CN109020966B - Method for preparing cosmetic additive 2- (benzofuran-2-yl) benzoxazole - Google Patents
Method for preparing cosmetic additive 2- (benzofuran-2-yl) benzoxazole Download PDFInfo
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- CN109020966B CN109020966B CN201811242681.7A CN201811242681A CN109020966B CN 109020966 B CN109020966 B CN 109020966B CN 201811242681 A CN201811242681 A CN 201811242681A CN 109020966 B CN109020966 B CN 109020966B
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- benzoxazole
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D413/00—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms
- C07D413/02—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms containing two hetero rings
- C07D413/04—Heterocyclic compounds containing two or more hetero rings, at least one ring having nitrogen and oxygen atoms as the only ring hetero atoms containing two hetero rings directly linked by a ring-member-to-ring-member bond
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- Heterocyclic Carbon Compounds Containing A Hetero Ring Having Nitrogen And Oxygen As The Only Ring Hetero Atoms (AREA)
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Abstract
The invention relates to the technical field of fine chemical engineering, and discloses a method for preparing a cosmetic additive 2- (benzofuran-2-yl) benzoxazole. The method comprises the following specific steps: benzoxazole and benzofuran-2-carboxylic acid are used as raw materials, nickel chloride is used as a catalyst, silver carbonate and 1, 3-bis (2, 6-diisopropylphenyl) imidazole chloride are used as additives, and the raw materials react in chlorobenzene at 160 ℃ for 20 hours to obtain the 2- (benzofuran-2-yl) benzoxazole. Compared with the prior art, the method is quick and simple, and the target product is directly constructed in one step. In addition, the carboxylic acid which is cheap and easy to store is used as a coupling reagent, so that the method has potential industrial value and is worthy of popularization and application.
Description
Technical Field
The invention belongs to the field of fine chemical engineering, and relates to a method for preparing a cosmetic additive 2- (benzofuran-2-yl) benzoxazole.
Background
In recent years, 2-substituted benzoxazole derivatives have been widely used in organic functional materials, natural products, drugs, etc. due to their unique biological and physical properties, and thus, research on such derivatives has been receiving much attention. 2- (benzofuran-2-yl) benzoxazole is an important cosmetic additive, is used for helping human skin to resist ultraviolet rays, and can prevent various damages caused by dust and radiation to the skin to play a role in protecting the skin. The literature reports the following three methods for synthesizing 2- (benzofuran-2-yl) benzoxazole:
the first method is to remove one molecule of hydrogen bromide from benzoxazole and 2-bromo-benzofuran to 2- (benzofuran-2-yl) benzoxazole under the action of bivalent palladium catalyst. The method has the disadvantages that expensive palladium catalysis is required, and hydrogen bromide waste gas generated in the reaction needs to be additionally treated.
In the second method, 2-chlorobenzoxazole and benzofuran are used as raw materials, and one molecule of hydrogen chloride is removed to 2- (benzofuran-2-yl) benzoxazole under the continuous action of an n-butyl lithium reagent and a divalent palladium catalyst. The method has the following defects: not only is a dangerous n-butyllithium reagent used, but also an expensive palladium catalyst and a corresponding phosphorus ligand are used, and the generated hydrogen chloride waste gas is additionally treated.
In the third method, benzoxazole and 2, 2-dibromo vinyl phenol are used as raw materials, and two molecules of hydrogen bromide are removed to obtain the 2- (benzofuran-2-yl) benzoxazole under the action of a copper catalyst. Although this method uses cheap and easily available copper as a catalyst, the reaction requires expensive raw material 2, 2-dibromovinylphenol, and the reaction produces a large amount of hydrogen bromide waste gas requiring additional treatment.
Therefore, the exploration and development of a simple, novel, easy-to-operate, highly practical and environmentally friendly synthetic route for 2- (benzofuran-2-yl) benzoxazole derivatives is one of the important tasks of chemists.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provide a method for synthesizing a 2- (benzofuran-2-yl) benzoxazole derivative, which has high practicability, simplicity, novelty, simple and convenient operation and environmental friendliness.
The reaction steps for synthesizing the 2- (benzofuran-2-yl) benzoxazole comprise: adding benzoxazole, benzofuran-2-carboxylic acid, nickel chloride, silver carbonate and 1, 3-bis (2, 6-diisopropylphenyl) imidazole chloride into a pressure-resistant tube containing a reaction solvent chlorobenzene in sequence, stirring vigorously at 150-170 ℃ for 18-22 hours, and after the reaction is finished, concentrating the reaction liquid and separating by column chromatography in sequence to obtain the 2- (benzofuran-2-yl) benzoxazole. The method is rapid and simple, uses cheap and easily-stored carboxylic acid as a coupling reagent to directly construct a target product in one step, and has potential industrial value.
In the invention, the solvent can be chlorobenzene or trifluorotoluene, and chlorobenzene is preferred.
The concentration of the reaction system in the present invention is 0.1 to 0.3 mol/l, preferably 0.2 mol/l.
In the invention, the mole ratio of benzoxazole, benzofuran-2-carboxylic acid, nickel chloride, silver carbonate and 1, 3-bis (2, 6-diisopropylphenyl) imidazole chloride is 1: 3: 0.1: 2.5: 0.2.
the reaction temperature in the invention is 150-170 ℃, preferably 160 ℃.
The reaction time in the invention is 18-22 hours, preferably 20 hours.
Detailed Description
The following examples will help illustrate the invention, but do not limit its scope.
Specific example 1:
benzoxazole (1mmol,0.12g), benzofuran-2-carboxylic acid (3mmol,0.49g), nickel chloride (0.1mmol,0.013g), silver carbonate (2.5mmol,0.69g), 1, 3-bis (2, 6-diisopropylphenyl) imidazolium chloride (0.2mmol,0.085g) and 5mL chlorobenzene were added in this order to a 50mL pressure resistant tube, the reaction temperature was controlled at 160 ℃ and the reaction was stirred vigorously for 20 hours. After the reaction, the reaction mixture was cooled to room temperature, and then concentration and column chromatography were carried out in this order to obtain 2- (benzofuran-2-yl) benzoxazole (0.153g, 65%).
The reaction involves the following equation:
specific example 2:
benzoxazole (1mmol,0.12g), benzofuran-2-carboxylic acid (3mmol,0.49g), nickel chloride (0.1mmol,0.013g), silver carbonate (2.5mmol,0.69g), 1, 3-bis (2, 6-diisopropylphenyl) imidazolium chloride (0.2mmol,0.085g) and 5mL of trifluorotoluene were added in this order to a 50mL pressure resistant tube, the reaction temperature was controlled at 160 ℃ and the reaction was stirred vigorously for 20 hours. After the reaction, the reaction mixture was cooled to room temperature, and then concentration and column chromatography were carried out in this order to obtain 2- (benzofuran-2-yl) benzoxazole (0.146g, 62%).
The foregoing describes alternative embodiments of the invention to teach those skilled in the art how to make and reproduce the invention. Some conventional technical aspects have been simplified and omitted for the purpose of teaching the inventive arrangements. Those skilled in the art will appreciate variations from this aspect that fall within the scope of the invention.
Claims (7)
1. A process for the preparation of a cosmetic additive 2- (benzofuran-2-yl) benzoxazole characterized in that: adding benzoxazole, benzofuran-2-carboxylic acid, nickel chloride, silver carbonate and 1, 3-bis (2, 6-diisopropylphenyl) imidazole chloride into an organic solvent, heating and stirring vigorously to react to obtain the 2- (benzofuran-2-yl) benzoxazole.
2. The method as claimed in claim 1, further comprising reduced pressure distillation after the reaction, column chromatography separation and collection of the target product.
3. The method of claim 1, wherein: the reaction temperature is 150-170 ℃.
4. The method of claim 1, wherein: the reaction time is 18-22 hours.
5. The method of claim 1, wherein: benzoxazole, benzofuran-2-carboxylic acid, nickel chloride, silver carbonate and 1, 3-bis (2, 6-diisopropylphenyl) imidazole chloride are added in a molar ratio of 1: 3: 0.1: 2.5: 0.2.
6. the method of claim 1, wherein: the organic solvent used in the reaction is chlorobenzene.
7. The method of claim 1, wherein: the concentration of the reaction system is 0.1-0.3 mol/L.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811242681.7A CN109020966B (en) | 2018-10-24 | 2018-10-24 | Method for preparing cosmetic additive 2- (benzofuran-2-yl) benzoxazole |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201811242681.7A CN109020966B (en) | 2018-10-24 | 2018-10-24 | Method for preparing cosmetic additive 2- (benzofuran-2-yl) benzoxazole |
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| CN109020966A CN109020966A (en) | 2018-12-18 |
| CN109020966B true CN109020966B (en) | 2020-02-14 |
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| CN201811242681.7A Active CN109020966B (en) | 2018-10-24 | 2018-10-24 | Method for preparing cosmetic additive 2- (benzofuran-2-yl) benzoxazole |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP6367121B2 (en) * | 2013-02-07 | 2018-08-01 | 国立大学法人名古屋大学 | Coupling method and method for producing aromatic group-substituted heterocyclic compound using the coupling method |
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2018
- 2018-10-24 CN CN201811242681.7A patent/CN109020966B/en active Active
Non-Patent Citations (2)
| Title |
|---|
| Cobalt-Catalyzed Decarboxylative C−H (Hetero)Arylation for the Synthesis of Arylheteroarenes and Unsymmetrical Biheteroaryls;Yanrong Li et al.;《Org. Lett.》;20171009;第19卷;第5589-5592页 * |
| Decarbonylative C.H Coupling of Azoles and Aryl Esters:Unprecedented Nickel Catalysis and Application to the Synthesis ofMuscoride A;Kazuma Amaike et al.;《J. Am. Chem. Soc.》;20120807;第134卷;第13573-13576页 * |
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