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Method for synthesizing (1R,2S)-methyl dihydrojasmonate

A technology of methyl dihydrojasmonate and dimethyl malonate cyclopentanone is applied in the field of fragrance and essence chemistry, and can solve problems such as complicated synthesis routes and the like

Active Publication Date: 2017-07-14
北京安胜瑞力科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] Although there have been several reports on the synthesis of (1R,2S)-methyl dihydrojasmonate, the existing methods have problems such as the need for chemical doses of chiral reagents, temperature-sensitive enzymes, and cumbersome synthetic routes.

Method used

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  • Method for synthesizing (1R,2S)-methyl dihydrojasmonate

Examples

Experimental program
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Effect test

Embodiment 1

[0021] Synthesis of 2-pentylidene cyclopentanone 2

[0022] Under nitrogen protection, NaOH (0.20 g, 0.5 mmol) and 15 mL of water were added to a 100 mL four-necked flask, and stirred to dissolve. Slowly add cyclopentanone 1 (8.40 g, 100 mmol) at room temperature, and after stirring evenly, add n-valeraldehyde (5.18 g, 60 mmol) dropwise through the dropping funnel. After the dropwise addition, the stirring reaction was continued for 1 h at room temperature. After the reaction, the reaction solution was adjusted to neutrality with acetic acid. Distillation under reduced pressure gave 2-pentylidene cyclopentanone 2 (7.30 g, yield 80%) as a colorless oil. 1 H NMR (400MHz, CDCl 3 )δ6.20(t,J=6.1Hz,1H),2.80-2.71(m,2H),2.50-2.40(m,2H),2.23-2.14(m,2H),1.51-1.44(m,2H) ,1.43-1.30(m,4H),0.89(t,J=6.7Hz,3H).HRMS(APCI-TOF)calcd for C 10 h 17 O[M+H] + 153.1279, found 153.1272.

Embodiment 2

[0024] Synthesis of 2-n-pentyl-2-cyclopentenone 3

[0025] 2-Pentylidene cyclopentanone 2 (4.57 g, 30 mmol) was added into a 100 mL reaction flask, and 30 mL of a n-butanol solution containing 5% HBr was added with stirring. The reaction mixture was heated to reflux, and the stirring reaction was continued for 2h. After the reaction finished, the temperature of the reaction solution was down to room temperature, and the 2 CO 3 Aqueous solution was used to adjust the reaction solution to neutrality. Distillation under reduced pressure gave 2-n-pentyl-2-cyclopentenone 3 (3.88 g, yield 85%) as a colorless oil. 1 H NMR (400MHz, CDCl 3 )δ6.22(t,J=6.0Hz,1H),2.78-2.69(m,2H),2.50-2.42(m,2H),2.21-2.12(m,2H),1.51-1.43(m,2H) ,1.42-1.28(m,4H),0.88(t,J=6.7Hz,3H).HRMS(APCI-TOF)calcd for C 10 h 17 O[M+H] + 153.1279, found 153.1274.

Embodiment 3

[0027] Synthesis of (1S,2S)-2-n-pentyl-3-malonate dimethylcyclopentanone 4

[0028]At room temperature, add 5mL dimethyl sulfoxide and 10mL dichloromethane into a 50mL Schlenk reaction flask, add chiral amino acid lithium salt Cat.1 (0.72g, 2mmol) and 2-n-pentyl-2- Cyclopentenone 3 (1.52g, 10mmol), stir well. Dimethyl malonate (2.64 g, 20 mmol) was then added, and the reaction mixture was stirred at room temperature for 48 h. After the reaction was completed, 15 mL of saturated NaCl aqueous solution was added to extract the reaction. The organic phase was separated and the aqueous phase was extracted with ether (3 x 20 mL). The combined organic phases were washed with anhydrous Na 2 SO 4 Dry and concentrate under reduced pressure to obtain crude product. Purify by silica gel column chromatography (petroleum ether / ethyl acetate 10:1) to obtain light yellow oil (1S,2S)-2-n-pentyl-3-malonate dimethyl cyclopentanone and (1S,2S) 2R) - Mixture of 2-n-pentyl-3-malonate dimethyl...

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Abstract

The invention discloses a novel method for synthesizing (1R,2S)-methyl dihydrojasmonate by using an asymmetric Michael addition reaction. The method comprises the steps: firstly, subjecting cyclopentanone, which serves as a starting raw material, to an aldol reaction with n-valeraldehyde under alkaline conditions to produce 2-pentylidene cyclopentanone 2, and then, carrying out double-bond transposition under acidic conditions, so as to obtain 2-n-pentyl-2-cyclopentenone 3; then, carrying out a Michael addition reaction with dimethyl malonate in the presence of a chiral amino-acid lithium salt, and carrying out silicagel-column chromatographic separation twice, so as to obtain (1S,2S)-2-n-pentyl-3-dimethyl malonate cyclopentanone 4; and finally, carrying out a hydrolyzed decarboxylation reaction, thereby obtaining (1R,2S)-methyl dihydrojasmonate. According to the method, the synthesis route is simple and direct, the reaction conditions are mild, and the target compound can be prepared by only four-step reactions.

Description

technical field [0001] The invention relates to a new method for synthesizing (1R, 2S)-methyl dihydrojasmonate, which belongs to the field of perfume flavor chemistry. Background technique [0002] Methyl dihydrojasmonate (Methyl dihydrojasmonate) has strong jasmine fragrance and fruity fragrance, is widely used in cosmetics and perfume industry, and is currently the largest class of spices used (Frater, G.; Bajgrowicz, J.A.; Kraft, P. . Tetrahedron 1998, 54, 7633. Kraft, P.; Bajgrowicz, J.A.; Denis, C.; Frater, G. Angew. Chem., Int. Ed., 2000, 39, 2980.). Methyl dihydrojasmonate was first synthesized in 1962 (Firmenich, A.; Firmenich, R.; Firmenich, G.; Firmenich, R.E. Patent GB 907431A, 1962, 3, 3.). There are two chiral carbon atoms in the structure of methyl dihydrojasmonate, which has four different stereoisomers (Formula 1), and the chiral structure has an important influence on the aroma characteristics of methyl dihydrojasmonate. (1R,2S)-Methyl dihydrojasmonate has...

Claims

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Application Information

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IPC IPC(8): C07C67/347C07C67/32C07C69/716C07C45/74C07C45/67C07C49/597
CPCC07C45/67C07C45/74C07C67/32C07C67/347C07B2200/07C07C69/716C07C49/597
Inventor 张国清杨大志
Owner 北京安胜瑞力科技有限公司
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