Acta Chimica Sinica ›› 2014, Vol. 72 ›› Issue (5): 595-601.DOI: 10.6023/A14020123 Previous Articles     Next Articles



耿浩兵a, 陈珊珊a, 孙玺a, 张袖丽a, 王磊b   

  1. a 安徽农业大学 化学系 合肥 230036;
    b 淮北师范大学 化学系 淮北 235000
  • 投稿日期:2014-02-21 发布日期:2014-04-15
  • 通讯作者: 张袖丽,王磊;
  • 基金资助:

    项目受国家自然科学基金(Nos. 21372095,21172092)和安徽省教育厅自然科学重点项目(No. KJ2013A122)资助.

Copper-Catalyzed Tandem Etherification Reactions of 2-(2,2-Dibromovinyl)phenol Derivatives with Phenols

Geng Haobinga, Chen Shanshana, Sun Xia, Zhang Xiulia, Wang Leib   

  1. a Department of Chemistry, Anhui Agricultural University, Hefei 230036;
    b Department of Chemistry, Huaibei Normal University, Huaibei 235000
  • Received:2014-02-21 Published:2014-04-15
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Nos. 21372095, 21172092) and Natural Key Project of Education Department, Anhui (No. KJ2013A122).

In this paper, copper-catalyzed tandem etherification reactions of 2-(2,2-dibromovinyl)phenol derivatives with phenols was developed. In the presence of copper acetate as catalyst and cesium carbonate as base, 2-(2,2-dibromovinyl)-phenol derivatives reacted with phenols in N,N-dimethyl formamide to generate the corresponding 2-phenoxybenzofurans in good yields in one-pot via tandem etherification reactions under ligand-free reaction conditions. Many reaction parameters including bases, copper salts and solvents have been investigated. By screening of bases in the reaction, we found that cesium carbonate is the best one among the tested bases. Experiments shown that strong bases and weak bases, such as potassium hydroxide, potassium t-butoxide, potassium acetate and sodium acetate are unfavorable for this reaction. Some common copper catalysts were examined, and the results indicated that copper acetate exhibits the highest reactivity in the reaction. For this reaction, a divalent copper salt is better than a monovalent copper salt. However, CuO and Cu2O gave the poor yield of the product. The solvent also plays a very important role in the reaction. We found that the optimum solvent is N,N-dimethyl formamide (DMF). Dimethyl sulfoxide, N,N-dimethylacetamide, and N-methylpyrrolidone also afforded good product yield. The further investigation revealed that the reaction temperature was one of the factors affecting the yield of the reaction. Scope of the substrate was studied and 24 new 2-aryloxybenzofuran compounds were synthesized in good yields. 2-(4-tert-Butylphenoxy)-5-chlorobenzofuran has the highest reaction yield in 94%. 4-(Benzofuran-2-yloxy)benzonitrile has the lower yield. Phenol containing an electron-withdrawing group on the benzene ring is difficult to perform the reaction. On the other hand, when an electron-donating group is introduced to 2-(2,2-dibromovinyl)phenol, such as 5-methoxy-, or 4-t-butyl-2-(2,2-dibromovinyl)phenol, the reaction was failed under the present reaction conditions. This method has several advantages including commercial availability of starting materials, simple operation, easy purification of products, and in the absence of ligand. This tandem reaction has the potential applications. It is important to note that the biological activity of the obtained 2-aryloxybenzofuran compounds will be further investigated and will be reported in due course.

Key words: 2-(2,2-dibromovinyl)phenol, phenols, 2-phenoxybenzofuran, diaryl ether, tandem reaction