Using Sodium Hydride and Potassium Carbonate as Bases in Synthesis of Substituted 2-Amino-4-aryl-7-propargyloxy-4H-chromene-3-carbonitriles

(E-pub Abstract Ahead of Print)

Author(s): Nguyen Dinh Thanh*, Do Son Hai, Vu Thi Ngoc Bich, Pham Thi Thu Hien, Nguyen Thi Ky Duyen, Nguyen Thi Hai Mai, Tran Thi Dung, Hoang Thi Kim Van, Vu Ngoc Toan, Duong Ngoc Toan, Le Hai Dang, Tran Thi Thanh Van.

Journal Name: Current Organic Synthesis

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Aims and Objective: 1-Alkynes are the important precursors for the CuAAC click chemistry. The hybrid of 1,2,3-triazole ring to the chromene ring and sugar moiety could bring some remarkable biological properties. Propargyl derivatives are usually used in the click chemistry. This article reported the synthesis of 2-amino-4-aryl-7-propargyloxy-4-aryl-4H-chromene-3-carbonitriles using propargyl bromide as alkylation agent. The use of potassium carbonate and sodium hydride as bases in the conversion of 2-amino-4-aryl-7-hydroxy-4-aryl-4H-chromene-3-carbonitriles into corresponding propargyl ethers in Williamson’s ether synthesis.

Materials and Method: The use of CTAB for synthesis of benzylidene malononitriles and anhydrous potassium carbonate as a catalyst in absolute ethanol in the synthesis of 2-amino-7-hydroxy-4H-chromene-3-carbonitriles. This is the efficient and simple synthetic methods. Propargyl ether compounds of these 4H-chromene-3-carbonitriles were obtained from the alkylation reaction by propargyl bromide. Two procedures were applied: K2CO3 as a base in acetone solvent (Procedure A) and NaH as a base in DMF solvent (Procedure B). The single-crystal X-ray structure of propargyl ether 5e has been study.

Results: The use of K2CO3 and NaH as bases in the Williamson’s ether synthesis from 2-amino-7-hydroxy-4H-chromene-3-carbonitriles showed that Procedure B was better route and gave the ethers in the higher yields. 2-Amino-4-aryl-7-propargyloxy-4-aryl-4H-chromene-3-carbonitriles were obtained from corresponding 7-hydroxy-4H-chromene-3-carbonitriles. Yields of ethers 5a-i were 70−89% and 80−96%, respectively in depending on the used procedures.

Conclusion: The described methods are the simple, clean and environmentally friendly alternatives for the preparation of 2-amino-4-aryl-7-hydroxy-4H-chromene-3-carbonitriles. The conditions for the transformation of these compounds into propargyl ethers were dried DMF as a solvent, NaH as a base and the reaction time of 2 h at the room temperature. A series of 2-amino-4-aryl-7-hydroxy-4-aryl-4H-chromene-3-carbonitriles were obtained based on investigated reaction condition.

Keywords: 4H-Chromene, multi-component reaction, propargyl ether, potassium carbonate, sodium hydride, Williamson’s ether synthesis

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(E-pub Abstract Ahead of Print)
DOI: 10.2174/1570179416666190104124652
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