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Method for synthesizing benzothiazole derivatives

A synthetic method, benzothiazole technology, applied in the field of organic synthesis, can solve the problems of uneconomical and environmental protection

Inactive Publication Date: 2016-06-08
SHANGHAI INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Due to the presence of benzyl mercaptan in the reaction process, it is not economical and environmentally friendly

Method used

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  • Method for synthesizing benzothiazole derivatives
  • Method for synthesizing benzothiazole derivatives
  • Method for synthesizing benzothiazole derivatives

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] 1. Add N-oxalyl-substituted 2-(4-methoxy-benzylthio)-4-bromo-aniline (0.2mmol), trifluoroacetic acid (0.1ml) and thiourea to a 50ml sealed tube. (0.2mmol). The reaction was heated at 80°C, and the reaction was detected by TLC. After the reaction was completed, saturated sodium bicarbonate solution was added to quench the reaction. It was extracted three times with 30 ml of n-hexane, and the upper organic phase was evaporated to dryness to obtain 6-bromo-2-ethyl acetate benzothiazole with a yield of 95%. Then add 1mol / L sodium hydroxide solution (1ml), 4-bromo-2-fluoro-nitrobenzene (0.2mmol) to the lower aqueous phase, stir the reaction at room temperature, check the reaction by TLC, add 15ml after the reaction is complete Extraction with ethyl acetate, dry with anhydrous sodium sulfate, rotary evaporate the organic phase, and column chromatography (petroleum ether: ethyl acetate = 7:1) to obtain 4-bromo-2-(4-methoxy-benzylthio) -Nitrobenzene, the yield is 80%.

[0046] ...

Embodiment 2

[0049] 1. Add N-oxalyl substituted 2-(2-methoxy-benzylthio)-aniline (0.2mmol), trifluoroacetic acid (0.1ml) and thiourea (0.2mmol) to a 50ml sealed tube. . The reaction was heated at 80°C, and the reaction was detected by TLC. After the reaction was completed, saturated sodium bicarbonate solution was added to quench the reaction. It was extracted three times with 30 ml of n-hexane, and the upper organic phase was evaporated to dryness to obtain 2-ethyl acetate benzothiazole with a yield of 95%. Then add 1mol / L sodium hydroxide solution (1ml), 2-fluoro-nitrobenzene (0.2mmol) to the lower aqueous phase, stir the reaction at room temperature, TLC check the reaction, add 15ml of ethyl acetate after the reaction is complete Extraction, drying with anhydrous sodium sulfate, rotary evaporation of the organic phase, and column chromatography (petroleum ether: ethyl acetate = 7:1) to obtain 2-(2-methoxy-benzylthio)-nitrobenzene with a yield 78%.

[0050] 2. Add 2-(2-methoxy-benzylthio...

Embodiment 3

[0053] 1. Add N-benzoyl substituted 2-(4-methoxy-benzylthio)-6-methoxy-aniline (0.2mmol) and trifluoroacetic acid (0.1ml) to a 50ml sealed tube. And thiourea (0.2 mmol). The reaction was heated at 80°C, and the reaction was detected by TLC. After the reaction was completed, saturated sodium bicarbonate solution was added to quench the reaction. It was extracted three times with 30ml of n-hexane, and the upper organic phase was evaporated to dryness to obtain 4-bromo-2-phenylbenzothiazole with a yield of 95%. Then add 1mol / L sodium hydroxide solution (1ml), 6-methoxy-2-fluoro-nitrobenzene (0.2mmol) to the lower aqueous phase, stir the reaction at room temperature, check the reaction by TLC, and after the reaction is complete Add 15ml of ethyl acetate for extraction, dry with anhydrous sodium sulfate, evaporate the organic phase, and column chromatography (petroleum ether: ethyl acetate = 7:1) to obtain 6-methoxy-2-(4-methoxy- Benzylthio)-nitrobenzene, the yield was 82%.

[0054...

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Abstract

The invention discloses a method for synthesizing benzothiazole derivatives. Thiourea is used as a sulfur source, and the thiourea and o-fluoronitrobenzene derivatives are continuously converted into the benzothiazole derivatives by means of three-step conversion. The method includes enabling 2-benzylthio-benzamide derivatives to react to trifluoroacetic acid and the thiourea to obtain reaction products, extracting the reaction products by the aid of n-hexane, concentrating n-hexane layers to obtain the benzothiazole derivatives, and adding the o-fluoronitrobenzene derivatives and sodium hydroxide solution into lower-layer water phases to obtain 2-benzylthio-nitrobenzene derivatives; reducing tin dichloride to obtain 2-benzylthio-aminobenzene derivatives; ultimately acylating the 2-benzylthio-aminobenzene derivatives to obtain 2-benzylthio-substituted benzamide analogs. The method has the advantages of simplicity, environmental protection and low cost.

Description

Technical field [0001] The present invention relates to the technical field of organic synthesis, in particular to a method for synthesizing benzothiazole derivatives. Background technique [0002] Benzothiazole heterocycles are an important class of molecular building blocks, which are widely used in medicines, pesticides, and materials. Currently, there are several methods for constructing benzothiazole rings: [0003] (1) It constructs a benzothiazole ring by reacting o-aminothiophenol with aromatic aldehyde, carboxylic acid, acid chloride, or acetonitrile, and the reaction equation is shown in (a). [0004] [0005] Because the raw materials are thiophenol compounds, there will be uncomfortable odors during the experimental operation, and because there are not many types of thiophenols, the scope of application of this construction method is limited. [0006] (2) First vulcanize the ortho-activated benzamide, and then convert the thiobenzamide into a benzothiazole derivative unde...

Claims

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Application Information

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IPC IPC(8): C07D277/66C07D277/64
CPCC07D277/64C07D277/66
Inventor 殷燕周鸿刘希晨张恒
Owner SHANGHAI INST OF TECH
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