Large-steric-hindrance chiral quaternary ammonium salt phase transfer catalyst derived from quinine and synthesis method thereof

A technology of phase transfer catalyst and cinchona base, which is applied in organic chemical methods, organic compound/hydride/coordination complex catalysts, chemical instruments and methods, etc., can solve the problems of low yield and poor stability, and achieve the goal of preparing The method is simple, the cost is low, and the effect of using less catalyst

Active Publication Date: 2021-10-26
NANJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Due to the poor stability of this cinchona-modified quaternary ammonium salt under the oxidation condition of potassium permanganate, even if stoichiometric quaternary ammonium salt is used in the reaction, only moderate enantioselectivity and low yield can be achieved

Method used

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  • Large-steric-hindrance chiral quaternary ammonium salt phase transfer catalyst derived from quinine and synthesis method thereof
  • Large-steric-hindrance chiral quaternary ammonium salt phase transfer catalyst derived from quinine and synthesis method thereof
  • Large-steric-hindrance chiral quaternary ammonium salt phase transfer catalyst derived from quinine and synthesis method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0040] Preparation of catalyst C3(Ar 2 Be 3,5-di-tert-butylphenyl), its synthetic method comprises the following steps:

[0041]

[0042] Among them, Ar 2 For 3,5-di-tert-butylphenyl.

[0043] (1) Synthesis of 3,5-di(3,5-di-tert-butylphenyl)benzaldehyde: under nitrogen protection, 3,5-dibromobenzaldehyde (1.57g, 6mmol), 3,5-dibromobenzaldehyde tert-butylphenylboronic acid (12mmol) and Pd(PPh 3 ) 4 (69.3mg, 0.06mmol was dissolved in 12mLTHF (remove oxygen by bubbling). After stirring at room temperature until the solid reactant was completely dissolved, add Na 2 CO 3 (3.8 g, 36 mmol) in water (6 mL). The reaction system was heated to reflux temperature. After the reaction was completed, the mixture was filtered through celite. The filtrate was extracted 3 times with ethyl acetate. The organic phases were combined and dried over anhydrous sodium sulfate. Concentrated under reduced pressure and purified by silica gel column chromatography to obtain 3,5-bis(3,5-di-ter...

Embodiment 2

[0050] Preparation of Catalyst C4

[0051]

[0052] (1) Dissolve cinchona base (118 mg, 0.4 mmol) in toluene (6 mL), add 3,4-difluorobenzyl bromide (160 mg, 0.52 mmol), and heat to reflux for 2 hours. After the reaction was completed, N-3,4-difluorobenzyl gallonine quaternary ammonium salt I (178 mg, 89%) was obtained by silica gel column chromatography;

[0053] (2) Dissolve N-3,4-difluorobenzyl chicken sodium quaternary ammonium salt Ⅰ (178mg, 0.356mmol) in dichloromethane (6mL), add 3,5-bis(3,5-di-tert-butyl phenyl) benzyl bromide (594mg, 1.07mmol) and 50% KOH aqueous solution (100mg, 1.78mmol), reacted and separated by column chromatography to obtain N-3,4-difluorobenzyl-O- 3,5-Bis(3,5-di-tert-butylphenyl)benzyl chicken sodium base-derived quaternary ammonium catalyst C4 (267 mg, 75%).

Embodiment 3

[0055] Preparation of Catalyst C5

[0056]

[0057] (1) Synthesis of 2-bromo-3,5-di-tert-butylbenzyl bromide: 3,5-di-tert-butyltoluene (409 mg, 2.0 mmol) was dissolved in anhydrous CH 3 CN, add FeCl successively at room temperature 3 (65 mg, 0.4 mmol) and NBS (374 mg, 2.1 mmol). The reaction was heated to 82°C and stirring was continued for 4 hours. After the reaction, the resulting solution was cooled to room temperature, and the solvent was removed by rotary evaporation.

[0058] The crude product was purified by silica gel column chromatography using petroleum ether as the eluent to obtain 2-bromo-3,5-di-tert-butyltoluene with a yield of 89%. Dissolve 2-bromo-3,5-di-tert-butyltoluene (468mg, 2.0mmol) in cyclohexane, add NBS (324mg, 2.06mmol) and BPO (13mg, 0.066mmol) successively at room temperature, and heat to 80 °C, reflux for 4 hours. After the reaction was completed, the solvent was removed by rotary evaporation. The crude product was purified by silica gel co...

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Abstract

The invention discloses a large-steric-hindrance chiral quaternary ammonium salt phase transfer catalyst derived from quinine as well as a synthesis method and application thereof, belonging to the technical field of asymmetric catalysis. The synthesis method comprises the following steps: dissolving quinine in an organic solvent, adding benzyl bromide, and conducting reacting to obtain an N-benzyl quinine quaternary ammonium salt catalyst; and dissolving a product obtained in the previous step in an organic solvent, adding corresponding large-steric-hindrance benzyl bromide and an inorganic alkali solution, conducting reacting, and performing purifying to obtain the large-steric-hindrance chiral quaternary ammonium salt catalyst derived from quinine. When the large-steric-hindrance catalyst is applied to a reaction for synthesizing chiral alpha-hydroxy-beta-keto ester by oxidizing olefin with potassium permanganate, the enantioselectivity of the product alpha-hydroxy-beta-keto ester can be remarkably improved.

Description

technical field [0001] The invention relates to the field of asymmetric catalysis, in particular to a cinchona base-derived bulky chiral quaternary ammonium phase transfer catalyst, a synthesis method and application thereof. Background technique [0002] Cinchona alkaloids, as Bronsted bases, are excellent organic catalysts in the field of synthetic chemistry, and their derivatives have attracted widespread attention. Cinchonine (Cinchonine, CN), Cinchonidine (Cinchonidine, CD), Quinine (Quinine, QN) and Quinidine Ding (Quinidine, QD) can be extracted from cinchona bark. These four structures are the most commonly used structural units in cinchona alkaloid phase transfer catalysts, and a large number of phase transfer catalysts can be prepared by modifying them. [0003] Since Dolling et al first used cinchona base quaternary ammonium salt as a chiral phase transfer catalyst to catalyze the asymmetric alkylation reaction of cyclic indenone substrates in 1984, the reaction ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D453/04B01J31/02C07C67/313C07C69/716C07C201/12C07C205/43C07C69/738
CPCC07D453/04B01J31/0239B01J31/0244B01J31/0271C07C67/313C07C201/12C07B2200/07C07C69/716C07C205/43C07C69/738Y02P20/584
Inventor 王超李娟李双庆
Owner NANJING UNIV OF TECH
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