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Novel method for asymmetric alpha-hydroxylation of photo-oxygenation beta-dicarbonyl compound based on C-2' phase transfer catalyst

A technology of dicarbonyl compound and phase transfer catalyst, applied in the field of organic synthesis, can solve the problems of harsh requirements and low catalytic activity, and achieve the effects of high catalytic activity, good substrate applicability and environmental friendliness

Inactive Publication Date: 2016-07-06
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to the relatively low catalytic activity of the triethyl phosphite / oxygen system and the harsh environmental requirements for substrates and solvents, the application of this method is limited.
Although scientists have done a lot of fruitful work on the α-hydroxylation of β-dicarbonyl compounds, it is still a great challenge to use molecular oxygen as an oxidant in this reaction to realize the reaction process.

Method used

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  • Novel method for asymmetric alpha-hydroxylation of photo-oxygenation beta-dicarbonyl compound based on C-2' phase transfer catalyst
  • Novel method for asymmetric alpha-hydroxylation of photo-oxygenation beta-dicarbonyl compound based on C-2' phase transfer catalyst
  • Novel method for asymmetric alpha-hydroxylation of photo-oxygenation beta-dicarbonyl compound based on C-2' phase transfer catalyst

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0030] Preparation of Ia-1 (Ia, R 1 is phenyl, R 2 for Br, R 3 for Br)

[0031]

[0032] Add 10ml of ether into a 100ml three-necked flask, stir 4.0g of bromobenzene, slowly add 10.4ml of n-butyllithium, react at -10°C for two hours, then add dropwise 50ml of cinchonine (3.0g) solution dissolved in ether, continue Stir for an hour. After warming to room temperature, the reaction was stirred for an additional two hours until complete. The reaction was quenched with acetic acid, and 50ml of water and 50ml of ethyl acetate were added. Subsequently, 2.5 g of elemental iodine was added until all solids dissolved, followed by 1.0 g of Na 2 S 2 o 5 , the mixture was adjusted to alkaline with 20% ammonia water. The organic phase was washed with water, dried over anhydrous sodium sulfate, and spin-dried. Crude product column chromatography (15% MeOH, 2% Et 3 N, 40% EtOAcinPE), followed by recrystallization from ethyl acetate to give 0.80 g of white solid (Cn-1). 1 HNMR (5...

Embodiment 2

[0034] Preparation of Ia-2 (Ia, R 1 is 4-trifluoromethylphenyl, R 2 for Br, R 3 for Br)

[0035]

[0036] In a 100ml three-necked flask, add 10ml of ether, stir 5.5g of 4-trifluoromethylbromobenzene, slowly add 10.4ml of n-butyllithium, react at -10°C for two hours, then dropwise add 50ml of diethyl ether-dissolved cinchonine (3.0 g) solution, stirring was continued for one hour. After warming to room temperature, the reaction was stirred for an additional two hours until complete. The reaction was quenched with acetic acid, and 50ml of water and 50ml of ethyl acetate were added. Subsequently, 2.5 g of elemental iodine was added until all solids dissolved, followed by 1.0 g of Na 2 S 2 o 5 , the mixture was adjusted to alkaline with 20% ammonia water. The organic phase was washed with water, dried over anhydrous sodium sulfate, and spin-dried. Crude product column chromatography (15% MeOH, 2% Et 3 N, 40% EtOAcinPE), followed by recrystallization from ethyl acetate...

Embodiment 3

[0038] Preparation of Ia-3 (Ia, R 1 is 4-trifluoromethylphenyl, R 2 for CF 3 , R 3 for CF 3 )

[0039]

[0040] Into a 100ml three-necked flask, add 0.24g of Cn-2, 20ml of tetrahydrofuran, and 0.31g of 3,5-trifluoromethylbenzyl bromide. The reaction was heated to reflux for 10 hours. After the reaction was completed, it was cooled to room temperature, poured into 50ml of diethyl ether, filtered, and the solid was recrystallized from methanol / diethyl ether to obtain 0.31g of Ia-3 with a yield of 76%. 1 HNMR (500MHz, Methanol-d 4 )δ8.59–8.38(m,6H),8.32–8.20(m,2H),7.97–7.79(m,4H),6.69(d,J=2.6Hz,1H),6.13(m,1H),5.48 –5.39(m,1H),5.38–5.24(m,3H),4.58(ddd,J=11.7,8.4,2.8Hz,1H),4.12(dt,J=34.5,10.1Hz,2H),3.61(t ,J=11.3Hz,1H),3.23–3.11(m,1H),2.78–2.53(m,2H),2.07–1.84(m,3H),1.21(m,1H).

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Abstract

The invention belongs to the technical fields of organic synthesis and provides a novel method for asymmetric alpha-hydroxylation of a photo-oxygenation beta-dicarbonyl compound based on a C-2' phase transfer catalyst.The beta-dicarbonyl compound, the cinchona alkaloid C-2' phase transfer catalyst and an organic photosensitizer are stirred in a solvent, alkali is added, strong stirring reaction is performed in the air under the condition of visible light, the reaction temperature is 50-70 DEG C, the reaction time is 1-4 hours, and a chiral alpha-hydroxyl-beta-dicarbonyl compound with the yield no lower than 70% and the enantiomeric excess selectivity no lower than 60% ee is obtained; derivatization is conducted on a cheap cinchona alkaloid C-2' potential easy to obtain a series of chiral phase transfer catalysts having higher catalytic activity, molecules are successively oxidized into an oxidant, and the asymmetric alpha-hydroxylation of the photo-oxygenation beta-dicarbonyl compound is achieved.The method has good substrate applicability and environmental friendliness.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, and relates to a novel C-2′ phase transfer catalyst photooxidative β-dicarbonyl compound asymmetric α-hydroxylation method. Background technique [0002] Optically active ɑ-hydroxy-β-dicarbonyl compounds are a very important structural unit, which widely exist in natural products, chiral pharmaceuticals and pesticide intermediates. It is worth mentioning that (S)-5-chloro-1-oxoindene-2-hydroxy-2-carboxylic acid methyl ester is an important intermediate of the pesticide indoxacarb. Davis first reported the method of using Davis reagent to obtain chiral α-hydroxyl-β-dicarbonyl compound in 1981 (Tetrahedron Lett.1981, 22, 4385-4388), but the method is cumbersome to operate, the reaction conditions are relatively harsh, and excessive use of Chiral oxidizing agent has high cost and is not suitable for production application. [0003] In recent years, researchers have reported a large numbe...

Claims

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Application Information

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IPC IPC(8): C07C69/757C07C67/31C07C235/82C07C231/12C07D453/04B01J31/02C07B41/02
CPCB01J31/0244B01J31/0271B01J2231/70C07B41/02C07B2200/07C07C67/31C07C231/12C07D453/04C07C69/757C07C235/82
Inventor 孟庆伟王亚坤唐晓飞杨帆武玉峰赵静喃
Owner DALIAN UNIV OF TECH
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