Preparation method of benzothiazole compound based on aminothiophenol cyclization

A technology of o-aminothiophenol and benzothiazole, which is applied in the field of preparation of pharmaceutical and chemical intermediates, and can solve problems such as high reaction temperature and complex reaction system

Active Publication Date: 2014-03-26
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] The reaction system of this method is more complicated, as not only need copper salt catalyst, also need additives such as ligand, alkali, and reaction temperature is higher [referring to (a) W.R.Bowman, H.Heaney, P.H.G.Smith Tetrahedron, 1982,23,5093 .(b) E.A. Jaseer, D.J.C. Prasad, A. Dandapat, G. Sekar, Tetrahedron, 2010, 51, 5009.

Method used

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  • Preparation method of benzothiazole compound based on aminothiophenol cyclization
  • Preparation method of benzothiazole compound based on aminothiophenol cyclization
  • Preparation method of benzothiazole compound based on aminothiophenol cyclization

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Example 1: Synthesis of 2-methylbenzothiazole (3a)

[0030]

[0031] Accurately weigh o-aminothiophenol (62.5mg, 0.5mmol), acetylacetone (50.1mg, 0.5mmol) and benzoic acid (0.6mg, 0.005mmol), add them to a 25mL Schlenk bottle in sequence, and place at 20°C React in an oil bath for 24h. After the reaction was completed, the solvent was removed under reduced pressure, and petroleum ether / ethyl acetate was used as the eluent to separate through a silica gel column. The yield of 2-methylbenzothiazole was 92%. 1 H NMR (400MHz, CDCl 3 )δ2.78(s,3H)7.27-7.30(m,1H),7.37-7.41(m,1H),7.76(d,J=8.0Hz,1H),7.91(d,J=8.0Hz,1H) ; 13 C NMR (100MHz, CDCl 3 )δ17.7, 119.0, 119.9, 122.3, 123.5, 133.2, 150.9, 164.5.

Embodiment 2

[0032] Embodiment 2: Synthesis of 2-ethylbenzothiazole (3b)

[0033]

[0034] Accurately weigh o-aminothiophenol (62.5mg, 0.5mmol), 3,5-diheptanone (256.0mg, 2.0mmol) and benzoic acid (6.1mg, 0.05mmol), and add them to a 25mL Schlenk bottle in sequence , added 1,4-dioxane (3.0 mL), and placed in an oil bath at 200° C. for 36 h. After the reaction was completed, the solvent was removed under reduced pressure, and petroleum ether / ethyl acetate was used as the eluent to separate through a silica gel column. The yield of 2-ethylbenzothiazole was 90%. 1 H NMR (400MHz, CDCl 3 )δ1.45(t,J=7.6Hz,3H),3.13(q,J=7.6Hz,2H),7.31(dd,J=7.6,8.0Hz,1H),7.42(dd,J=7.6,8.0 Hz,1H),7.81(d,J=8.0Hz,1H),7.97(d,J=8.0Hz,1H); 13 C NMR (100MHz, CDCl 3 )δ13.7, 27.7, 121.4, 122.4, 124.5, 125.8, 135.0, 153.2, 173.4.

Embodiment 3

[0035] Embodiment 3: Synthesis of 2-ethyl-5-chlorobenzothiazole (3c)

[0036]

[0037] Accurately weigh 4-chloro-o-aminothiophenol (79.5mg, 0.5mmol), 3,5-diheptanone (64.0mg, 0.5mmol) and p-toluenesulfonic acid (9.5mg, 0.05mmol), and add them to Toluene (4.0 mL) was added into a 25 mL Schlenk bottle, and placed in an oil bath at 60° C. for 24 h. After the reaction was completed, the solvent was removed under reduced pressure, and petroleum ether / ethyl acetate was used as the eluent to separate through a silica gel column. The yield of 2-ethyl-5-chlorobenzothiazole was 85%. 1 H NMR (400MHz, CDCl 3 )δ1.45(t,J=7.6Hz,3H),3.13(q,J=7.6Hz,2H),7.29(d,J=8.4Hz,1H)7.70(d,J=8.4Hz,1H), 7.93(s,1H); 13 C NMR (100MHz, CDCl 3 )δ13.9, 28.1, 122.4, 122.6, 125.3, 132.1, 133.6, 154.4, 175.8.

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Abstract

The invention belongs to the field of fine chemical engineering, and relates to a synthesis method of a benzothiazole compound and a related chemical technology. The method is characterized in that aminothiophenol and a 1, 3-dicarbonyl compound are used as raw materials, and the benzothiazole compound is synthesized under catalysis of protonic acid. The invention mainly aims to provide a novel method for synthesizing the benzothiazole compound. The method has the advantages that the reaction condition is mild, the method steps are simple, the raw materials are easy to obtain, the functional group compatibility is good and the like. Benzothiazole is an important biological active group and has a very wide application in the pharmacy field, so that the method has greater use values and social and economical benefits.

Description

technical field [0001] The invention relates to a preparation method of pharmaceutical and chemical intermediates, especially a preparation method of benzothiazole compounds. Background technique [0002] Benzothiazole compounds are a class of important biologically active molecules and intermediates in organic synthesis, and have a very wide range of applications in many fields. Regarding the synthesis of benzothiazole compounds, the following two methods are usually adopted: [0003] (1) Condensation reaction of o-aminothiophenolic compounds with carboxylic acids or aldehydes [0004] [0005] The reaction conditions of this method are very harsh, as need strong acid, high temperature reaction conditions, or need strong oxidizing agent [referring to: (a) H.Sharghi, O.Asemani Synthetic Communications, 2009,39,860.(b) X.Wen, J.E.Bakali, R. Deprez-Poulain, B. Deprez. Tetrahedron, 2012, 53, 2440.] [0006] (2) Copper-catalyzed C–S bond cross-coupling reaction [0007] ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D277/64
CPCC07D277/64
Inventor 于晓强包明冯秀娟周晓玉
Owner DALIAN UNIV OF TECH
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