Immobilized piperazine on the surface of graphene oxide as a heterogeneous bifunctional acid–base catalyst for the multicomponent synthesis of 2-amino-3-cyano-4H-chromenes,Green Chemistry

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Immobilized piperazine on the surface of graphene oxide as a heterogeneous bifunctional acid–base catalyst for the multicomponent synthesis of 2-amino-3-cyano-4H-chromenes
Green Chemistry ( IF 9.3 ) Pub Date : 2020-06-22 , DOI: 10.1039/d0gc01274b
Asma Khazaee _{1,

2,

3,

4,

5} , Roya Jahanshahi _{1,

2,

3,

4,

5} , Sara Sobhani _{1,

2,

3,

4,

5} , Jørgen Skibsted _{6,

7,

8,

9} , José Miguel Sansano _{10,

11,

12,

13,

14}

Affiliation

Immobilized piperazine on the surface of graphene oxide (piperazine-GO) is synthesized and characterized by different methods such as FT-IR, solid-state ²⁹Si{¹H} and ¹³C{¹H} CP/MAS NMR, elemental analysis, TGA, TEM, FE-SEM, XPS, and TPD. Subsequently, it is used as a heterogeneous bifunctional acid–base catalyst for the efficient multicomponent reaction of malononitrile, different active compounds containing enolizable C–H bonds and various aryl/alkyl aldehydes in aqueous ethanol. A wide variety of 2-amino-3-cyano-4H-chromenes are synthesized in the presence of this heterogeneous catalyst in good to high yields and with short reaction times. The catalyst is easily separated and reused for at least six times without significant loss of activity. The acidic nature of GO improves the catalytic activity of the supported piperazine and also provides heterogeneity to the catalyst. Use of aqueous ethanol as a green solvent, high turnover numbers (TON), facile catalyst recovery and reuse, simple work-up and generality of the method make this protocol an environmentally benign procedure for the synthesis of the title heterocycles.

中文翻译：

固定在氧化石墨烯表面上的哌嗪作为异质双官能酸碱催化剂，用于多组分合成2-氨基-3-氰基-4H-色烯

合成并固定在氧化石墨烯（哌嗪-GO）表面上的哌嗪可以通过不同的方法进行表征，例如FT-IR，固态²⁹ Si { ¹ H}和¹³ C { ¹ H} CP / MAS NMR，元素分析， TGA，TEM，FE-SEM，XPS和TPD。随后，它被用作多相双官能酸碱催化剂，用于丙二腈，含有可烯化CH键的不同活性化合物和乙醇水溶液中各种芳基/烷基醛的高效多组分反应。各种各样的2-氨基-3-氰基-4 H在该非均相催化剂的存在下以高产率至高产率和短反应时间合成二苯甲基苯并二氢萘。催化剂易于分离并重复使用至少六次，而活性没有明显损失。GO的酸性性质改善了负载的哌嗪的催化活性，并且还为催化剂提供了非均相性。使用乙醇水溶液作为绿色溶剂，高周转率（TON），简便的催化剂回收和再利用，简单的后处理方法以及方法的通用性，使得该方案成为合成标题杂环的环境友好的方法。

更新日期：2020-07-20

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