Microwave Irradiation for Accelerating Synthesis of 5,6-Diphenylimidazo[1,2-a]pyrimidines Based on Isoflavones

Abstract

Microwave irradiation was used to accelerate the cyclocondensation of isoflavones with 2-aminoimidazole to synthesize 5,6-diphenylimidazo[1,2-a]pyrimidines. A series of 17 new compounds were characterized by Fourier transform infrared, NMR, and elemental analysis. 5-(2-Hydroxyl-4-isopropoxyphenyl)-6-phenylimidazo-[1,2-a]pyrimidine was determined by x-ray diffraction. A variety of substrates can participate in the process with good yields and purities, making this methodology suitable for library synthesis in drug discovery.

Keywords:

• Cyclocondensation
• imidazo[1,2-a]pyrimidine
• isoflavone
• microwave irradiation

ACKNOWLEDGMENTS

This research was supported by the National Natural Science Foundation of China (No. 20772076) and the Science and Technology Key Project of Xi'an of Shaanxi Province (No. CXY08019).

Notes

^a Isolated yield after silica chromatography.

^a All reactions were carried out in the appropriate solvent (8 mL) using ipriflavone (1a, 1 mmol), 2-aminoimidazole sulfate (2), and base until complete disappearance of 1a (microwave irradiation for 0.5 h, MeOH, EtOH at boiling point and n-BuOH, glycol, and DMSO at 100 °C, output 240 W, TLC check).

^b Isolated yield after silica chromatography.

^c No reaction.