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Method for preparing 4-acetoxy-2-methyl-2-butene-1-aldehyde

An acetoxy and methyl technology, applied in the field of preparation of key intermediates of vitamin A, can solve the problems of long route and complicated operation, and achieve the effects of high content and yield, mild reaction system and concise route

Inactive Publication Date: 2012-01-11
SHAOXING UNIVERSITY +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0009] This route has already been industrialized, so it is of great significance, but its disadvantage is that the route is longer and the operation is cumbersome, so there is still room for improvement about this route; for example, the Grignard reagent of vinyl bromide or vinyl chloride can be directly used to condense with 2 The tertiary alcohol 4 was obtained instead of the original two steps of condensation and reduction (Tetrahedron Letters, 45(1), 107-109; 2004; Journal of Organic Chemistry, 54(18), 4273-5; 1989)

Method used

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  • Method for preparing 4-acetoxy-2-methyl-2-butene-1-aldehyde
  • Method for preparing 4-acetoxy-2-methyl-2-butene-1-aldehyde

Examples

Experimental program
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Effect test

Embodiment 1

[0020] Example 1: Preparation of 2-methyl-2-acetoxy-3-buten-1-al 7.

[0021] Add 1N hydrochloric acid aqueous solution (50ml) into a 250ml three-necked flask with a reflux condenser, keep it warm in an oil bath, and under magnetic stirring, add 5 (50g, 0.21mol) dropwise at 75-80°C, and the dropwise addition is completed in about 30 minutes, and continue to keep warm Stir for about 2 hours, the reaction is basically completed by gas chromatography, add toluene (100ml) for extraction, separate layers, wash the organic layer with aqueous sodium bicarbonate until neutral, dry over anhydrous magnesium sulfate, distill off the solvent under reduced pressure to obtain a crude product, the crude product is reduced to Pressure distillation, collecting 45~50℃ / 2.0mmHg fractions to obtain colorless transparent liquid 8 (28.9g, 91.3%), GC content 94.2%.

[0022] GC-MS(m / z): 143, 113, 71, 55, 43(100%); IR(ν / cm -1 ): 1744, 1235; 1 HNMR (CDCl 3 )δ: 1.544 (s, 3H); 2.171 (s, 3H); 5.338-5.438...

Embodiment 2

[0023] Example 2: Preparation of 4-acetoxy-2-methyl-2-butene-1-al 1 (pentacarbon aldehyde 1).

[0024] Add 7 (23.0g, 0.15mol), solvent acetonitrile (25ml) and bisacetonitrile palladium chloride (0.2g) into a 250ml three-necked flask, keep warm in an oil bath, and keep warm at 55-60°C for about 48h under magnetic stirring. Chromatography traced that the reaction was basically completed, the reaction solution was distilled under reduced pressure to remove the solvent, the crude product was distilled under reduced pressure, and the 70-75°C / 1.5mmHg fraction was collected to obtain a colorless transparent liquid 1 (18.6g, 80.7%) with a GC content of 92.3%. 1 HNMR (CDCl 3 )δ: 1.804 (s, 3H); 2.123 (s, 3H); 4.865-4.912 (m, 2H); 6.480-56.513 (m, 1H); 9.458 (s, 1H).

Embodiment 3

[0025] Example 3: Preparation of 2-methyl-2-acetoxy-3-buten-1-al 7.

[0026] Add 1N sulfuric acid aqueous solution (150ml) into a 250ml three-necked flask with a reflux condenser, keep it warm in an oil bath, and under magnetic stirring, add 5 (50g, 0.21mol) dropwise at 55-65°C, and the dropwise addition is completed in about 30 minutes, and continue to keep warm Stir for about 2 hours, the reaction is basically completed by gas chromatography, add toluene (100ml) for extraction, separate layers, wash the organic layer with aqueous sodium bicarbonate until neutral, dry over anhydrous magnesium sulfate, distill off the solvent under reduced pressure to obtain a crude product, the crude product is reduced to Pressure distillation, collecting 45~50℃ / 2.0mmHg fractions to obtain colorless transparent liquid 8 (24.9g, 78.0%), GC content 93.4%. The proton nuclear magnetic spectrum is identical with embodiment 1.

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Abstract

The invention discloses a method for preparing 4-acetoxy-2-methyl-2-butene-1-aldehyde. The method is characterized by comprising the following steps: firstly, hydrolyzing 2-methyl-2-acetoxy-1,1-dimethoxy-3-butene to obtain 2-methyl-2-acetoxy-3-butene-1-aldehyde; and then, carrying out rearrangement reaction on the obtained 2-methyl-2-acetoxy-3-butene-1-aldehyde to obtain 4-acetoxy-2-methyl-2-butene-1-aldehyde. The method disclosed by the invention has the advantages of concise route, mild reaction system and high product content and yield.

Description

Technical field: [0001] The present invention relates to a preparation method of a key intermediate of vitamin A, more specifically a preparation of 4-acetoxy-2-methyl-2-butene-1-aldehyde (hereinafter referred to as five-carbon aldehyde) method. Background technique: [0002] Vitamin A (V A ) and its derivatives are an important class of drugs, where V A Carboxylate derivatives such as V A Acetate and palmitate are widely used in drugs, food additives and feed additives. The products of major companies in the world are marked with V A Carboxylate-based ((Encyclopedia of Chemical Engineering) Editorial Committee, Encyclopedia of Chemical Engineering, Chemical Industry Press, first edition in 1996, Vol.16, P719-729), 4-acetoxy-2-methyl-2 -Butene-1-aldehyde (hereinafter referred to as five-carbon aldehyde) is a C characterized by Wittig reaction 15 +C 5 Route Synthesis V A The key intermediate of ester, therefore, the research on the synthesis of five-carbon aldehyde ha...

Claims

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Application Information

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IPC IPC(8): C07C69/145C07C67/293
Inventor 沈润溥虞国棋于绪平胡四平吴春雷
Owner SHAOXING UNIVERSITY
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