One-Step Efficient Synthesis of Pyrazolo[3,4-f]quinoline Derivatives Under Microwave Irradiation

Abstract

A series of new pyrazolo[3,4-f]quinoline derivatives were synthesized by multicomponent reactions of equimolar amounts of aromatic aldehydes 1, barbituric acids 2 (barbituric acid or 1,3-dimethyl barbituric acid), and 5-aminoindazole 3 in mixed solvent of glacial acetic acid and ethylene glycol (2:1, v/v) without catalyst under microwave irradiation. This one-pot protocol has the advantage of good yields (91–94%), simple workup procedure, and short reaction times (5–6 min).

Keywords:

• Microwave irradiation
• mixed solvent
• pyrazolo[3,4-f]quinoline

ACKNOWLEDGMENTS

We are grateful for the financial support from the National Science Foundation of China (Nos. 20372057 and 20672090), the Natural Science Foundation of the Jiangsu Province (No. BK2006033), and the Elite Foundation of the Jiangsu Province (No. 06-A-039).

Notes

^a Volume ratio.

^b Isolated yields.

^a Isolated yields.

^a Isolated yields.