A two-step synthesis method for preparing C15 alcohol for canthaxanthin

Abstract

The invention discloses a two-step synthesis method of C15 alcohol for preparing canthaxanthin, wherein the synthesis method uses 4-oxo-β-ionone as a raw material, reacts with an acetylene Grignard reagent under low temperature and in an organic solvent, and hydrolyzes with a protonic acid to obtain 3-[3-hydroxy-3-methyl-penta-1-yne-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one. Under a solvent, a Lindela catalyst is used for catalytic hydrogenation reaction to obtain 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one. The preparation method of the invention has the advantages of low raw material price, few reaction steps, mild reaction conditions, environmental friendliness, ease of operation, high reaction yield, and easy industrialization.

Description

Technical Field

[0001] The invention relates to the technical field of an intermediate for synthesizing canthaxanthin, and in particular to a two-step synthesis method of C15 alcohol for preparing canthaxanthin. Background Art

[0002] Canthaxanthin is a carotenoid widely found in nature. It is also the earliest important feed additive to be commercialized. Its industrial chemical synthesis is of great significance. Canthaxanthin is a type of oxygen-containing carotenoid, with a chemical name of 4,4'-diketo-β-carotene. It can be used in chicken feed to color "three yellow chickens" and egg yolks, and is a "three red type" colorant. The main function of canthaxanthin in feed is to provide animal food with the same nutritional, disease-resistant and health-care effects on the human body after it enters the human food chain. The currently industrialized canthaxanthin synthesis route mainly synthesizes β-carotene through various methods, and then performs an oxidation reaction to synthesize canthaxanthin. Canthaxanthin produced by this type of process is usually accompanied by a large number of side reactions, and it is difficult to obtain high-purity canthaxanthin.

[0003] The present invention relates to the synthesis of 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one, an intermediate in the chemical synthesis of canthaxanthin. The product is a precursor for preparing a C15 phosphonate fragment of canthaxanthin and an important intermediate for preparing high-purity canthaxanthin.

[0004] At present, the main methods for preparing 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one are to use α-ionone as a raw material, react with peroxy acid for epoxidation, react with a strong base for ring opening to obtain 4-hydroxy β-ionone, and then react with a vinyl Grignard reagent to obtain 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-ol, and then oxidize the hydroxyl group to obtain 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one. The reaction route is as follows:

[0005]

[0006] This route has obvious defects. On the one hand, the route is long and involves four steps of reaction, and the total reaction yield is only 40%. The metal organic reaction step of the vinyl Grignard reagent requires the use of an excess of vinyl Grignard reagent, and the post-treatment requires a large amount of acid for neutralization. Finally, the oxidation reaction will produce a large amount of aluminum-containing wastewater. The process is complicated and polluting, making it difficult to achieve industrialization. Summary of the invention

[0007] In order to overcome the deficiencies of the prior art, the object of the present invention is to provide a two-step synthesis method for preparing C15 alcohol of canthaxanthin, the raw materials used are cheap and readily available, the reaction conditions are mild, the reaction yield is high, and the method is suitable for industrial production.

[0008] The purpose of the present invention is achieved by the following technical solutions:

[0009] A two-step synthesis method for preparing C15 alcohol of canthaxanthin, the reaction route of the synthesis method is as follows:

[0010]

[0011] Wherein, the synthesis method comprises the following steps:

[0012] 1) Under the protection of inert gas, add 4-oxo-β-ionone as shown in Formula 1 and an organic solvent into a reaction bottle, stir to dissolve, cool, and dropwise add a metal acetylide;

[0013] 2) After the addition is complete, the reaction is continued, and then a protonic acid is added dropwise for hydrolysis;

[0014] 3) After the hydrolysis is completed, the temperature is raised to room temperature, the aqueous phase is removed after layering, and the organic phase is concentrated and distilled to obtain 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one as shown in Formula 2.

[0015] 4) 3-[3-Hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one is placed in a high-pressure hydrogenation reactor, dissolved with a solvent, and a Lindela catalyst is added; after replacing with nitrogen, hydrogen is pressed in, and catalytic hydrogenation is performed to obtain 3-[3-hydroxy-3-methyl-pent-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-en-1-one as shown in Formula 3.

[0016] Further, in step 1), the metal acetylide is one of ethynylmagnesium chloride, ethynylmagnesium bromide, and ethynylmagnesium iodide, preferably ethynylmagnesium bromide. The organic solvent is one of tetrahydrofuran, ether, 1,4-dioxane, 2-methyltetrahydrofuran, isopropyl ether, methyl ethyl ether, cyclopentyl methyl ether, benzene, toluene, and xylene, or a combination of two or more thereof, preferably tetrahydrofuran.

[0017] Furthermore, in step 1), after cooling to -60 to -30°C, metal acetylide is added dropwise, and the reaction temperature is -70 to 0°C.

[0018] Furthermore, in step 1), the molar ratio of the 4-oxo β-ionone to the metal acetylide is 1:1.0 to 3.0, preferably 1:1.2.

[0019] Furthermore, in step 2), the dropping time is 30 to 60 minutes, and the hydrolysis reaction time is 30 to 60 minutes.

[0020] Further, in step 2), the protonic acid is one or a combination of two or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, potassium hydrogen sulfate, sodium hydrogen sulfate, sodium dihydrogen phosphate or potassium dihydrogen phosphate. The amount of the protonic acid is 1.0 to 1.5 times the molar amount of the metal acetylide, preferably 1.0 times.

[0021] Furthermore, in step 3), the reaction is continued for 1 to 3 hours.

[0022] Furthermore, in step 4), after adding the Lindela catalyst, the temperature is raised to 30-40° C.; the pressure of the hydrogen gas is 0.1-1.0 MPa.

[0023] Furthermore, in step 4), the solvent is one of methanol, ethanol, isopropanol, dichloromethane or chloroform, preferably methanol.

[0024] Further, in step 4), the mass ratio of the 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one to the Lindela catalyst is 100:1 to 5, preferably 100:5 (20:1); and the catalytic hydrogenation reaction time is 2 to 6 hours.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The invention provides a method for preparing 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one. The compound can be used for industrial production of canthaxanthin. 4-oxo-β-ionone is used as a raw material, reacted with an acetylene Grignard reagent under low temperature and in an organic solvent, and hydrolyzed with a protonic acid to obtain 3-[3-hydroxy-3-methyl-penta-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one. In a solvent, a Lindela catalyst is used for catalytic hydrogenation reaction to obtain 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one. The preparation method of the invention has the advantages of low raw material price, few reaction steps, mild reaction conditions, environmental friendliness, easy operation, high reaction yield, and easy industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the intermediate product 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one of Example 1;

[0028] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the product 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-en-1-one in Example 1. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form a new embodiment.

[0030] Example 1

[0031] A two-step synthesis method for preparing C15 alcohol of canthaxanthin comprises the following steps:

[0032] 1) Under nitrogen protection, add 55.0g (purity 93.63%, 0.25mol) 4-oxo-β-ionone and 1000mL tetrahydrofuran to a 2000mL three-necked flask, stir and dissolve. Measure 576mL (concentration 0.52mol / L, 0.3mol, molar ratio of 4-oxo-β-ionone to ethynylmagnesium bromide Grignard reagent is 1:1.2) ethynylmagnesium bromide Grignard reagent in a constant pressure dropping funnel, cool to below -30℃ and add Grignard reagent dropwise. The addition takes 1.5h. After the addition of Grignard reagent, keep the reaction at -50~-30℃ for 2h.

[0033] 2) After the reaction is completed, 147 g of 10% sulfuric acid is added dropwise for 30 minutes.

[0034] 3) After the sulfuric acid was added dropwise, the mixture was heated to room temperature and allowed to stand for stratification for 20 min. The lower aqueous phase was separated and the upper organic phase was concentrated to recover tetrahydrofuran. The mixture was separated by column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) to obtain 45.5 g of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one with a purity of 97.1% and a yield of 76.09%.

[0035] The obtained 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one is a light yellow oil, and its H NMR spectrum is as follows: Figure 1 As shown, the H NMR spectrum data are as follows: 1H NMR(600MHz, CDCl3) δ6.55(d,J=16.1Hz,1H),5.76(d,J=16.1Hz,1H),2.66(s,1H),2 .53(t,J=6.9Hz,2H),1.88(t,J=6.8Hz,2H),1.82(s,3H),1.67(s,3H),1.18(s,6H). HRMS:C 15 H 20 NO2Na for[M+Na] + :calculated:255.1355found:255.1369.

[0036] 4) The above 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one was dissolved in 1000 ml of methanol and transferred to a 2L high-pressure hydrogenation reactor. 2.5 g of Lindela catalyst (the mass ratio of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one to Lindela catalyst was 18.2:1) was added. After nitrogen conversion 3 times, vacuum was drawn and hydrogen was pressed in at 0.1 MPa. The temperature was raised to 30°C and stirred for reaction. The internal temperature was controlled at 30-40°C during the reaction process. After 6 hours of reaction, the pressure was released and the reaction liquid was discharged. The catalyst was separated by suction filtration, and the solution was concentrated and distilled under reduced pressure at 50°C. Column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) was used to obtain 39.5 g of 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one with a purity of 99.1% and a yield of 87.84%.

[0037] The obtained 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-en-1-one is a light yellow oil, and its H NMR spectrum is as follows: Figure 2 As shown, the H NMR data are as follows: 1H NMR (600 MHz, Chloroform-d) δ 6.20 (d, J = 16.3 Hz, 1H), 5.93 (dd, J = 17.3, 10.6 Hz, 1H), 5.65 (d, J = 16.3 Hz, 1H), 5.21 (d, J = 17.3 Hz, 1H), 5.03 (d, J = 10.6 Hz, 1H), 2.41 (t, J = 6.9 Hz, 2H), 1.76 (t, J = 6.8 Hz, 2H), 1.70 (s, 3H), 1.38 (s, 3H), 1.07 (s, 6H). HRMS: C15H22NO2Na for [M + Na] +: calculated 257.1526, found 257.1526

[0038] Example 2

[0039] A two-step synthesis method for preparing C15 alcohol of canthaxanthin comprises the following steps:

[0040] 1) Under nitrogen protection, add 55.0g (purity 93.63%, 0.25mol) 4-oxo-β-ionone, 500mL ether and 500mL tetrahydrofuran to a 2000mL three-necked flask, stir and dissolve. Measure 193mL (concentration 1.29mol / L, 0.25mol, molar ratio of 4-oxo-β-ionone to ethynylmagnesium chloride Grignard reagent is 1:1) ethynylmagnesium chloride Grignard reagent in a constant pressure dropping funnel, cool to -30℃ and add ethynylmagnesium chloride Grignard reagent dropwise. The addition takes 1.5h. After the addition of the Grignard reagent, keep the reaction at -50~-30℃ for 2h.

[0041] 2) After the reaction is completed, 30.41 g of 30% hydrochloric acid is added dropwise over a period of 20 minutes.

[0042] 3) After the hydrochloric acid was added dropwise, the mixture was heated to room temperature and allowed to stand for stratification for 30 min. The lower aqueous phase was separated, and the upper organic phase was concentrated to recover ether and tetrahydrofuran. The mixture was separated by column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) to obtain 42.25 g of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one with a purity of 97.2% and a yield of 74.89%.

[0043] 4) The above 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one was dissolved in 1000 ml of ethanol, transferred to a 2L high-pressure hydrogenation reactor, added with 2.11 g of Lindela catalyst (the mass ratio of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one to Lindela catalyst was 20:1), converted with nitrogen three times and then vacuumed, and hydrogen was pressed into 1 MPa. The temperature was raised to 40°C and stirred for reaction. The internal temperature was controlled at 30-40°C during the reaction process. After reacting for 2 hours, the pressure was released and the reaction liquid was discharged. The catalyst was separated by suction filtration, and the solution was concentrated and distilled under reduced pressure at 50°C. Column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) was used to obtain 39.9 g of 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one with a purity of 99.2% and a yield of 86.12%.

[0044] Example 3

[0045] A two-step synthesis method for preparing C15 alcohol of canthaxanthin comprises the following steps:

[0046] 1) Under nitrogen protection, add 41.26g (purity 93.63%, 0.2mol) 4-oxo-β-ionone and 1000mL toluene to a 2000mL three-necked flask and stir to dissolve. Measure 159mL (concentration 1.26mol / L, 0.2mol) and 155mL (concentration 1.29mol / L, 0.2mol) of ethynyl magnesium chloride Grignard reagent to obtain a mixed reagent, and place it in a constant pressure dropping funnel, wherein the molar ratio of 4-oxo-β-ionone to the mixed reagent is 1:2. Cool to -50℃ and add the mixed reagent dropwise. The addition takes 1h. After the mixed reagent is added, keep it warm at -50℃ for 1h.

[0047] 2) After the reaction is completed, 196 g of 10% sulfuric acid is added dropwise for 40 minutes.

[0048] 3) After the sulfuric acid was added dropwise, the mixture was heated to room temperature and allowed to stand for 20 min to separate the lower aqueous phase. The upper organic phase was concentrated to recover toluene and separated by column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) to obtain 34.33 g of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one with a purity of 96.9% and a yield of 73.58%.

[0049] 4) The above 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one was dissolved in 1000 ml of methanol, transferred to a 2L high-pressure hydrogenation reactor, and 0.34 g of Lindela catalyst was added (the mass ratio of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one to Lindela catalyst was 100:1). After switching with nitrogen three times, the mixture was evacuated and 0.8 MPa of hydrogen was pressed in. The temperature was raised to 30°C and stirred for reaction. The temperature was controlled at 30-40°C during the reaction. After 6 hours of reaction, the pressure was released and the reaction solution was discharged. The catalyst was separated by filtration, and the solution was concentrated and distilled under reduced pressure at 50°C. Column chromatography (silica gel, 200-300 mesh; developing agent, petroleum ether) was used to obtain the following: Figure 2 The obtained 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-en-1-one was 25.59 g, with a purity of 97.3% and a yield of 83.76%.

[0050] Example 4

[0051] A two-step synthesis method for preparing C15 alcohol of canthaxanthin comprises the following steps:

[0052] 1) Under nitrogen protection, add 41.26g (purity 93.63%, 0.2mol) 4-oxo-β-ionone and 1000mL tetrahydrofuran to a 2000mL three-necked flask, stir and dissolve. Measure 465mL (concentration 1.29mol / L, 0.6mol, molar ratio of 4-oxo-β-ionone to ethynylmagnesium bromide Grignard reagent is 1:3) ethynylmagnesium bromide Grignard reagent in a constant pressure dropping funnel, cool to -45℃ and drop the Grignard reagent. The dropwise addition takes 2h. After the Grignard reagent is added, keep the reaction at -40℃ for 3h.

[0053] 2) After the reaction is completed, 480 g of 10% hydrobromic acid is added dropwise for 30 minutes.

[0054] 3) After the hydrobromic acid is added dropwise, the mixture is allowed to stand for 30 min after the temperature rises to room temperature to separate the layers. The lower aqueous phase is separated and the upper organic phase is concentrated to recover tetrahydrofuran. The tetrahydrofuran is separated by column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) to obtain Figure 1 The obtained 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one was 36.6 g, with a purity of 98.7% and a yield of 76.52%.

[0055] 4) The above 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one was dissolved in 1000 ml of methanol, transferred to a 2L high-pressure hydrogenation reactor, and 1.22 g of Lindela catalyst was added (the mass ratio of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one to Lindela catalyst was 30:1). After switching with nitrogen three times, the mixture was evacuated and 0.5 MPa of hydrogen was pressed in. The temperature was raised to 30°C and stirred for reaction. The temperature was controlled at 30-40°C during the reaction. After reacting for 2 hours, the pressure was released and the reaction solution was discharged. The catalyst was separated by filtration, and the solution was concentrated and distilled under reduced pressure at 50°C. Column chromatography (silica gel, 200-300 mesh; developing agent, petroleum ether) was used to obtain the following: Figure 2 The obtained 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-en-1-one was 31.1 g, with a purity of 99.1% and a yield of 86.46%.

[0056] Example 5

[0057] A two-step synthesis method for preparing C15 alcohol of canthaxanthin comprises the following steps:

[0058] 1) Under nitrogen protection, add 61.9g (purity 93.63%, 0.3mol) 4-oxo-β-ionone and 1000mL isopropyl ether to a 2000mL three-necked flask, stir and dissolve. Measure 692mL (concentration 0.52mol / L, 0.36mol, molar ratio of 4-oxo-β-ionone to ethynylmagnesium bromide Grignard reagent is 1:1.2) ethynylmagnesium bromide Grignard reagent in a constant pressure dropping funnel, cool to below -30℃ and drop the Grignard reagent. The dropwise addition takes 2h. After the Grignard reagent is added, keep the reaction at -30℃ for 3h.

[0059] 2) After the reaction is completed, 176.4 g of 10% sulfuric acid is added dropwise for 30 minutes.

[0060] 3) After the sulfuric acid was added dropwise, the mixture was heated to room temperature and allowed to stand for stratification for 20 min. The lower aqueous phase was separated and the upper organic phase was concentrated to recover isopropyl ether. The mixture was separated by column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) to obtain 55.34 g of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one with a purity of 98.2% and a yield of 77.13%.

[0061] 4) The above 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one was dissolved in 1000ml methanol, transferred to a 2L high-pressure hydrogenation reactor, added with 2.8g of Lindela catalyst (the mass ratio of 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one to Lindela catalyst was 20:1), converted with nitrogen three times and then vacuumed, and hydrogen was pressed in at 0.5MPa. The temperature was raised to 30℃ and stirred for reaction, and the internal temperature was controlled at 30-40℃ during the reaction process. After 4h of reaction, the pressure was released and the reaction liquid was discharged. The catalyst was separated by suction filtration, and the solution was concentrated and distilled under reduced pressure at 50°C. Column chromatography (silica gel, 200-300 mesh; developing solvent, petroleum ether) was used to obtain 47.68 g of 3-[3-hydroxy-3-methyl-penta-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-ene-1-one with a purity of 98.4% and a yield of 88.37%.

[0062] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A two-step synthesis method for preparing C15 alcohol of canthaxanthin, characterized in that: The reaction route is as follows: ； Wherein, the synthesis method comprises the following steps: 1) Under the protection of an inert gas, add 4-oxo-β-ionone shown in Formula 1 and an organic solvent into a reactor, stir to dissolve, cool, and dropwise add a metal acetylide. After the dropwise addition is complete, continue the reaction; 2) Then add protonic acid to hydrolyze; 3) After the hydrolysis is completed, the temperature is raised to room temperature, the aqueous phase is removed after separation, and the organic phase is concentrated and distilled to obtain 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one shown in formula 2; 4) 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one is placed in a high-pressure hydrogenation reactor, dissolved with a solvent, and a Lindela catalyst is added; after replacing with nitrogen, hydrogen is pressed in, and catalytic hydrogenation is performed to obtain 3-[3-hydroxy-3-methyl-pent-1,4-dienyl]-2,4,4-trimethyl-cyclohex-2-en-1-one as shown in Formula 3; In step 1), the metal acetylide is one or a combination of two or more selected from acetylenic magnesium chloride, acetylenic magnesium bromide, and acetylenic magnesium iodide; the organic solvent is one or a combination of two or more selected from tetrahydrofuran, ethyl ether, 1,4-dioxane, 2-methyltetrahydrofuran, isopropyl ether, methyl ethyl ether, cyclopentyl methyl ether, benzene, toluene, and xylene; In step 1), after cooling to -50 to -30°C, metal acetylide is added dropwise, the reaction temperature is -50 to -30°C, and the molar ratio of the 4-oxo β-ionone to the metal acetylide is 1:1.0 to 3.0; In step 2), the dropping time is 30-60 min, and the hydrolysis reaction time is 30-60 min; In step 2), the protonic acid is one or a combination of two or more of hydrochloric acid, hydrobromic acid, hydroiodic acid, sulfuric acid, phosphoric acid, potassium hydrogen sulfate, sodium hydrogen sulfate, sodium dihydrogen phosphate or potassium dihydrogen phosphate; the molar amount of the protonic acid is 1.0 to 1.5 times the molar amount of the metal acetylide.

2. The two-step synthesis method for preparing C15 alcohol of canthaxanthin according to claim 1, characterized in that: In step 4), the pressure of the hydrogen gas is 0.1-1.0 MPa.

3. The two-step synthesis method for preparing C15 alcohol of canthaxanthin according to claim 1, characterized in that: In step 4), the solvent is one or a combination of two or more of methanol, ethanol, isopropanol, dichloromethane or chloroform.

4. The two-step synthesis method for preparing C15 alcohol of canthaxanthin according to claim 1, characterized in that: In step 4), the mass ratio of the 3-[3-hydroxy-3-methyl-pent-1-yn-4-enyl]-2,4,4-trimethyl-cyclohex-2-en-1-one to the Lindela catalyst is 100:1-5; and the catalytic hydrogenation reaction time is 2-6 hours.

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