An alcohol sweet milky compound, a preparation method thereof and a fruity milky fragrance base

Abstract

The present application relates to the field of essence and flavor technology, and particularly relates to an alcohol sweet milk flavor compound, a preparation method thereof and a fruity milk flavor base. The alcohol sweet milk flavor compound has the following structural formula: The alcohol sweet milk flavor compound prepared by the present application is 4-methyl-1-ethyl-2-hydroxy-3-cyclohexene carboxylic acid methyl ester, the compound has alcohol sweet milk flavor, slightly with plum acid, cool and elegant, so that the compound shows important practical value in the field of essence and flavor, especially in the development of tropical fruit flavor essence and the application of daily chemicals. The preparation method of the compound adopts acid catalyzed aldol condensation reaction to construct enone skeleton in one step, the reaction condition is mild, the operation is simple, the post-treatment is simple, the production efficiency is high, and the method is suitable for industrial production. The fruity milk flavor base prepared by the present application is added with the alcohol sweet milk flavor compound, and has alcohol sweet milk flavor, slightly with plum acid, cool and elegant.

Description

Technical Field

[0001] This invention relates to the field of fragrance and flavor technology, specifically to a sweet and creamy flavor compound, its preparation method, and a fruity and creamy flavor base. Background Technology

[0002] Currently, the most common milky-scented compounds in the domestic and international fragrance and flavor markets are alkyl lactones, butanedione, and ethyl maltol. While these compounds can exhibit basic milky aroma characteristics, they generally suffer from problems such as a single aroma, short-lasting scent, and a lack of naturalness and richness. Especially when constructing complex aroma systems with a "sweet milky aroma" combined with fruity and cooling sensations, existing raw materials are insufficient to meet the fragrance requirements of high-quality fragrances. Furthermore, milky-scented compounds with a cyclohexene skeleton and multiple substitutions of hydroxyl, ester, and alkyl groups have not yet been reported. Therefore, developing a compound with a novel structure, a unique aroma (combining sweet milky aroma, plum tartness, and cooling sensation), long-lasting scent, and a simple synthesis process has significant market value and application prospects. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a sweet, creamy compound. This compound has a rich, sweet aroma with a slight plum tartness and a refreshing coolness.

[0004] Another objective of this invention is to provide a method for preparing the above-mentioned alcoholic sweet milk flavor compound. This method employs an acid-catalyzed aldol condensation reaction to construct an enone skeleton in one step. The reaction conditions are mild, the operation is simple, the post-processing is straightforward, and the production efficiency is high, making it suitable for industrial production.

[0005] Another object of the present invention is to provide a fruity milk flavor base. This fruity milk flavor base contains the aforementioned sweet milk flavor compound, possessing a rich, sweet aroma with a slight plum tartness and a refreshing coolness.

[0006] The objective of this invention is achieved through the following technical solution: a sweet, milky-flavored compound having the following structural formula: .

[0007] The sweet, creamy compound can be named: methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate.

[0008] Another objective of this invention is achieved through the following technical solution: a method for preparing a sweet, milky flavor compound, comprising the following steps: Step 1: Using methyl 2-ethylacetoacetate and butenone as raw materials, 3-ethyl-3-methoxycarbonyl-2,6-heptanedione is prepared by Michael addition reaction. The structural formula of 3-ethyl-3-methoxycarbonyl-2,6-heptanedione is shown below: ; Step 2: Using 3-ethyl-3-methoxycarbonyl-2,6-heptadecane obtained in Step 1 as a raw material, methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate was prepared by intramolecular aldol condensation reaction under phosphoric acid catalysis and heating conditions. The structural formula of methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate is shown below: ; Step 3: Using methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate obtained in Step 2 as a raw material, a sweet and creamy compound is prepared by selective reduction of ketone carbonyl under the condition of sodium borohydride as a reducing agent. The sweet and creamy compound is methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate.

[0009] The key to the preparation method of the sweet, creamy compound of this invention lies in the acid-catalyzed intramolecular aldol condensation reaction in step two, which constructs the enone cyclohexene skeleton in one step. To overcome the problems of traditional base catalysis systems being sensitive to ester groups in the substrate and prone to side reactions, this invention systematically screened various protic acids and found that phosphoric acid with a mass fraction of 80-90% can efficiently catalyze the cyclization of this specific substrate without causing ester hydrolysis or racemic side reactions. The moderate acidity and protonation ability of phosphoric acid can preferentially promote the formation of enol intermediates with higher substitution degrees, thereby precisely controlling the regioselectivity of cyclization and directly dehydrating to obtain the α,β-unsaturated cyclohexenone structure. Compared with conventional base catalysis or other strong acids (such as sulfuric acid and p-toluenesulfonic acid), the phosphoric acid catalysis system of this invention has the advantages of mild reaction conditions, simple post-processing, and stable yield, providing an efficient and practical new route for constructing cyclic enone skeletons from substrates containing acid-sensitive functional groups.

[0010] Furthermore, in step one, the preparation method of 3-ethyl-3-methoxycarbonyl-2,6-heptadecane includes the following steps: A1. Sodium iodide and cerium trichloride heptahydrate are loaded into a reaction apparatus and mixed. Then, methyl 2-ethyl acetoacetate and butenone are added in sequence. The mixture is stirred at room temperature for 46-50 hours. A2. After the reaction is complete, the system is filtered through silica gel and the silica gel is washed with ethyl acetate. The filtrates are combined and concentrated to obtain a yellow oily liquid, which is 3-ethyl-3-methoxycarbonyl-2,6-heptadecane.

[0011] Furthermore, in step A1, the molar ratio of methyl 2-ethylacetoacetate to butenone is 1:1.1-1.3.

[0012] Furthermore, in step two, the preparation method of methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate includes the following steps: B1. Place the 3-ethyl-3-methoxycarbonyl-2,6-heptanedione obtained in step one into a reaction apparatus, add phosphoric acid solution, and heat to 60-70℃ for 1-3 hours. B2. After the reaction was completed, the mixture was cooled to room temperature and then poured into ice water. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were washed with saturated sodium chloride, dried with anhydrous sodium sulfate, concentrated by rotary evaporation, and separated by silica gel column chromatography to obtain methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate.

[0013] Furthermore, the phosphoric acid solution contains 80-90% phosphoric acid by mass, and the feeding ratio of 3-ethyl-3-methoxycarbonyl-2,6-heptadecane to phosphoric acid solution is 2-5 mL of phosphoric acid solution for every 1 g of 3-ethyl-3-methoxycarbonyl-2,6-heptadecane.

[0014] Furthermore, in step three, the preparation method of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate includes the following steps: C1. Dissolve the 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylic acid methyl ester obtained in step 2 in methanol and place it in a reaction apparatus. Cool it to -1~1℃, and then slowly add sodium borohydride in batches. After the addition is complete, keep the reaction at -1~1℃ for 25-35 min, and then raise the temperature to room temperature to continue the reaction for 1-3 h. C2. After the reaction is completed, the reaction is quenched with saturated brine, and then the liquid phase is separated. The aqueous phase is extracted with diethyl ether, the organic phases are combined and washed successively with saturated sodium chloride, dried with anhydrous sodium sulfate, concentrated by rotary evaporation, and separated by silica gel column chromatography to obtain the alcoholic sweet milk flavor compound, which is methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate.

[0015] Furthermore, in step C1, the molar ratio of the total amount of sodium borohydride to methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate is 0.7-8:1.

[0016] Another objective of the present invention is achieved through the following technical solution: a fruity milk flavor base, comprising the above-mentioned sweet milk flavor compound.

[0017] Furthermore, the fruity milk flavor base comprises the following raw materials in parts by weight: 25-35 parts of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate, 8-12 parts of ethyl maltol, 12-18 parts of peach aldehyde, 20-30 parts of propyldecyl lactone, 2-8 parts of trans-2-hexenal, 1-3 parts of geraniol acetate, 3-5 parts of leaf alcohol, 16-20 parts of ethyl butyrate, 2-6 parts of isoamyl butyrate, 75-85 parts of γ-caprolactone, 20-30 parts of ethyl hexanoate, 75-85 parts of furanone acetate, 6-10 parts of allyl hexanoate, 20-26 parts of ethyl heptaate, 15-25 parts of furanone, 2-8 parts of freshly pressed lemon oil, and 600-700 parts of propylene glycol.

[0018] The beneficial effects of this invention are as follows: (1) The sweet and creamy compound obtained by this invention is methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate. This compound has a unique aroma characteristics of mellow sweetness, slight plum tartness, and cool and refreshing sensation. It has an elegant aroma and long-lasting fragrance. It has important application value and market prospects in the field of fragrances and flavors, especially in fruit-scented fragrances and daily chemical products.

[0019] (2) The preparation method provided by the present invention adopts acid-catalyzed aldol condensation reaction to construct an enone skeleton in one step, which avoids the destruction of the ester group of the substrate by the traditional base catalysis system. The reaction conditions are mild, the operation is simple, the post-processing is simple, and the production efficiency is high, making it suitable for industrial production.

[0020] (3) The fruity milk flavor base prepared by the present invention contains the sweet milk flavor compound. Compared with the flavor base without the addition of the compound, it has a more prominent sweet milk flavor, elegant plum sourness and coolness, and the overall aroma quality of the flavor base is significantly improved. Attached Figure Description

[0021] Figure 1 The photon spectrum of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate prepared in Example 1 is shown.

[0022] Figure 2 The carbon spectrum of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate prepared in Example 1 is shown. Detailed Implementation

[0023] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention.

[0024] Example 1 This embodiment provides a sweet, milky flavor compound with the following structural formula: .

[0025] The chemical name of the sweet, creamy flavoring compound is: methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate.

[0026] The preparation method of the sweet, milky flavor compound includes the following steps: Step 1: Using methyl 2-ethylacetoacetate and butenone as raw materials, 3-ethyl-3-methoxycarbonyl-2,6-heptanedione is prepared via Michael addition reaction. The chemical reaction formula for the preparation of 3-ethyl-3-methoxycarbonyl-2,6-heptanedione is as follows:

[0027] A1. Sodium iodide (5 g, 33.5 mmol, 10 mol%) and cerium trichloride heptahydrate (25 g, 67 mmol, 20 mol%) were loaded into a reaction apparatus and mixed. Then, methyl 2-ethylacetoacetate (50 mL, 347 mmol) and butenone (35 mL, 420 mmol, 1.2 equiv) were added sequentially, and the mixture was stirred at room temperature for 48 h. The structural formula of butenone is shown in Formula 1, and the structural formula of methyl 2-ethylacetoacetate is shown in Formula 2. A2. After the reaction is complete, the system is filtered through silica gel and the silica gel is washed with ethyl acetate. The filtrates are combined and concentrated to obtain a yellow oily liquid (73 g). No further purification is required, and the next reaction can be carried out. The yellow oily liquid is 3-ethyl-3-methoxycarbonyl-2,6-heptadecane, with a yield of 98%. The structural formula of 3-ethyl-3-methoxycarbonyl-2,6-heptadecane is shown in Formula 3.

[0028] The 3-ethyl-3-methoxycarbonyl-2,6-heptadecane prepared in this example has the following NMR spectral characteristics: 1 H NMR (400 MHz, CDCl3) δ 4.11 (s, 3H), 2.49 – 2.33 (m, 2H), 2.18 –2.11 (m, 1H), 2.15 (s, 3H), 2.12 (s, 3H), 2.03 (ddd, J = 14.3, 9.8, 5.9 Hz, 1H), 1.36 – 1.32 (m, 2H), 1.26 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, CDCl3) δ 207.5, 205.6, 172.8, 61.2, 58.5, 38.8,30.1, 28.4, 26.2, 19.5, 13.2. The mass spectrometry analysis data are as follows: HRMS (ESI / [M + Na] + ) calculated for C 11 H 18 NaO4: 237.1097, found237.1100. Step 2: Using 3-ethyl-3-methoxycarbonyl-2,6-heptadecane obtained in Step 1 as a raw material, methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate is prepared by intramolecular aldol condensation reaction under phosphoric acid catalysis and heating conditions. The chemical reaction formula of methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate is as follows:

[0029] B1. Place the 3-ethyl-3-methoxycarbonyl-2,6-heptanedione (17 g, 81 mmol, 1.0 equiv) obtained in step one into a reaction apparatus, add 50 mL of 85% phosphoric acid solution, and heat to 65°C for 2 h. B2. After the reaction was completed, the mixture was cooled to room temperature and then poured into ice water. The aqueous phase was then extracted with ethyl acetate (3 × 50 mL), i.e., 50 mL of ethyl acetate was used for extraction each time, for a total of 3 extractions. The combined organic phases were washed sequentially with saturated sodium chloride, dried over anhydrous sodium sulfate, concentrated by rotary evaporation, and separated by silica gel column chromatography (200-300 mesh, n-hexane / ethyl acetate = 20:1). Specifically, silica gel with a particle size of 200-300 mesh was used as the stationary phase, and a solution of n-hexane and ethyl acetate mixed in a volume ratio of 20:1 was used as the eluent. The cyclized product methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexene carboxylate (9.6 g) was obtained, with a yield of 61%. The structural formula of methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexene carboxylate is shown in Formula 4.

[0030] The methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate prepared in this example has the following NMR spectral characteristics: 1 H NMR (400 MHz, CDCl3) δ 5.93 (s, 1H), 4.12 (s, 3H), 2.55 – 2.47 (m,2H), 2.24 – 2.19 (m, 1H), 1.93 (s, 3H), 1.90 – 1.82 (m, 1H), 1.38 – 1.35 (m,2H), 1.21 (t, J = 7.1 Hz, 3H). 13 C NMR (101 MHz, CDCl3) δ 196.7, 172.8, 161.4, 125.8, 61.1, 52.0,33.3, 28.8, 24.1, 20.5,13.1. The mass spectrometry analysis data are as follows: HRMS (ESI / [M + Na] + ) calculated for C 11 H 16 NaO3: 219.0992, found219.0990. Step 3: Using methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenic acid obtained in Step 2 as a raw material, a sweet, creamy flavor compound is prepared by selective reduction of the ketone carbonyl group under the condition of sodium borohydride as a reducing agent. The sweet, creamy flavor compound is methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenic acid. The chemical reaction formula for the preparation of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenic acid is as follows:

[0031] C1. Dissolve methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate (19.6 g, 100 mmol) obtained in step 2 in methanol (150 mL) and place it in a reaction apparatus. Cool to 0°C, and then slowly add sodium borohydride in portions, wherein the total amount of sodium borohydride is 2.84 g (i.e., the total amount of sodium borohydride is 75 mmol, 0.75 equiv). After the addition is complete, keep the reaction at 0°C for 30 min, and then raise the temperature to room temperature and continue the reaction for 2 h. C2. After the reaction was completed, the reaction was quenched with saturated brine, and then the mixture was separated. The aqueous phase was extracted with ether (3 × 100 mL), i.e., 100 mL of ether was used for extraction of the aqueous phase each time, for a total of 3 extractions. The organic phases were combined and washed successively with saturated sodium chloride (100 mL), dried with anhydrous sodium sulfate, concentrated by rotary evaporation, and separated by silica gel column chromatography (200-300 mesh, n-hexane / ethyl acetate = 10:1). Specifically, silica gel with a particle size of 200-300 mesh was used as the stationary phase, and a solution of n-hexane and ethyl acetate mixed in a volume ratio of 10:1 was used as the eluent. The column chromatography yielded an alcoholic sweet milk flavor compound (18.8 g), which was methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate, with a yield of 95%.

[0032] The methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate prepared in this example has the following NMR spectral characteristics: 1H NMR (500 MHz, CDCl3) δ 5.32 (s, 1H), 4.45 (s, 1H), 4.12 (s, 3H), 1.94 (dtt, J = 20.0, 18.2, 5.7 Hz, 2H), 1.86 – 1.77 (m, 2H), 1.64 – 1.61 (m,2H), 1.26 (t, J = 7.1 Hz, 3H), 1.18 (s, 3H). 13 C NMR (126 MHz, CDCl3) δ177.8, 136.2, 123.3, 69.9, 60.8, 45.6, 28.8,27.3, 23.0, 16.6,14.3. The mass spectrometry analysis data are as follows: HRMS (ESI / [M + Na] + ) calculated for C 11 H 18 NaO3: 221.1148, found221.1144. Example 2 The aroma rating and longevity tests of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate prepared in Example 1 were performed, and the results are as follows: (1) Aroma evaluation: Twelve perfumers with more than five years of work experience made the following evaluation of the aroma of the compound: The twelve perfumers unanimously agreed that in addition to presenting the characteristic aroma of sweet milk, the compound also has the sourness of plum and a cool feeling.

[0033] (2) Scent retention test: A 10% methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexene carboxylate solution was prepared using propylene glycol as a solvent. A small amount of the solution was dipped into the scent strip and placed on the scent rack. Three perfumers smelled the scent every two hours. When two or more perfumers could not detect the scent of the scent strip, the scent retention time was recorded.

[0034] Fragrance retention tests showed that the sweet, milky aroma of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate lasted for 24 hours, while the sour, cool plum aroma lasted for 36 hours.

[0035] Example 3 This embodiment provides a fruity milk flavor base, which comprises the following raw materials in parts by weight: 30 parts of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate, 10 parts of ethyl maltol, 15 parts of peach aldehyde, 25 parts of propyldecyl lactone, 5 parts of trans-2-hexenal, 2 parts of geraniol acetate, 4 parts of leaf alcohol, 18 parts of ethyl butyrate, 4 parts of isoamyl butyrate, 80 parts of γ-caprolactone, 25 parts of ethyl hexanoate, 80 parts of furanone acetate, 8 parts of allyl hexanoate, 24 parts of furanone, 20 parts of freshly pressed lemon oil, and 646 parts of propylene glycol, which is flavor base B in Table 1.

[0036] Unlike the fruity milk flavor base (B flavor base), the A flavor base replaces the target product of this invention, methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate, with an equal amount of propylene glycol. That is, the A flavor base includes the following raw materials in parts by weight: 10 parts ethyl maltol, 15 parts peach aldehyde, 25 parts propyl decyl lactone, 5 parts trans-2-hexenal, 2 parts geraniol acetate, 4 parts leaf alcohol, 18 parts ethyl butyrate, 4 parts isoamyl butyrate, 80 parts γ-caprolactone, 25 parts ethyl hexanoate, 80 parts furanone acetate, 8 parts allyl hexanoate, 24 parts ethyl heptaate, 20 parts furanone, 5 parts freshly squeezed lemon oil, and 676 parts propylene glycol.

[0037] The formulations of the fruity milk flavor base (B flavor base) and the A flavor base are shown in Table 1 below: Table 1

[0038] Prepare fragrance base A and fragrance base B according to the formula in the table above. Add 30 parts of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate, the target product of this invention, to fragrance base B. After evaluating the fragrance base by 10 perfumers with more than 5 years of experience, the following evaluation was made: The 10 perfumers unanimously agreed that fragrance base B has a more prominent mellow sweet milky aroma than fragrance base A, with a slightly elegant plum tartness and a cooling sensation. The aroma quality of the fragrance base is significantly improved.

[0039] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A sweet, milky flavor compound, characterized in that: It has the following structural formula: 。 2. A method for preparing the alcoholic sweet milk flavor compound as described in claim 1, characterized in that: Includes the following steps: Step 1: Using methyl 2-ethylacetoacetate and butenone as raw materials, 3-ethyl-3-methoxycarbonyl-2,6-heptanedione is prepared by Michael addition reaction. The structural formula of 3-ethyl-3-methoxycarbonyl-2,6-heptanedione is shown below: ； Step 2: Using 3-ethyl-3-methoxycarbonyl-2,6-heptadecane obtained in Step 1 as a raw material, methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate was prepared by intramolecular aldol condensation reaction under phosphoric acid catalysis and heating conditions. The structural formula of methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate is shown below: ； Step 3: Using methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate obtained in Step 2 as a raw material, a sweet and creamy compound is prepared by selective reduction of ketone carbonyl under the condition of sodium borohydride as a reducing agent. The sweet and creamy compound is methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate.

3. The method for preparing the sweet, milky flavor compound according to claim 2, characterized in that: In step one, the preparation method of 3-ethyl-3-methoxycarbonyl-2,6-heptadecane includes the following steps: A1. Sodium iodide and cerium trichloride heptahydrate are loaded into a reaction apparatus and mixed. Then, methyl 2-ethyl acetoacetate and butenone are added in sequence. The mixture is stirred at room temperature for 46-50 hours. A2. After the reaction is complete, the system is filtered through silica gel and the silica gel is washed with ethyl acetate. The filtrates are combined and concentrated to obtain a yellow oily liquid, which is 3-ethyl-3-methoxycarbonyl-2,6-heptadecane.

4. The method for preparing the sweet, milky flavor compound according to claim 3, characterized in that: In step A1, the molar ratio of methyl 2-ethylacetoacetate to butenone is 1:1.1-1.

3.

5. The method for preparing the sweet, milky flavor compound according to claim 2, characterized in that: In step two, the preparation method of methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate includes the following steps: B1. Place the 3-ethyl-3-methoxycarbonyl-2,6-heptanedione obtained in step one into a reaction apparatus, add phosphoric acid solution, and heat to 60-70℃ for 1-3 hours. B2. After the reaction was completed, the mixture was cooled to room temperature and then poured into ice water. The aqueous phase was then extracted with ethyl acetate. The combined organic phases were washed with saturated sodium chloride, dried with anhydrous sodium sulfate, concentrated by rotary evaporation, and separated by silica gel column chromatography to obtain methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate.

6. The method for preparing the sweet, milky flavor compound according to claim 5, characterized in that: In step B1, the phosphoric acid solution contains 80-90% phosphoric acid by mass, and the feeding ratio of 3-ethyl-3-methoxycarbonyl-2,6-heptadecylone to phosphoric acid solution is 2-5 mL of phosphoric acid solution for every 1 g of 3-ethyl-3-methoxycarbonyl-2,6-heptadecylone.

7. The method for preparing the sweet, milky flavor compound according to claim 2, characterized in that: In step three, the preparation method of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate includes the following steps: C1. Dissolve the 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylic acid methyl ester obtained in step 2 in methanol and place it in a reaction apparatus. Cool it to -1~1℃, then add sodium borohydride in batches. After the addition is complete, keep the reaction at -1~1℃ for 25-35 min, and then raise the temperature to room temperature to continue the reaction for 1-3 h. C2. After the reaction is completed, the reaction is quenched with saturated brine, and then the liquid phase is separated. The aqueous phase is extracted with diethyl ether, the organic phases are combined and washed successively with saturated sodium chloride, dried with anhydrous sodium sulfate, concentrated by rotary evaporation, and separated by silica gel column chromatography to obtain the alcoholic sweet milk flavor compound, which is methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate.

8. The method for preparing the sweet, milky flavor compound according to claim 8, characterized in that: In step C1, the molar ratio of the total amount of sodium borohydride to methyl 4-methyl-1-ethyl-2-oxo-3-cyclohexenecarboxylate is 0.7-8:

1.

9. A fruity milk flavor base, characterized in that: Includes the sweet, creamy flavor compound as described in claim 1.

10. The fruity milk flavor base according to claim 9, characterized in that: The raw materials include the following parts by weight: 25-35 parts of methyl 4-methyl-1-ethyl-2-hydroxy-3-cyclohexenecarboxylate, 8-12 parts of ethyl maltol, 12-18 parts of peach aldehyde, 20-30 parts of propyldecyl lactone, 2-8 parts of trans-2-hexenal, 1-3 parts of geraniol acetate, 3-5 parts of leaf alcohol, 16-20 parts of ethyl butyrate, 2-6 parts of isoamyl butyrate, 75-85 parts of γ-caprolactone, 20-30 parts of ethyl hexanoate, 75-85 parts of furanone acetate, 6-10 parts of allyl hexanoate, 20-26 parts of ethyl heptaate, 15-25 parts of furanone, 2-8 parts of freshly pressed lemon oil, and 600-700 parts of propylene glycol.

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