QD72 : Synthesis of 1, 2 disubstituted pyrrolo[2,3-b]quinoxalines By Sonogashira coupling reaction
Thesis > Central Library of Shahrood University > Chemistry > MSc > 2010
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Abstarct: The quinoxaline nucleus is present in many pharmaceutical agents exhibiting a broad spectrum of biological activities such as antiviral, antiglucoma, and anticancer activities.
In this work efficent synthesis of 2-acetyl/ 2-formyl-N-substituted pyrrolo[2,3-b]quinoxalines (123 a-j) through palladium catalyzed heteroannulation is reported. The reaction of 2,3-dichloroquinoxaline (15) with varius primarty alkylamines in refluxing acetonitril affords 2-alkylamino-3-chloroquinoxalines (121 a-g) in high yields.
When compounds (121 a-g) was treated with acetylenic alcohols (122 a-b) and morpholine in the presence of bis(triphenylphosphine)palladium chloride and cuprous iodide at 70ºC, new drivatives of 2-acetyl/ 2-formyl-N-substituted pyrrolo[2,3-b]quinoxalines (123 a-j) were obtained in good to high yields. The reaction was carried out under an argon atmosphere and morpholine was used both as a solvent and a baxse.
In the proposed mechanism for this reaction, the Pd(0) is formed in situ from the added catalyst. The structure of products were stablished from spectroscopic data abtained.
In conclusion, the described method for the synthesis of 2-acetyl/2-formyl-N-substituted pyrrolo[2,3-b]quinoxalines is an easy and one-pot procedure wich lead to high yields of product and can be extended to the synthesis of other heterocyclic compounds.
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