Microwave-Assisted Synthesis of Quinoxalines in PEG-400

Abstract

A rapid and efficient procedure for the synthesis of quinoxaline derivatives has been achieved by condensation of aryl-1,2-diamines with 1,2-dicarbonyl compounds catalyzed by polyethylene glycol under CEM-focused microwave-irradiation conditions.

Keywords:

• Microwave
• polyethylene glycol
• quinoxaline derivatives

ACKNOWLEDGMENTS

The work was supported by the Natural Science Foundation of China (Grant Nos. 20272047 and 20572086), the Gansu Natural Science Foundation of China (No. 0308RJZA-100), and the Key Laboratory of Eco-environment-Related Polymer Material (Northwest Normal University), Ministry of the Education of China.

Notes

^a Reaction conditions: 4-methylbenzene-1,2-diamine (2.0 mmol), benzil (2.0 mmol), and catalyst irradiating under CEM focused microwave for 3 min at 200 W and 120 °C.

^b Isolated yield.

^a Reaction conditions: 4-methylbenzene-1,2-diamine (2.0 mmol), benzil (2.0 mmol), and PEG (0.3 mmol) irradiating under focused microwaves.

^b Isolated yield.

^c Reactions were performed with an improved reflux microwave oven.

^d Conventional heating was used, and the reaction was stirred in an oil bath at 120 °C.

^a All reactions were conducted in the same conditions: amines (2 mmol), ketones (2 mmol), PEG (0.3 mmol), P = 200 W if both the substrates are solid or P = 10 W if one of the substrates is liquid, at 120 °C for the appropriate time.

^b Isolated yields.