Synthesis method of (2E, 4Z)-2, 4-decadienoic acid ethyl ester

Abstract

The invention discloses a synthesis method of (2E, 4Z)-2, 4-decadienoic acid ethyl ester, and belongs to the technical field of perfume synthesis. Comprising the following steps: 3-octyne-1-alcohol is oxidized by ephedrine to obtain 2-octyne aldehyde; the preparation method comprises the following steps: carrying out aldol condensation on 2-octyne aldehyde and malonic acid, and carrying out decarboxylation reaction to obtain E-dec-2-ene-4-acetylenic acid; carrying out esterification reaction on the obtained carboxylic acid to obtain E-dec-2-ene-4-acetylenic acid ethyl ester; and carrying out cis-reduction on the eneynoic acid ester to obtain the (2E, 4Z)-2, 4-decadienoic acid ethyl ester. The synthesis method has the advantages of simplicity in operation, few three wastes and high selectivity, the yield and the product quality are guaranteed, and the synthesis method is more suitable for industrial large-scale production.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of perfume synthesis, and particularly relates to a synthesis method of (2E,4Z)-2,4-decadienoic acid ethyl ester. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing the understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art that is already known in any country in the world.

[0003] (2E,4Z)-2,4-decadienoic acid ethyl ester (CAS: 3025-30-7) is a colorless to light yellow liquid organic substance with pear, grass, apple and other fruit-like sharp aroma. Natural product exists in fruits such as apples, pineapples and Bartlett pear. (2E,4Z)-2,4-decadienoic acid ethyl ester is an indispensable flavor ingredient in the food, cosmetic, daily chemical product and perfume industries due to its unique aroma characteristics.

[0004] The prior art adopts 3,3-dimethoxy-1-propynyl and halogenated pentane as raw materials, and then carries out substitution reaction, hydrolysis reaction and hydrogenation reaction in sequence to obtain trans-2-cis-4-decadienoic acid ethyl ester. The Wittig reaction of 2-octanal with triethyl phosphonoacetate in the presence of a basic substance B to obtain 4-alkynyl trans-2-decenoic acid ethyl ester is involved, and the basic substance B is butyllithium, phenyllithium, sodium hydride, sodium hydroxide, sodium amide or sodium ethoxide. The use of triethyl phosphonoacetate not only increases the production cost, but also does not comply with the principle of atomic economy. The generation of organic phosphorus byproducts also increases the difficulty of post-treatment. In the prior art, n-hexanal is used as the starting material, and after three-step chemical conversion, the key intermediate 1-bromoheptene is prepared, and then the coupling reaction of 1-bromoheptene and ethyl acrylate is carried out under the catalysis of a metal catalyst to obtain (E,Z)-2,4-decadienoic acid ethyl ester. The use of bromine has the following defects: the toxicity and volatility of bromine bring safety hazards to the production process; due to the active chemical properties of the dibromo intermediate, side reactions such as elimination and substitution are easy to occur; all bromine atoms in the reaction cannot be retained in the final product, and the atomic utilization rate is not high.

[0005] The prior art in preparing (2E,4Z)-2,4-decadienoic acid ethyl ester still has the following main problems: 1. using equivalent or excess manganese oxide or aluminum oxide and other metal oxides, and generating a large amount of solid waste in the post-treatment process; 2. generating active intermediates such as allenes, and more byproducts are easy to be generated in the reaction process; 3. poor selectivity of cis-trans isomers, and it is difficult to obtain high-purity (2E,4Z)-2,4-decadienoic acid ethyl ester product. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a synthesis method of (2E, 4Z)-2,4-decadienoic acid ethyl ester, which has the advantages of simpler operation, less waste, high selectivity, guaranteed yield and product quality, and is more suitable for industrial scale-up production.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions: A synthesis method of (2E, 4Z)-2,4-decadienoic acid ethyl ester, comprising the following steps: Step 1: 2-octyn-1-ol undergoes Miyaura oxidation to obtain 2-octynaldehyde; Step 2: After the aldol condensation and decarboxylation of 2-octynaldehyde and malonic acid in the presence of a base reagent, E-dec-2-ene-4-ynoic acid is obtained; Step 3: The obtained carboxylic acid undergoes esterification to obtain E-dec-2-ene-4-ynoic acid ethyl ester; Step 4: The enynoate is subjected to cis-reduction to obtain (2E, 4Z)-2,4-decadienoic acid ethyl ester.

[0008] The synthesis route provided by the present application utilizes Miyaura oxidation reaction to obtain conjugated aldehyde, and the aldehyde with this structure is more stable, thereby realizing the production of the final product with higher yield.

[0009] Preferably, in step 1, in the Miyaura oxidation reaction, the molar ratio of the catalyst to 2-octyn-1-ol is 3:8~12; the catalyst used is a combination of ferric nitrate or its hydrate, a piperidine-based nitroxyl radical and sodium chloride; the molar ratio of ferric nitrate or its hydrate, a piperidine-based nitroxyl radical and sodium chloride is 0.8~1.2:0.8~1.2:0.8~1.2.

[0010] In the embodiments of the present application, the catalysts are compared, and it is found that when the ferric nitrate is replaced by copper nitrate, the yield is slightly reduced, and a higher yield is obtained based on the ferric nitrate.

[0011] Preferably, in step 1, in the Miyaura oxidation reaction, the piperidine-based nitroxyl radical in the catalyst used is 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxyl radical or 2,2,6,6-tetramethylpiperidine nitroxyl radical.

[0012] Preferably, in step 2, in the aldol condensation and decarboxylation of 2-octynaldehyde and malonic acid, the base reagent used is a combination of one or both of triethylamine and pyridine.

[0013] Preferably, in step 2, it further includes, after the reaction, diluting with dichloromethane, then slowly adding hydrochloric acid aqueous solution and stirring, extracting and separating, and removing the organic solvent by reduced pressure distillation to obtain E-dec-2-ene-4-ynoic acid.

[0014] In consideration of the post-treatment and residue of the solvent, dichloromethane is preferably used to dilute the reaction product.

[0015] Preferably, in step 3, concentrated sulfuric acid is used as the catalyst in the esterification reaction.

[0016] Preferably, in step 3, the E-deca-2-ene-4-yne acid obtained in step 2 is mixed with ethanol, and then concentrated sulfuric acid is added dropwise under stirring, and the reaction is carried out under refluxing at elevated temperature, and then the reaction is cooled to room temperature, and then part of the ethanol is removed by distillation under reduced pressure, and then the reaction product is diluted with dichloromethane, and then deionized water is added to separate the product by extraction, and then the organic solvent is removed by distillation under reduced pressure to obtain the E-deca-2-ene-4-yne acid ethyl ester.

[0017] Preferably, in step 4, Lindlar catalyst is used as the catalyst in the cis-reduction of the ene-yne ester. The reaction is carried out in the presence of hydrogen.

[0018] Compared with the prior art, the present application has the following advantages: 1. The present application provides a synthesis method as follows: 2-octyn-1-ol is subjected to the oxidation of Asahina to obtain 2-octynal, and then the aldol condensation and decarboxylation of 2-octynal and malonic acid are carried out to obtain E-deca-2-ene-4-yne acid, and then the esterification of the obtained carboxylic acid is carried out to obtain E-deca-2-ene-4-yne acid ethyl ester, and then the cis-reduction of the ene-yne ester is carried out to obtain (2E, 4Z)-2, 4-decadienoic acid ethyl ester, which overcomes the problem of poor selectivity of the cis-trans isomers in the prior art, and based on the method, the (2E, 4Z)-2, 4-decadienoic acid ethyl ester product with high purity can be obtained, and the purity of the product can reach 96%.

[0019] 2. In the reaction process provided by the present application, no basic catalyst such as sodium ethoxide is used, and the reaction of malonic acid and triethylamine or pyridine is adopted, so that the solid waste generated in the post-treatment process is reduced.

[0020] 3. The method of the present application utilizes the oxidation reaction of Asahina to obtain a conjugated alkynyl aldehyde with a more stable structure, so that the generation of by-products is reduced, and the yield of the product is improved. BRIEF DESCRIPTION OF DRAWINGS

[0021] The drawings constituting a part of the specification of the present application serve to provide a further understanding of the present application, and the illustrative embodiments of the present application and the description thereof serve to explain the present application, and do not constitute an improper limitation on the present application.

[0022] Figure 1 is the nuclear magnetic hydrogen spectrum of (2E, 4Z)-2, 4-decadienoic acid ethyl ester prepared in Example 1 of the present application; Figure 2 is a synthesis route of (2E, 4Z)-2, 4-decadienoic acid ethyl ester described in the present application. DETAILED DESCRIPTION

[0023] It should be noted that the following detailed description is illustrative only, and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0024] In some embodiments of the present application, a method for synthesizing (2E,4Z)-2,4-decadienoic acid ethyl ester is provided, and the synthetic route is shown in Figure 2 The method comprises the following steps: Step 1: 2-octyn-1-ol is subjected to the oxidation of Asahina to obtain 2-octynal; Step 2: the aldol condensation and decarboxylation of 2-octynal and malonic acid in the presence of a base reagent to obtain E-dec-2-ene-4-ynoic acid; Step 3: the esterification of the carboxylic acid obtained in Step 2 to obtain E-dec-2-ene-4-ynoic acid ethyl ester; Step 4: cis-reduction of the enynoate to obtain (2E,4Z)-2,4-decadienoic acid ethyl ester.

[0025] In some embodiments, in the Asahina oxidation reaction of Step 1, the molar ratio of the catalyst to 2-octyn-1-ol is 3:8~12; further, the catalyst used is a combination of ferric nitrate or its hydrate, a piperidine nitroxide radical and sodium chloride; wherein the molar ratio of ferric nitrate or its hydrate, a piperidine nitroxide radical and sodium chloride is 0.8~1.2:0.8~1.2:0.8~1.2.

[0026] In some embodiments, in the Asahina oxidation reaction of Step 1, the catalyst used is a combination of ferric nitrate nonahydrate, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical (4-OH-TEMPO) and sodium chloride or a combination of ferric nitrate nonahydrate, 2,2,6,6-tetramethylpiperidine nitroxide radical (TEMPO) and sodium chloride. More preferably, a combination of ferric nitrate nonahydrate, 4-hydroxy-2,2,6,6-tetramethylpiperidine nitroxide radical and sodium chloride.

[0027] In some embodiments, in Step 2, the aldol condensation and decarboxylation of 2-octynal and malonic acid, the base reagent used is a combination of one or both of triethylamine and pyridine.

[0028] In some embodiments, in Step 2, the molar ratio of 2-octynal, malonic acid and triethylamine is 1:1:1~1.5.

[0029] In some embodiments, in Step 2, the reaction temperature is 70℃±5℃.

[0030] Also included, after the reaction, adding dichloromethane to dilute, then slowly adding hydrochloric acid aqueous solution stirring, extraction separation, removal of organic solvent under reduced pressure to obtain E-dec-2-ene-4-alkyne acid.

[0031] Preferably, in step 3, the catalyst used in the esterification reaction is concentrated sulfuric acid.

[0032] In some embodiments, the E-dec-2-ene-4-alkyne acid obtained in step 2 is mixed with ethanol, and under stirring, concentrated sulfuric acid is added dropwise, and the reaction is carried out under refluxing at elevated temperature, and then cooled to room temperature. After removing part of the ethanol under reduced pressure, dilution with dichloromethane, and extraction separation with deionized water, the organic solvent is removed under reduced pressure to obtain E-dec-2-ene-4-alkyne acid ethyl ester.

[0033] In some embodiments, in step 4, the catalyst used in the cis-reduction of the ene-yne ester is Lindlar catalyst. The reaction is carried out in the presence of hydrogen. The amount of Lindlar catalyst added is 5wt%~10wt% of E-dec-2-ene-4-alkyne acid ethyl ester. In more preferred embodiments, in step 4, ethanol is used as the solvent, which has a higher yield than methanol. It is speculated that the core reason is that different solvents have different effects on the adsorption of active centers of the catalyst and the stability of reaction intermediates, or the yield fluctuation caused by the mass transfer efficiency caused by the difference in solvent polarity.

[0034] In steps 1, 3 and 4, the reaction temperature is room temperature, generally 25℃±5℃.

[0035] The detection method of the purity of (2E,4Z)-2,4-decadienoic acid ethyl ester is gas chromatography: Chromatographic column: DB-5 (30 m x 0.53 mm x 1.50 μm); Conditions: initial temperature 80℃, holding for 3 min; temperature rising rate 15℃ / min, final temperature 260℃, holding for 10 min; Injection port: 270℃, detector: 280℃; Detector: FID; Carrier gas: nitrogen; Column flow rate: 3 ml / min; Split ratio: 20:1; Hydrogen flow rate: 40 ml / min; Air flow rate: 350 ml / min; Tail gas: 25 ml / min.

[0036] The present application is further described below in conjunction with specific examples.

[0037] Example 1 The reaction process is shown in the following reaction formula:

[0038] Into a reaction flask, Fe(N03)3-9H20 (4 g, 10 mmol), 4-OH-TEMPO (1.7 g, 10 mmol), NaCI (0.58 g, 10 mmol), 2-octyn-l-ol (12.6 g, 100 mmol) and dichloromethane (300 mL) were added sequentially under oxygen atmosphere, stirred at room temperature for 24 hours until the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and the crude product was separated by column chromatography to obtain 2-octynal 10.7 g with a yield of 86%.

[0039] Into a reaction flask, 2-octynal (1.2 g, 10 mmol), malonic acid (1.0 g, 10 mmol) and triethylamine (1.2 g, 12 mmol) were added sequentially, heated to 70°C ± 5°C for 10 hours, cooled to room temperature, diluted with dichloromethane (50 mL), then slowly added with 0.5M dilute hydrochloric acid aqueous solution (15 mL) and stirred for 10 minutes, extracted and separated, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-yne acid 1.3 g with a yield of 78%.

[0040] Into a reaction flask, E-dec-2-ene-4-yne acid (1.7 g, 10 mmol) and ethanol (20 mL) were added, 2 drops of concentrated sulfuric acid were added dropwise under stirring, heated to reflux for 12 hours, cooled to room temperature, and after removing part of the ethanol by distillation under reduced pressure, diluted with dichloromethane, extracted and separated by adding deionized water, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-yne acid ethyl ester 1.7 g with a yield of 87%.

[0041] Into a reaction flask, E-dec-2-ene-4-yne acid ethyl ester (1.9 g, 10 mmol), ethanol (30 mL) and Lindlar catalyst (95 mg, 5wt%) were added sequentially, then reacted at room temperature for 14 hours in the presence of 1 atm hydrogen, filtered after the reaction was completed, and then the solvent was removed by distillation under reduced pressure, and column chromatography separation obtained (2E,4Z)-2,4-decadienoic acid ethyl ester 1.6 g with a yield of 82% and a purity of 96%.

[0042] The nuclear magnetic resonance hydrogen spectrum of the product (2E,4Z)-2,4-decadienoic acid ethyl ester is as follows: Figure 1shown,1H NMR (500 MHz, CDC13) δ 7.61 (ddd, J = 15.2, 11.7, 1.0 Hz, 1H), 6.15 - 6.09 (m, 1H), 5.92 - 5.79 (m, 2H), 4.24 - 4.18 (m, 2H), 2.35 - 2.25 (m, 2H), 1.46 - 1.39 (m, 2H), 1.34 - 1.27 (m, 7H), 0.89 (t, J = 7.0 Hz, 3H).

[0043] Comparative Example 1 The catalyst ratio in the first step in Example 1 above was reduced from 10 mmol to 5 mmol, Fe(N03)3-9H20 (2 g, 5 mmol), 4-OH-TEMPO (0.85 g, 5 mmol), NaCI (0.29 g, 5 mmol), 2-octyn-l-ol (12.6 g, 100 mmol) and dichloromethane (300 mL) to obtain 2-octynal 9.1 g with a yield of 73%.

[0044] Comparative Example 2 The catalyst in the first step in Example 1 above was replaced by Cu(N03)3-3H20 instead of Fe(N03)3-9H20, Cu(N03)3-3H20 (1.4 g, 10 mmol), 4-OH-TEMPO (1.7 g, 10 mmol), NaCI (0.58 g, 10 mmol), 2-octyn-l-ol (12.6 g, 100.0 mmol) and dichloromethane (300 mL) to obtain 2-octynal 9.8 g with a yield of 79%.

[0045] Example 2

[0046] Fe(N03)3-9H20 (4 g, 10 mmol), TEMPO (1.6 g, 10 mmol), NaCI (0.58 g, 10 mmol), 2-octyn-l-ol (12.6 g, 100 mmol) and dichloromethane (300 mL) under oxygen atmosphere, stirred at room temperature for 24 hours until the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and the crude product was separated by column chromatography to obtain 2-octynal 10.0 g with a yield of 81%.

[0047] To the reaction flask was added 2-octynal (1.2 g, 10 mmol), malonic acid (1.0 g, 10 mmol) and triethylamine (1.0 g, 10 mmol) sequentially, heated to 70 °C ± 5 °C for 10 hours, cooled to room temperature, diluted with dichloromethane (50 mL), then slowly added 0.5 M dilute aqueous hydrochloric acid (15 mL) and stirred for 10 minutes, extracted and separated, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-yne acid 1.1 g with a yield of 66%.

[0048] To the reaction flask was added E-dec-2-ene-4-yne acid (1.7 g, 10 mmol) and ethanol (20 mL), and 2 drops of concentrated sulfuric acid were added dropwise while stirring, heated to reflux for 12 hours, cooled to room temperature, and after removing part of the ethanol by distillation under reduced pressure, diluted with dichloromethane, added deionized water to extract and separate, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-yne acid ethyl ester 1.7 g with a yield of 87%.

[0049] To the reaction flask was added E-dec-2-ene-4-yne acid ethyl ester (1.9 g, 10 mmol), ethanol (30 mL) and Lindlar catalyst (190 mg, 10 wt%), then reacted at room temperature for 14 hours in the presence of 1 atm hydrogen, filtered after the reaction was completed, and the solvent was removed by distillation under reduced pressure, and column chromatography was used to separate to obtain (2E,4Z)-2,4-decadienoic acid ethyl ester 1.6 g with a yield of 82% and a purity of 96%.

[0050] Example 3:

[0051] To the reaction flask was added Fe(NO3)3·9H2O (4 g, 10 mmol), 4-OH-TEMPO (1.7 g, 10 mmol), NaCl (0.58 g, 10 mmol), 2-octyn-1-ol (12.6 g, 100 mmol) and dichloroethane (300 mL) sequentially under an oxygen atmosphere, stirred at room temperature for 24 hours until the reaction was completed, the organic solvent was removed by distillation under reduced pressure, and the crude product was separated by column chromatography to obtain 2-octynal 10.3 g with a yield of 83%.

[0052] To the reaction flask was added 2-octynal (1.2 g, 10 mmol), malonic acid (1.0 g, 10 mmol) and triethylamine (1.5 g, 15 mmol) sequentially, heated to 70 °C ± 5 °C for 10 hours, cooled to room temperature, diluted with dichloromethane (50 mL), then slowly added 0.5 M dilute aqueous hydrochloric acid (15 mL) and stirred for 10 minutes, extracted and separated, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-yne acid 1.2 g with a yield of 72%.

[0053] To the reaction flask was added E-dec-2-ene-4-yne acid (1.7 g, 10 mmol) and ethanol (20 mL), and 2 drops of concentrated sulfuric acid were added dropwise while stirring, and the reaction was heated to reflux for 12 hours, cooled to room temperature, and after removing part of the ethanol by distillation under reduced pressure, diluted with dichloromethane, added deionized water to extract and separate, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-yne acid ethyl ester 1.7 g with a yield of 87%.

[0054] To the reaction flask was added E-dec-2-ene-4-yne acid ethyl ester (1.9 g, 10 mmol), methanol (30 mL) and Lindlar catalyst (95 mg, 5 wt%), and then the reaction was carried out at room temperature for 14 hours in the presence of 1 atm hydrogen, after which the reaction was filtered and the solvent was removed by distillation under reduced pressure, and column chromatography was used to separate (2E,4Z)-2,4-decadienoic acid ethyl ester 1.5 g with a yield of 76% and a purity of 95%.

[0055] Example 4:

[0056] To the reaction flask was added Fe(NO3)3·9H2O (4 g, 10 mmol), 4-OH-TEMPO (1.7 g, 10 mmol), NaCl (0.58 g, 10 mmol), 2-octyn-1-ol (12.6 g, 100 mmol) and dichloromethane (300 mL) sequentially under an oxygen atmosphere, and stirred at room temperature for 24 hours until the reaction was complete, and the organic solvent was removed by distillation under reduced pressure, and the crude product was separated by column chromatography to obtain 2-octynal 10.7 g with a yield of 86%.

[0057] Into a reaction flask, 2-octynal (1.2 g, 10 mmol), malonic acid (1.0 g, 10 mmol) and pyridine (0.9 g, 11 mmol) were added in sequence, and the temperature was raised to 70℃±5℃ for 10 hours, and then the temperature was lowered to room temperature. Dichloromethane was added for dilution (50 mL), and then 0.5M dilute hydrochloric acid aqueous solution (15 mL) was slowly added for stirring for 10 minutes. Extraction separation was performed, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-ynoic acid 1.0 g with a yield of 60%.

[0058] Into a reaction flask, E-dec-2-ene-4-ynoic acid (1.7 g, 10 mmol) and ethanol (20 mL) were added, and 5 drops of concentrated sulfuric acid were added dropwise under stirring. The temperature was raised to reflux for 12 hours, and then the temperature was lowered to room temperature. After partial ethanol was removed by distillation under reduced pressure, dichloromethane was added for dilution, deionized water was added for extraction separation, and the organic solvent was removed by distillation under reduced pressure to obtain E-dec-2-ene-4-ynoic acid ethyl ester 1.6 g with a yield of 82%.

[0059] Into a reaction flask, E-dec-2-ene-4-ynoic acid ethyl ester (1.9 g, 10 mmol), ethanol (30 mL) and Lindlar catalyst (95 mg, 3wt%) were added in sequence, and then the reaction was performed at room temperature for 14 hours in the presence of 1 atm hydrogen. After the reaction was completed, filtration was performed, and then the solvent was removed by distillation under reduced pressure. Column chromatography separation was performed to obtain (2E,4Z)-2,4-decadienoic acid ethyl ester 1.5 g with a yield of 76% and a purity of 94%.

[0060] Comparative Example 3 The preparation method of (2E,4Z)-2,4-decadienoic acid ethyl ester reported in the reference (Org. Synth. 1988, 66, 22, DOI: 10.15227 / orgsyn.066.0022) was repeated.

[0061]

[0062] 1-octyn-3-ol was used as a starting material, reacted with triethyl orthoacetate to obtain 3,4-decadienoic acid ethyl ester, and then rearrangement reaction occurred at 200℃ in the presence of basic aluminum oxide to obtain (2E,4Z)-2,4-decadienoic acid ethyl ester with a yield of 67% and a purity of 90%.

[0063] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for the synthesis of (2E,4Z)-2,4-decadienoic acid ethyl ester, characterized in that, The method comprises the following steps: Step 1, 2-octyn-1-ol is subjected to a Shibusawa oxidation to obtain 2-octynal; Step 2, after the hydroxyaldehyde condensation and decarboxylation of 2-octynal and malonic acid in the presence of a base reagent, E-dec-2-ene-4-ynoic acid is obtained; Step 3, esterification of the obtained carboxylic acid to obtain E-dec-2-ene-4-ynoic acid ethyl ester; Step 4, cis-reduction of the ene-yne acid ester to obtain (2E, 4Z)-2, 4-decadienoic acid ethyl ester.

2. The process for the synthesis of (2E,4Z)-2,4-decadienoic acid ethyl ester according to claim 1, characterized in that, In step 1, in the Shibusawa oxidation reaction, the molar ratio of the catalyst to 2-octyn-1-ol is 3:8-12; the catalyst used is a combination of ferric nitrate or its hydrate, a piperidine nitroxide radical and sodium chloride; the molar ratio of ferric nitrate or its hydrate, a piperidine nitroxide radical and sodium chloride is 0.8-1.2:0.8-1.2:0.8-1.

2.

3. The process for the synthesis of (2E,4Z)-2,4-decadienoic acid ethyl ester according to claim 1, characterized in that, In step 1, in the Shibusawa oxidation reaction, the piperidine nitroxide radical in the catalyst used is 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine nitroxide or 2, 2, 6, 6-tetramethylpiperidine nitroxide.

4. The synthesis method of (2E,4Z)-2,4-decadienoic acid ethyl ester according to claim 1, characterized by, In step 2, in the hydroxyaldehyde condensation and decarboxylation of 2-octynal and malonic acid, the base used is a combination of one or both of triethylamine and pyridine. 5.The method of synthesizing (2E, 4Z) -2, 4-decadienoic acid ethyl ester according to claim 1, characterized in that, In step 2, after the reaction, dichloromethane is added for dilution, then hydrochloric acid aqueous solution is added for stirring, extraction separation is performed, and organic solvents are removed by distillation under reduced pressure to obtain E-dec-2-ene-4-ynoic acid. 6.The method of synthesizing (2E, 4Z) -2, 4-decadienoic acid ethyl ester according to claim 1, characterized in that, In step 3, in the esterification reaction, concentrated sulfuric acid is used as the catalyst. 7.The method of synthesizing (2E, 4Z) -2, 4-decadienoic acid ethyl ester according to claim 1, characterized in that, In step 3, E-dec-2-ene-4-ynoic acid obtained in step 2 and ethanol are mixed, concentrated sulfuric acid is added dropwise under stirring, the reaction is carried out under heating and reflux, the temperature is lowered to room temperature, part of the ethanol is removed by distillation under reduced pressure, then dilution is performed with dichloromethane, deionized water is added for extraction separation, and organic solvents are removed by distillation under reduced pressure to obtain E-dec-2-ene-4-ynoic acid ethyl ester. 8.The method of synthesizing (2E, 4Z) -2, 4-decadienoic acid ethyl ester according to claim 1, characterized in that, In step 4, in the cis-reduction of the ene-yne acid ester, Lindlar catalyst is used as the catalyst. 9.The method of synthesizing (2E, 4Z) -2, 4-decadienoic acid ethyl ester according to claim 1, characterized in that, In step 1, the reaction is carried out in an oxygen atmosphere; in step 4, the reaction is carried out in the presence of hydrogen. 10.The method of synthesizing (2E, 4Z) -2, 4-decadienoic acid ethyl ester according to claim 1, characterized in that, The reaction temperature in steps 1, 3 and 4 is 25℃±5℃; the reaction temperature in step 2 is 70℃±5℃.

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