An Efficient Synthesis of Thiazolo and Thiadiazolo Quinoxaline Derivatives in Ionic Liquid

B Prasanna,Y Jagannadham,B Srinivas,Sumangala Rao

doi:10.1155/2012/865414

Abstract

A series of 3-substitutedphenyl-1-thia-tetrazopentaleno[1,2-b] naphthalene4(a-d)and 2-substitutedphenyl-1-thia-pentazopentaleno[1,2-b] naphthalene5(a-d)were synthesizedvia., the reaction of 2-aminothiazoles2(a-d)and 2-aminothiadiazoles3(a-d)with 2,3-dichloro quinoxaline1in ionic liquid without using any catalyst. This protocol has the advantages of easier workup, milder reaction conditions, high yields, and environmentally benign procedure over traditional methods. The synthesized compounds4(a-d)and5(a-d)tested for their anti-fungal activity and these compounds were characterized by IR, NMR and Mass spectral analysis.

Highlights

Compounds containing the quinoxaline nucleus exhibit abroad spectrum of biological activity such as, anti-viral[1], antiinflammatory, antiprotozoal[2], antihelminthic[3], anticancer[4], antimalarial[5], and antidepressant activities[6]
Quinoxalines are used in the synthesis of organic semiconductors, dyes[9], and electroluminescent materials[10]
Choosing an appropriate solvent is of crucial importance for the successful organic synthesis, Room temperature ionic liquids, especially those based on 1-alkyl-3methylimidazoliumcations have shown great promise as an attractive alternative to conventional organic solvents and more attention has been currently focused on organic reactions prompted by ionic liquids[20]

Summary

Introduction

Compounds containing the quinoxaline nucleus exhibit abroad spectrum of biological activity such as, anti-viral[1], antiinflammatory, antiprotozoal[2], antihelminthic[3], anticancer[4], antimalarial[5], and antidepressant activities[6]. Organic compounds bearing thiazolopyrimidines and pyridothiazolo quinoxaline nuclei were found to possess potent anticancer activities[16]. 1H NMR (300 MHz) spectra recorded in DMSO-d6 on a Bruker AVANCE 300 instrument with the TMS as an internal standard. A dry 50 mL flask was charged with 2, 3-dichloroquinoxaline[17,18 1] (1 mmol) and substituted 2-aminothiazoles 2(a-d) (1mmol)/2-aminothiadiazoles 3(a-d) (1 mmol) and ionic liquid [bmim] BF4 (2 mL).

Results

Conclusion