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Green method of synthesizing 2-substituted benzoxazole compounds through biocatalysis oxidation

A technology of benzoxazole and biocatalysis, applied in the direction of organic chemistry, can solve the problems of harmful and expensive curing agents, and achieve the effect of reducing the dosage

Active Publication Date: 2018-09-28
JILIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in previous synthetic methods, the synthesis of 2-substituted benzoxazoles was prepared with harmful metal catalysts, expensive curing agents, high catalyst loading and reaction temperature

Method used

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  • Green method of synthesizing 2-substituted benzoxazole compounds through biocatalysis oxidation
  • Green method of synthesizing 2-substituted benzoxazole compounds through biocatalysis oxidation
  • Green method of synthesizing 2-substituted benzoxazole compounds through biocatalysis oxidation

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027]

[0028] In 2ml of dichloromethane, use hemoglobin as a catalyst (0.05mol% or 0.5μmol), and in the case of tert-butyl hydroperoxide as an oxidizing agent (double amount), add 110μl of benzaldehyde and 109.0mg of o-aminophenol to prepare The intermediate was stirred at room temperature for 2h. The reaction progress was detected by thin-layer chromatography, and after the reaction, the organic layer was dried and concentrated with anhydrous Na2SO4. Then it was further purified by silica gel column chromatography (ethyl acetate / hexane) to obtain 175.5 mg of 2-phenylbenzoxazole; the yield was 90%. White solid.1H NMR (500MHz, CDCl3) δ8.32–8.30(m,2H),7.83–7.81(m,1H), 7.63-7.62(m,1H),7.58-7.55(m,3H),7.40( m,2H)ppm;

Embodiment 2

[0030]

[0031] Using hemoglobin as a catalyst (0.05mol% or 0.5μmol) in 2ml of dichloromethane, in the case of tert-butyl hydroperoxide as an oxidizing agent (double amount), add p-tolualdehyde 130μl and o-aminophenol 109.0 mg The reaction was stirred at room temperature for 2h. The reaction progress was detected by thin-layer chromatography, and after the reaction, the organic layer was dried and concentrated with anhydrous Na2SO4. Then, it was further purified by silica gel column chromatography (ethyl acetate / hexane) to obtain 198.6 mg of 2-p-tolylbenzoxazole; the yield was 95%. 1H NMR (500 MHz, CDCl3) δ8.16(d, J=5.0Hz, 2H), 7.79–7.75(m,1H), 7.59–7.56(m,1H), 7.35(m,4H), 2.45(s ,3H)ppm;

Embodiment 3

[0033]

[0034] Using hemoglobin as a catalyst (0.05mol% or 0.5μmol) in 2ml of dichloromethane, in the case of tert-butyl hydroperoxide as an oxidizing agent (double amount), add 130μl of p-methoxybenzaldehyde and o-aminophenol 109.0 mg of the prepared intermediate was stirred and reacted at room temperature for 2 h. The reaction progress was detected by thin-layer chromatography, and after the reaction, the organic layer was dried and concentrated with anhydrous Na2SO4. Then, it was further purified by silica gel column chromatography (ethyl acetate / hexane) to obtain 209.2 mg of 2-p-methoxyphenylbenzoxazole; the yield was 93%. White solid. 1H NMR (500MHz, CDCl3) δ8.18 (d, J = 5.0Hz, 2H), 7.71 -7.70 (m, 1H), 7.53 (m, 1H), 7.28 (m, 2H), 6.99 (m ,2H),3.86(s,3H) ppm;

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Abstract

The invention discloses a green method of synthesizing 2-substituted benzoxazole compounds through biocatalytic oxidation, and belongs to the technical field of biocatalytic synthesis. According to the green method of synthesizing 2-substituted benzoxazole compounds through the biocatalytic oxidation, aldehyde and phenol amine or benzoxazole and cyclic secondary amine serve as reaction substrates,dichloromethane serves as solvent, and bioprotein serves as a catalyst. The green method of synthesizing 2-substituted benzoxazole compounds through the biocatalytic oxidation includes the operationsteps that firstly, the reaction substrates react to generate intermediates, then, hemoglobin, an oxidizing agent and the solvent are added into a reaction vessel, and 2-substituted benzoxazole compounds can be prepared after a mixture is stirred for 2 hours at room temperature. Through experiments, it is proved that all kinds of hemoglobin, horseradish peroxidase and heme have catalytic effects on the reaction, wherein vitreoscilla hemoglobin has the best catalytic effect, the yield reaches 91% by adopting vitreoscilla hemoglobin, and therefore the green method of synthesizing 2-substituted benzoxazole compounds through the biocatalytic oxidation is better than traditional chemical synthesis methods. By the adoption of the catalyst such as hemoglobin, no harmful reagent is used, no metalions difficult to treat are used for catalysis, and the dosage of an oxidizing agent and the dosage of the catalyst are reduced, so that the green method of synthesizing 2-substituted benzoxazole compounds through the biocatalytic oxidation is more environmentally friendly compared with the traditional chemical synthesis methods.

Description

technical field [0001] The invention belongs to the technical field of biocatalytic synthesis, in particular to a green method for synthesizing 2-substituted benzoxazole compounds by biocatalytic oxidative cyclization. Background technique [0002] 2-Substituted benzoxazoles are important scaffold molecules because they occur in a wide range of biologically active natural products and pharmaceutical preparations. Therefore, finding new methods for the synthesis of 2-substituted benzoxazoles is a hotspot in organic synthesis. 2-Substituted benzoxazoles are usually prepared by the oxidative cyclization of phenolic Schiff bases, which are formed by combining strong oxidizing agents with transition metal catalysts, such as cupric chloride, ferric chloride, alum , 4-methoxy-TEMPO and copper nanoparticles. However, in the previous synthetic methods, the synthesis of 2-substituted benzoxazoles was prepared with harmful metal catalysts, expensive curing agents, high catalyst loadi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D263/57C07D263/56C07D413/04C07D263/58
CPCC07D263/56C07D263/57C07D263/58C07D413/04
Inventor 王磊李正强李奉熙唐旭勇曹新宇
Owner JILIN UNIV
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