Camphor Schiff base, and preparation method and application thereof

A technology of Schiff base and camphor, which is applied in the field of asymmetric synthesis of β-nitro alcohols, can solve the problems of no research reports and achieve high catalytic efficiency, high yield, and high enantioselectivity

Inactive Publication Date: 2016-04-13
SHAANXI NORMAL UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Camphor is a natural source of chirality, which has the advantages of low toxicity, low cost, and easy availability. However, there has been no research report on the use of chiral camphor Schiff base ligands for asymmetric Henry reactions.

Method used

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  • Camphor Schiff base, and preparation method and application thereof
  • Camphor Schiff base, and preparation method and application thereof
  • Camphor Schiff base, and preparation method and application thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] 1. Dissolve 5.01g (28mmol) of 1-isocyanate-2-camphorone in 100mL of absolute anhydrous methanol, cool to 0°C, add 2.6g (7mmol) of cerium trichloride heptahydrate, after the addition, the reaction solution is cooled to -78°C, add 5.3g (140mmol) sodium borohydride in batches within 1 hour, and continue to stir at -78°C for 1 hour, then the reaction solution is warmed to -40°C, and continues to stir at this temperature for 2 hours , then the temperature of the reaction solution was slowly raised to room temperature, 50mL of 6mol / L KOH aqueous solution was added to the residual solution, and heated to reflux for 3 hours, the reaction solution was cooled to room temperature, extracted with dichloromethane (3 × 100mL), and the organic phases were combined, Dry over anhydrous sodium sulfate, filter, and remove dichloromethane from the filtrate by a rotary evaporator to obtain a white camphor amino alcohol crude product, which is further separated by column chromatography (silic...

Embodiment 2

[0026] Camphor Schiff base of the present invention is applied in the asymmetric Henry reaction of cuprous chloride catalyzed 4-nitrobenzaldehyde and nitromethane, and concrete usage method is as follows:

[0027] Under nitrogen protection, add 0.014g (0.05mmol) camphor Schiff base, 0.005g (0.05mmol) cuprous chloride and 2mL tert-butanol to the reaction flask, stir at room temperature for 2 hours, then add 0.54mL (20mmol ) nitromethane, and stirred for 30 minutes, then added 0.76g (0.5mmol) 4-nitrobenzaldehyde, after the TLC detection reaction was complete, removed low boiling point components with a rotary evaporator, and the crude product was separated by column chromatography to obtain ( R)-1-(4-nitrophenyl)-2-nitroethanol, the yield is 90%, and the ee value is 84%.

Embodiment 3

[0029] Camphor Schiff base of the present invention is applied in the asymmetric Henry reaction of cuprous chloride catalyzed 3-nitrobenzaldehyde and nitromethane, and concrete usage method is as follows:

[0030] Under nitrogen protection, add 0.014g (0.05mmol) camphor Schiff base, 0.005g (0.05mmol) cuprous chloride and 2mL tert-butanol to the reaction flask, stir at room temperature for 2 hours, then add 0.54mL (20mmol ) nitromethane, and stirred for 30 minutes, then added 0.76g (0.5mmol) 3-nitrobenzaldehyde, after the TLC detection reaction was complete, removed low boiling point components with a rotary evaporator, and the crude product was separated by column chromatography to obtain ( R)-1-(3-nitrophenyl)-2-nitroethanol, the yield was 82%, and the ee value was 80%.

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Abstract

The invention discloses camphor Schiff base, and a preparation method and application of the camphor Schiff base. A structural formula of the camphor Schiff base is as shown in the description. The preparation method the camphor Schiff base comprises the steps of obtaining optically pure camphor amino alcohol through reduction and hydrolysis of 1-isocyanate-2-camphorquinone, and obtaining the camphor Schiff base by enabling the optically pure camphor amino alcohol to react with 4-hydroxyl salicylaldehyde. The camphor Schiff base disclosed by the invention can be used as a ligand so as to be used for an asymmetric Henry reaction of aromatic aldehyde and nitromethane which are catalyzed by cuprous chloride, and an obtained product, namely beta-nitroalcohol, has higher enantioselectivity and higher yield.

Description

technical field [0001] The invention belongs to the technical field of asymmetric synthesis of β-nitro alcohols, and in particular relates to a camphor Schiff base, a preparation method thereof and an application in the asymmetric Henry reaction of aromatic aldehydes and nitromethane. Background technique [0002] β-Nitroalcohol is a very important intermediate in organic synthesis. It has two very useful functional groups, nitro and hydroxyl. It can be further synthesized by functional group conversion, such as carboxylic acid, aldehyde, α-hydroxy ketone, amino alcohol, etc. Compounds; Chiral amino alcohols obtained by reducing chiral β-nitro alcohols can be used as ligands and have been widely used in asymmetric catalytic reactions. The use of chiral ligands and transition metals in the asymmetric Henry reaction is the most important and direct method for the preparation of chiral β-nitroalcohols. The chiral ligands that have been invented so far mainly include ligand typ...

Claims

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Application Information

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IPC IPC(8): C07C251/24C07C249/02B01J31/22C07C201/12C07C205/19C07C205/16C07C253/30C07C255/53C07C205/32
CPCB01J31/1805B01J31/2217B01J2231/4205B01J2531/16C07C201/12C07C213/00C07C249/02C07C251/24C07C253/30C07C215/44C07C205/19C07C205/16C07C255/53C07C205/32
Inventor 徐峰李高强焦堂乾屠静轩
Owner SHAANXI NORMAL UNIV
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