Synthesis method of menthalactone

A synthesis method and a technology for mentholide, applied in directions such as organic chemistry, can solve problems such as unsuitable large-scale preparation and industrial production, harsh reaction conditions, and many synthesis steps, and achieve mild reaction conditions, good yield, and simplified preparation process. Effect

Active Publication Date: 2013-01-02
CHINA TOBACCO HUNAN INDAL CORP
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Problems solved by technology

These methods for synthesizing mentholactone have certain stereoselectivity, but there are many synthetic steps, or the shortcomings of rare raw materials and high preparation costs
Tanabe et al. reported the method of titanium tetrachloride / tri-n-butylamine to promote the condensation of 3-methylcyclohexanone and 1,1-dimethoxyacetone to prepare mentholactone [6] , the synthesis reaction is only one step, but it needs to be carried out at -78°C under the protection of dehydration and argon in the reaction system, the reaction conditions are harsh, and it is not suitable for large-scale preparation and industrial production

Method used

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  • Synthesis method of menthalactone

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Embodiment 1

[0024] 2.0 g of 3-methylcyclohexanone, 3.0 g of pyruvate and 2.0 g of anhydrous ferric chloride powder were mixed in a 100 mL single-necked bottle, and stirred and reacted at 90° C. for 6 h. GC-MS detection reaction progress. After the reaction was completed, 70 mL of dichloromethane was added to the reaction mixture, the solid salt was filtered off with suction, the dichloromethane layer was washed with saturated brine, the solvent was evaporated under reduced pressure, and 10% sodium hydroxide solution was added at 50°C. Saponify for 3 hours, then cool the water bath temperature to 5°C, add 0.4 g of sodium borohydride solid in batches, wait for it to rise to room temperature naturally, stir for a total of 5 hours, acidify the solution with 20% sulfuric acid to pH = 1, and extract water with dichloromethane layer, concentrated, and purified by column chromatography to obtain 1.70 g of mentholactone with a yield of 57%. The spectral data of mentholactone is: 1 H NMR:δ0.91-1....

Embodiment 2

[0026] 2.0 g of 3-methylcyclohexanone, 1.0 g of pyruvate and 1.5 g of anhydrous copper chloride were mixed in a 100 mL single-necked bottle, and stirred and reacted at 95° C. for 4 h. GC-MS detection reaction progress. After the reaction is complete, add 70 mL of dichloromethane to the reaction mixture, filter off the solid salt, wash the dichloromethane layer with saturated brine, evaporate the solvent under reduced pressure, add 10% sodium hydroxide solution and saponify at 50°C After 3 hours, cool the temperature of the water bath to 5°C, add 0.4 g of solid sodium borohydride in batches, wait for it to rise to room temperature naturally, stir for a total of 5 hours, acidify the solution with 20% sulfuric acid to pH = 1, and extract the water layer with dichloromethane , concentrated, and purified by column chromatography to obtain 0.82 g of mentholactone, with a yield of 55%.

Embodiment 3

[0028] 2.0 g of 3-methylcyclohexanone, 3.0 g of pyruvate and 2.0 g of anhydrous aluminum trichloride powder were mixed in a 100 mL single-necked bottle, and stirred and reacted at 90° C. for 6 h. GC-MS detection reaction progress. After the reaction was completed, 70 mL of dichloromethane was added to the reaction mixture, the solid salt was filtered off with suction, the dichloromethane layer was washed with saturated brine, the solvent was evaporated under reduced pressure, and 10% sodium hydroxide solution was added at 50°C. Saponify for 3 hours, then cool the water bath temperature to 5°C, add 0.4 g of sodium borohydride solid in batches, wait for it to rise to room temperature naturally, stir for a total of 5 hours, acidify the solution with 20% sulfuric acid to pH = 1, and extract water with dichloromethane layer, concentrated, and purified by column chromatography to obtain 0.36 g of mentholactone, with a yield of 12%.

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Abstract

The invention discloses a synthesis method of menthalactone [5,6,7,7a-tetrahydro-3,6-dimethyl-2(4H)-benzofuranone], wherein the method comprises the following steps: using 3-methyl cyclohexanone and pyruvate as raw materials, performing aldol condensation reaction under a catalytic function of Lewis acid to obtain 2-(2-oxo-4-methyl cyclohexylidene)propionate, performing saponification and then reducing by sodium borohydride and acidifying to obtain the menthalactone. The synthesis method provided by the invention has advantages of simple synthesis process, mild reaction condition, concise operation and environmental protection, and is suitable for industrial production of the menthalactone on a large scale.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis and flavors and fragrances, in particular to a method for synthesizing mentholactone [5,6,7,7a-tetrahydro-3,6-dimethyl-2(4H)-benzofuranone] method. Background technique [0002] Mentholactones are trace components of peppermint oil, and their intense sweet, bean flavor exhibits the characteristic qualities of premium peppermint oil [1] , it can be used as an additive for food (FEMA 3764) and cigarettes, and also as an intermediate for the synthesis of dihydromentholactone, menthol furan, etc. [0003] The synthesis of mentholactone has attracted widespread attention. In 2002, Ferraz reviewed its synthesis. The starting materials include D-menthafuran, D-citronellal, L-isopulegol, geraniol and nerol, 4- Methylcyclohexanone, (1R,5R)-5-methylcyclohex-2-en-1-ol, 3-methylcyclohexanone, etc. [2] Afterwards, Bates et al., Tsubuki et al. reported respectively to obtain (5R)-5-methyl-2-vinylid...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D307/83
Inventor 陈雄杨华武苏利霞黎艳玲谭新良卢红兵刘金云
Owner CHINA TOBACCO HUNAN INDAL CORP
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