阅读说明：本技术 一种光催化合成噻唑杂环化合物的方法 (Method for synthesizing thiazole heterocyclic compound through photocatalysis ) 是由 陈艳艳 徐燕丽 陈慧 于 2019-10-18 设计创作，主要内容包括：本发明公开了一种光催化合成噻唑杂环化合物的方法,所述方法采用炔烃和硫代酰胺为原料,在吖啶盐的催化下,在空气及室温的条件下,用蓝光灯照射,搅拌后即可得到化噻唑杂环化合物。该方法所用的原料易得,无需过渡金属和其他氧化剂的添加,仅用绿色可持续的可见光引发反应,操作简便,产率可观,环境友好,有良好的应用前景。(The invention discloses a method for synthesizing a thiazole heterocyclic compound by photocatalysis, which adopts alkyne and thioamide as raw materials, irradiates by a blue light lamp under the condition of air and room temperature under the catalysis of acridine salt, and obtains the thiazole heterocyclic compound after stirring. The method has the advantages of easily obtained raw materials, no need of adding transition metal and other oxidants, only use of green sustainable visible light to initiate reaction, simple operation, considerable yield, environmental friendliness and good application prospect.)

1. a method for synthesizing thiazole heterocyclic compounds by photocatalysis is characterized in that alkyne raw materials in a reaction general formula (I) are added with a photosensitizer, the mixture is stirred in a solvent while being irradiated by blue light, and thioamide is injected by an injection pump and is dissolved in the solvent, so that the thiazole heterocyclic compounds shown in the general formula can be obtained, wherein the solvent is one of acetonitrile, 1, 2-dichloroethane, chlorobenzene, N-dimethylformamide and dimethyl sulfoxide or a mixture of the acetonitrile, the 1, 2-dichloroethane, the chlorobenzene, the N, N-dimethylformamide and the dimethyl sulfoxide; the photosensitizer is Ru (bpy)₃Cl₂、Ir(ppy)₃、Ir(bpy)(ppy)₂PF₆、Eosin Y、Na₂-Eosin Y and one of acridinium salt (II), said reaction formula (I) and acridinium salt (II) being as follows:

wherein:

R¹represents hydrogen, phenyl containing fluorine, chlorine, bromine, methyl, methoxy, trifluoromethyl, nitro substituent, thienyl, pyridyl;

R²represents phenyl, phenyl thienyl and pyridyl containing fluorine, chlorine, bromine, methyl, methoxy, trifluoromethyl and nitro substituents;

R³represents cyclopropyl, methyl, ethyl, phenyl containing fluoro, chloro, bromo, methyl, methoxy, trifluoromethyl, nitro substituents, thienyl, pyridyl;

R⁴represents methyl, phenyl;

x represents BF₄、ClO₄、PF₆。

2. The process for the photocatalytic synthesis of thiazole heterocycles according to claim 1, wherein the photosensitizer is an acridinium salt, wherein R is⁴Is phenyl, X represents BF₄。

3. The process for the photocatalytic synthesis of thiazole heterocyclic compounds according to claim 1, characterized in that the amount of said photosensitizer is 1-10 mol% with respect to the amount of thioamide.

4. The process for the photocatalytic synthesis of thiazole heterocycles according to claim 1, wherein the solvent is 1, 2-dichloroethane; or a mixed solvent of 1, 2-dichloroethane and acetonitrile, wherein the mixing volume ratio is 1:1-5: 1.

5. The photocatalytic synthesis method of thiazole heterocyclic compounds according to claim 1, characterized in that the ratio of the amount of thioamide to phenylacetylene is 1:2-2: 1.

6. The photocatalytic synthesis method for a thiazole heterocyclic compound according to claim 1, characterized in that the time for slowly dropping the thioamide with a syringe pump is 0 to 3 hours.

7. The photocatalytic synthesis method for a thiazole heterocyclic compound according to claim 1, characterized in that the blue light irradiation time is 10 to 24 hours.

Technical Field

The invention relates to the field of organic synthesis, in particular to a method for synthesizing a thiazole heterocyclic compound by photocatalysis.

Background

Thiazoles, as a basic structural heterocycle, have diverse biological activities and are widely used in drug molecule design ((a) z.jin, nat.prod.rep.,2013,30, 869; (b) d.davyt and g.serra, mar.drugs.,2010,8, 2755). The traditional methods for synthesizing thiazole heterocycles mainly comprise the following steps: cyclizing thioamides with phenylacetylene to synthesize thiazoles (Green chem.,2016,18,1455.) with the promotion of more than equivalent of NBS; thioamides are coupled with alpha-alkynols under the catalysis of silver to generate thiazoles (org.biomol.chem.,2010,8, 3259); the 2-aminothiazole is synthesized by the cascade reaction of ethylene azide and thiocyanate under the catalysis of transition metal palladium or copper ((a) org.Lett.2015,17, 4698-4801, (b) org.Lett.2018,20, 4819-4823); under the action of electrocatalysis, the oxidation cyclization reaction of isothiocyanate and amine synthesizes 2-aminobenzothiazole compounds (Green. chem.,2017,19, 2092.). The above methods have respective limitations such as difficulty in preparation of the substrate and narrow applicability, large environmental pollution, and the like. Therefore, the development of a novel method for synthesizing thiazole heterocyclic compounds with high efficiency, environmental protection and green color is necessary.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for synthesizing a thiazole heterocyclic compound by photocatalysis. The method is green and environment-friendly, is simple to operate, does not need other added oxidants and transition metals, takes green visible light as energy, and has high practical value for industrial production of thiazole.

The technical scheme for realizing the purpose of the invention is as follows:

the method for synthesizing the thiazole heterocyclic compound by photocatalysis is different from the prior art in that an alkyne raw material in a reaction general formula (I) is added with a photosensitizer without any other oxidant and transition metal, the alkyne raw material is stirred in a solvent while being irradiated by blue light, and thioamide is injected by an injection pump and is added into the solvent, so that the thiazole heterocyclic compound shown in the general formula can be obtained, wherein the solvent is one of acetonitrile, 1, 2-dichloroethane, chlorobenzene, N-dimethylformamide and dimethyl sulfoxide or a mixture of the acetonitrile, the 1, 2-dichloroethane, the chlorobenzene, the N, N-dimethylformamide and the dimethyl sulfoxide; the photosensitizer is Ru (bpy)₃Cl₂、Ir(ppy)₃、Ir(bpy)(ppy)₂PF₆、Eosin Y、Na₂-Eosin Y and one of acridinium salt (II), said reaction formula (I) and acridinium salt (II) being as follows:

wherein:

R¹represents hydrogen, phenyl containing fluorine, chlorine, bromine, methyl, methoxy, trifluoromethyl, nitro substituent, thienyl, pyridyl;

R²represents phenyl, phenyl thienyl and pyridyl containing fluorine, chlorine, bromine, methyl, methoxy, trifluoromethyl and nitro substituents;

R³represents cyclopropyl, methyl, ethyl, phenyl containing fluoro, chloro, bromo, methyl, methoxy, trifluoromethyl, nitro substituents, thienyl, pyridyl;

R⁴represents methyl, phenyl;

x represents BF₄、ClO₄、PF₆。

Preferably, the photosensitizer is an acridinium salt, wherein R is⁴Is phenyl, X represents BF₄。

Preferably, the amount of photosensitizer is 1-10 mol% relative to the amount of thioamide.

Preferably, the solvent is 1, 2-dichloroethane; or a mixed solvent of 1, 2-dichloroethane and acetonitrile, wherein the mixing volume ratio is 1:1-5: 1.

Preferably, the ratio of the amount of thioamide to phenylacetylene is 1:2 to 2: 1.

Preferably, the thioamide is slowly added dropwise by using a syringe pump for 0 to 3 hours.

Preferably, the blue light irradiation time is 10 to 24 hours.

The method is green and environment-friendly, is simple to operate, does not need other added oxidants and transition metals, takes green visible light as energy, and has high practical value for industrial production of thiazole.

Detailed Description

The invention will now be further illustrated, but is not intended to be limited, by the following examples: