Simple and Efficient Method for Synthesis of 3-Cyano-6,7-diarylpyrazolo[1,5-a]pyrimidine from Isoflavones

Abstract

A series of 3-cyano-6,7-diarylpyrazolo[1,5-a]pyrimidines have been synthesized directly from the 5-amino-4-cyano-1H-pyrazole and isoflavones. The target compound was obtained by a condensation reaction. Structures of compounds were demonstrated by Fourier transform infrared, NMR, and elemental analysis. The advantages of this synthetic route are simple operation, mild reaction conditions, and good yields.

GRAPHICAL ABSTRACT

Keywords:

• Condensation
• 3-cyano-6,7-diarylpyrazolo[1,5-a]pyrimidine
• isoflavones

ACKNOWLEDGMENTS

This research was supported by the National Natural Science Foundation of China (No: 20772076) and Science and Innovation Funds of Graduate Programs of Shaanxi Normal University (No. 2008CXS029).

Notes

^a All reactions were carried out with isoflavone 1a (2 mmol), 5-amino-4-cyano-1H-pyrazole 2, and different kinds of bases until the formation in appropriate solvents (20 mL) was completed as monitored by TLC (24 h, refluxing).

^b Isolated yield based on isoflavone.

^c Reactions with EtOH, MeOH, and THF as solvent were carried out under the boiling point.

^d The reaction with DMF as solvent was carried at 100 °C.

^a Reaction conditions: 1 (2 mmol), 2 (2.6 mmol), NaOCH₃ (6 mmol), 70 °C.

^b Isolated yield after silica-gel chromatography.