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Preparation method of benzimidazole compound based on o-phenylenediamine cyclization

A technology of o-phenylenediamine and benzimidazole is applied in the field of preparation of pharmaceutical and chemical intermediates, and can solve the problems of high reaction temperature, complex reaction system and the like

Active Publication Date: 2014-07-09
DALIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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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 [see (a) Yang, D.; Fu, H.; Hu, L.; Jiang ,Y.;Zhao,Y.J.Org.Chem.2009,74,8719–8725.(b) Peng,J.;Ye,M.;Zong,C.;Hu,F.;Feng,L. .;Wang,Y.;Chen,C.J.Org.Chem.2011,76,716–719.]

Method used

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  • Preparation method of benzimidazole compound based on o-phenylenediamine cyclization
  • Preparation method of benzimidazole compound based on o-phenylenediamine cyclization
  • Preparation method of benzimidazole compound based on o-phenylenediamine cyclization

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] Embodiment 1: the synthesis of 2-methylbenzimidazole (3a)

[0030]

[0031] Accurately weigh o-phenylenediamine (54.0mg, 0.5mmol), acetylacetone (50.1mg, 0.5mmol) and benzoic acid (3.1mg, 0.025mmol), and add them to a 25mL Schlenk bottle in turn, add ethanol (5.0mL ), placed in a 20°C 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-methylbenzimidazole was 88%. 1 H NMR (400MHz, d 6 -DMSO)δ2.50(s,3H),7.12(dd,J=3.2,6.0Hz,2H),7.55(d,J=3.2Hz,1H),7.56(d,J=3.2Hz,1H), 9.25(s,1H),; 13 C NMR (100MHz, d 6 -DMSO) δ14.7, 114.3, 121.1, 139.0, 151.5.

Embodiment 2

[0032] Embodiment 2: the synthesis of 2-ethylbenzimidazole (3b)

[0033]

[0034] Accurately weigh o-phenylenediamine (54.0mg, 0.5mmol), 3,5-diheptanone (256.0mg, 2.0mmol) and benzoic acid (30.5mg, 0.25mmol), and add them to a 25mL Schlenk bottle in turn, Add 1,4-dioxane (3.0 mL) and place in an oil bath at 150° 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-ethylbenzimidazole was 65%. 1 H NMR (400MHz, CDCl 3 )δ1.45(t,J=7.6Hz,3H),3.03(q,J=7.5Hz,2H),7.21(dd,J=2.8,5.6Hz,2H),7.56(d,J=2.8Hz, 2H),11.49(s,1H); 13 C NMR (100MHz, CDCl 3 )δ12.9, 23.0, 114.9, 122.4, 138.9, 157.2.

Embodiment 3

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

[0036]

[0037] Accurately weigh 4-chloro-o-phenylenediamine (71.0mg, 0.5mmol), 3,5-diheptanone (64.0mg, 0.5mmol) and p-toluenesulfonic acid (9.5mg, 0.05mmol), and add them to 25mL Toluene (4.0 mL) was added to a 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-chlorobenzimidazole was 95%. 1 H NMR (400MHz, d 6 -DMSO)δ1.30(t,J=7.5Hz,3H),2.82(q,J=7.5Hz,2H),7.12(d,J=8.2Hz,1H),7.46(bs,2H),12.39( s,1H); 13 C NMR (100MHz, d 6 -DMSO) δ12.1, 22.1, 110.6, 112.0, 117.6, 119.3, 121.3, 125.4, 157.8.

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Abstract

The invention belongs to the field of fine chemistry and relates to an improved synthesis method of a benzimidazole compound and a related chemical technology. The synthesis method is characterized by comprising the step of with o-phenylenediamine and 1, 3-dicarbonyl compound as raw materials, synthesizing the benzimidazole compound under the catalysis of protonic acid. The invention mainly provides a novel synthesis method of the benzimidazole compound. The method has the advantages of mild reaction conditions, simple step, easily-obtained raw materials, good functional group compatibility and the like. Benzimidazole is an important biological active group and is widely applied in the field of pharmacy, and therefore, the preparation method has relatively high use value as well as social and economic benefits.

Description

technical field [0001] The invention relates to a preparation method of pharmaceutical and chemical intermediates, in particular to a preparation method of benzimidazole compounds. Background technique [0002] Benzimidazoles are an important class of biologically active molecules or intermediates in organic synthesis, and have a very wide range of applications in many fields. About the synthesis of benzimidazole compound, adopt following two kinds of methods usually: [0003] (1) Condensation reaction of o-benzenediamine compounds with carboxylic acids or aldehydes [0004] [0005] The reaction conditions of this method are very harsh, such as the need for strong acid, high temperature reaction conditions, or strong oxidant, and the raw material aldehyde is not easy to prepare and store [see: (a) Chhanda, M.; Pradip, K.T.Tetrahedron Lett.2008,49,6237 –6240. (b) Suleman, M.I.; Vinod, K.M.; Sisir, K.M. Tetrahedron Lett. 2013, 54, 579–583.]. [0006] (2) Copper-catalyze...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D235/08C07D235/18
CPCC07D235/08C07D235/18
Inventor 于晓强包明冯秀娟周晓玉穆罕默德谢里夫马祐
Owner DALIAN UNIV OF TECH
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