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Synthetic Communications
An International Journal for Rapid Communication of Synthetic Organic Chemistry
Volume 38, 2008 - Issue 19
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Original Articles

Efficient Synthesis of Quinoxaline Derivatives Catalyzed by p-Toluenesulfonic Acid Under Solvent-Free Conditions

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Pages 3329-3337 | Received 15 Jan 2008, Published online: 12 Sep 2008
 

Abstract

A series of quinoxaline derivatives were efficiently synthesized in excellent yields by the reaction of 1,2-diamines and 1,2-diketones with grinding catalyzed by p-toluenesulfonic acid under solvent-free conditions at room temperature. Compared with the classical synthetic method, this new method has the advantages of convenient manipulation and environmental friendliness.

ACKNOWLEDGMENTS

We are grateful to the Open-End Foundation of the Key Laboratory of Organic Synthesis for financial support.

Notes

a All reactions were performed at 1-mmol scale using 10 mol% of catalyst with grinding under solvent-free conditions.

b Isolated yields.

a All reactions were performed at 1-mmol scale using 10 mol% of p-TsOH with grinding at room temperature.

b Isolated yields.

a Method A: 1,2-diamine (1 mmol), 1,2-diketone (1 mmol), p-TsOH (0.1 mmol), grinding, solvent free, rt, purified by recrystallization from ethanol.

b Method B: 1,2-diamine (1 mmol), 1,2-diketone (1 mmol), 10 mol% of iodine in 0.5 mL of CH3CN, rt, purified by flash column chromatography.

c Method C: 1,2-diamine (10 mmol), 1,2-diketone (10 mmol), 10 mol% of iodine in 10 mL of DMSO, rt, purified by recrystallization from ethanol.

d Method D: 1,2-diamine (0.2 mmol), 1,2-diketone (0.2 mmol), 3 mL of 9:1 MeOH-HOAc, at 160 °C, purified by preparative LCMS.

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