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Method for preparing L-menthol intermediate d-citronellal

An intermediate, citronellal technology, which is applied in the field of medicine, can solve problems such as high requirements for operation and equipment, cumbersome recycling process, etc., and achieve the effect of avoiding difficulty in catalyst recovery, reducing production costs, and simple catalyst recovery

Active Publication Date: 2013-08-21
上海统益生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the recovery process of the chiral catalyst is very cumbersome. Since the catalyst is a homogeneous catalyst, it needs to be concentrated under reduced pressure to remove the solvent, and then the product is distilled. Air and oxygen have high requirements on operation and equipment. In the early stage of the catalyst application experiment, we found that the loss of a single batch reached 10%, and the total TON value could only reach 80,000.

Method used

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  • Method for preparing L-menthol intermediate d-citronellal
  • Method for preparing L-menthol intermediate d-citronellal
  • Method for preparing L-menthol intermediate d-citronellal

Examples

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Effect test

Embodiment 1

[0043] Chiral catalyst preparation:

[0044]Under nitrogen protection, [Rh(COD)Cl] 2 (500mg, 1mmol) was dissolved in 20ml of dry tetrahydrofuran, 1,5-cyclooctadiene COD (0.54ml, 4mmol) was added, and the reaction solution was stirred for 5 minutes, then AgClO 4 (420mg), react at room temperature for 1 hour;

[0045] Under the protection of nitrogen, add PS-BINAP (2.58g) to the above reaction solution, replace nitrogen with hydrogen, keep 3atm hydrogen pressure, stir at room temperature, and detect the reaction by thin layer chromatography until PS-BINAP no longer decreases, about 12 Hour. Stop the reaction, slowly add dry toluene, and then place the reaction bottle in a 0°C refrigerator for crystallization. After removing the solvent, wash with a small amount of toluene, and dry in vacuo to obtain 2.15 g of red crystals, which is the chiral catalyst, with a yield of 80%.

[0046] The chemical structural formula is as follows:

[0047] [Rh(PS-Binap) 2 ] + [ClO 4 ] -

...

Embodiment 2

[0052] Embodiment 2 catalyst preparation

[0053] Under nitrogen protection, [Rh(COD)Cl] 2 (500mg, 1mmol) was dissolved in 20ml of dry dichloromethane, and 1,5-cyclooctadiene COD, (0.54ml, 4mmol) was added. After the reaction solution was stirred for 5 minutes, AgBF was added 4 (430mg), reflux reaction for 1 hour, the above reaction solution was added to PS-BINAP (2.58g), nitrogen was replaced with hydrogen, kept under 1atm hydrogen pressure, stirred at room temperature, TLC detection reaction, until PS-BINAP no longer reduced, After about 5 hours, stop the reaction, slowly add dry ether, and then place the reaction bottle in a 0°C refrigerator for crystallization.

[0054] After the solvent was removed, it was washed with a small amount of toluene and dried in vacuo to obtain 2.20 g of red crystals with a yield of 82%.

[0055] The chemical structural formula is as follows:

[0056] [Rh(PS-Binap) 2 ] + [BF 4 ] -

[0057] Characterized by melting point determination, ...

Embodiment 3

[0061] The preparation of embodiment 3 geranylamine

[0062]

[0063] Add the catalyst of Example 1 into a dry 100 mL reactor with sealed tubes, and replace the system with dry high-purity nitrogen for 3 times. Then add tetrahydrofuran and geranylamine, seal the system, heat to 100°C, and continue the insulation reaction for 15 hours. After the reaction, the system is cooled to room temperature, and then the reaction solution is recovered from the solvent under a reduced pressure of 400 Torr, and then filtered to remove the catalyst. The liquid was directly used in the next reaction without purification. The catalyst was recovered by filtration, washed and weighed dry, with a loss of 0.5%.

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Abstract

The invention discloses a method for preparing L-menthol intermediate d-citronellal. The method comprises the following steps of: (1) enabling geranyl amine (2) to react in a solvent A in the existence of a chiral catalyst, and then collecting myrcene amine (3) from a reaction product; and (2) carrying out acidic hydrolysis on the myrcene amine (3) to obtain d-citronellal (4). The structure of the chiral catalyst is as follows: [Rh(PS-Binap)2]<+>Y<->. The method has the characteristics of being mild in reaction condition, simple in operation, high in stereoselectivity, high in yield, simple in catalyst recovery and the like, and can be applied mechanically in cycle.

Description

technical field [0001] The invention belongs to the technical field of medicine, and relates to a synthesis method for preparing d-citronellal, an important intermediate of L-menthol. Background technique [0002] L-menthol, also known as L-menthol, its chemical name is (1R,2S,5R)-2-isopropyl-5-methyl-1-cyclohexanol, its English name is L-menthol, and its structural formula is as follows : [0003] [0004] L-menthol is a cyclic monoterpene alcohol structure substance with very obvious physiological activity, and it is widely used in medicine. Secondly, L-menthol is one of the spices with the largest demand in the world. It can be used as tobacco flavor and toothpaste essence; menthol can also be used as a flavoring agent for various foods. In addition, a large amount of L-menthol is an important raw material for the synthesis of menthyl lactate, menthylamide, lamivudine and other substances. Now the acquisition of L-menthol is mainly through two ways, one is to extrac...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C47/21C07C45/42C07C211/21C07C209/68
CPCY02P20/584
Inventor 金燕华张伟强
Owner 上海统益生物科技有限公司
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