 g (0.2 mol) of 1-aceto3ty-2-methyl-4-methoxy-buta-1, 3-diene in 150 ml of ether is added with stirring, ice cooling, nitrogen gassing and Feuohtigkeitsauaschluß 10.7 ml (0.21 mol) of bromine were added dropwise. Man

- makes sure that the temperature of the reaction mixture does not exceed ^{5 0 C »}

The reaction mixture is then mixed with one Solution of 27 g (0.5 mol) Mrtriuntaefchylafc in 40Ö BiI methanol and stir the. Mixture 1 bp at R & imtemperature. The reacted mixture is concentrated to 2/3 of the volume, 500 ml of water are added - and a total of 600 ml of chloroform extracted. From the separated organic Phfe.se are after the solvents have been distilled off in a rotary evaporator by high vacuum fractionation, 18.4 g of 5-methyl-fumaric dialdehyde-1-dimethylacetal obtain.

The yield is 64 % of theory, based on 1-acetoxy-2-methyl-4-methoxy-buta-1,3-diene. Kp ₁₀ = 71 to 76 ⁰ C.

b) When the procedure is as described under a), but instead of 150 ml of ether I50 ml of n-pentane and instead of ice-cooling, brine cooling * which ensures a maximum increase in the temperature of the reaction mixture to -20 ⁰ C, one obtains 20.6 g 3-methyl-fumaric dialdehyde-l-dimethyl-

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acetal with a boiling point of Kp _{Q 2} = 40 to 60 ° C. The yield is 71 % of theory.

c) When the procedure is as described under a), but using, instead of the bromination be.1 ice cooling a cooling bath to cool the reaction mixture during the addition of bromine to -60 ⁰ C, we obtain 20.2 g of 3-methyl-fumardialdehyd-ldimethylacetal .
The yield is 70 % of theory.

Example 13

A solution of 17 g (0.1 mol) of l-acetoxy - ^ - methyl - ^ - äthoxybuta-l, 3-diene in 80 ml of n-pentane is added dropwise with 5 ^{at -60 0 C with stirring, nitrogen gassing and exclusion of humidity} * 1 ml of bromine (0.1 mol) in 5.1 ml of carbon tetrachloride was added. The cold bath is then removed and when the temperature of the "reaction mixture has ^{risen to -20 0} C, this is mixed with a solution of 17 g (0.25 mol) of sodium ethylate in 200 ml of ethanol and the whole thing is stirred for 1 hour at room temperature fully reacted mixture is mixed with 300 ml of water and extracted 3 times with a total of 300 ml of ether. from the separated organic phase is 9 * 8 g 3-methyl-l-fumardialdehyd-diethylacetal isolated from the boiling point Kp _no = 40 to 63 ⁰ C.
The yield is 59 % of theory.

309851/1117

Claims (10)

-if- ^ O.Z. 29 I78 Methyl fumaric dialdehyde monoacetals of the formula I R ^ C \ TT - υ ^ ^Ά u CH -C = C-Cj. (I), ■ R ^ - O ^ '2' 1 ^ O 1 2
in which R and R are different and either a water ■ 5 h is a material atom or a methyl group, R and R are identical or different and each represent an aliphatic hydrocarbon radical with 1 to 4 carbon atoms or Br and R together represent an ethylene radical or a propylene radical with alkyl groups with 1 to 4 C. Atoms, preferably methyl groups, can be substituted. ' 2. 2-methyl-fumaric dialdehyde-1- (l'.3'-propylene) acetal. 3. 2-methyl-fumaric dialdehyde-1- (2'.4'-pentylene) acetal. 4. 2-methyl-fumaric dialdehyde-1- (2'.2'-dimethylpropylene) acetal. 5. j5-methyl-fumaric dialdehyde-1- (2 '.2 * -dimethylpropylene) acetal. 6. 2-methyl-fumaric dialdehyde-1-dimethyl acetal. 7 · 3-methyl-fumaric dialdehyde-1-dirnethylacetal. 8. Process for the preparation of methyl-fumaric dialdehyde mono-. acetals of the formula I R ⁵ - O _x .H u , .CH - C = C - C (I) R ^ - 0 &quot; 2 '1 &quot; ^ O χι Γι 1 2 in which R and R are different and either denote Nasser's 4 atomic atom or a methyl group, Br and R are identical or different and each denote an aliphatic hydrocarbon radical having 1 to 4 carbon atoms or Br and R together denote an ethylene radical or a propylene radical which can be substituted by alkyl groups having 1 to 4 carbon atoms, characterized in that the methyl derivatives of the corresponding but-2-en-4-ol-1-al-acetal of the formula II , ■ Bp - 0. ■ ι ^ CH - C = C - CH ₀ - OH (II), RO _R 2 _R 1 1 4
in which R to R have the meaning given above, with a pyridine-sulfur trioxide complex in dimethyl sulfoxide 3 0 9851/1117 -18- and in the presence of triethylamine or with a pyridine-chromium trioxide complex, or oxidized with manganese dioxide or nickel per oxide in an inert solvent. 9 · Process for the preparation of methyl-fumar-dialdehyde-monoacetals of formula I. u CH -C = CC (I) R ⁴ - O ^ 12 Il ^ O
η η 1 2
in which R and R are different and are either a hydrogen atom or a methyl group and Yr and R together are a propylene radical which can be substituted by alkyl groups having 1 to 4 carbon atoms, characterized in that the methyl derivatives of the corresponding but-2 -en-4-ol-l-al-acetals of the formula II Y? - 0 <^
u ^ CH -C = C- CH ₀ - OH (II) ^E - ° R ² k ¹ 1 4
in which R to R have the meaning given above, oxidized with sulfuric acid chromic acid solution in acetone. 10. Process for the preparation of methyl-fumaric dialdehyde monoacetals of formula I. Έ? - 0 \ YES i, CH-C = C-C ^; (I) R-o '2; i. ^^ o π ti 1 2
in which R and R are different and either a water -5 mean 4 atomic atoms or a methyl group and Br and R are identical or different and each mean an aliphatic hydrocarbon radical with 1 to 4 carbon atoms or a phenyl radical, characterized in that a 4-alkoxymethyl-crotonaldehyde of the formula III R ^ - 0 - CH - C = C - (Τ (III), 0 _R 2 _R l 0 in which R to Br have the meaning given above, by heating with excess acetic anhydride and an alkali acetate, carbonate or hydroxide or a non-aromatic bicyclic amine into a butadiene diol derivative 309851/1117 -19- -19-. 'ο.ζ. 29 178 R ⁵ - O - CH = C - C = CH - 0 - CO - CH ^. (IV), IpI-] P- ^RR '■ ■ 1 "5 In which R to R ^ have the meaning given above, converted, and this initially at temperatures from -70 to +10 ⁰ C with chlorine or bromine in a solvent inert under the reaction conditions and then at temperatures from -20 ⁰ C to +10 ° c with a strong base and an alcohol with 1 to 4 carbon atoms or phenol. Badische Anilin- & Soda-Pabrik AG »Α 3 0 9 8 5 1/1 1.17.