Ultrasound promoted facile one pot synthesis of highly substituted pyran derivatives catalyzed by silica-coated magnetic NiFe2O4 nanoparticle-supported H-14[NaP5W30O110] under mild conditions

Silica-coated magnetic NiFe2O4 nanoparticle-supported Preyssler heteropolyacid (H-14[NaP5W30O110]) catalyzed efficiently the synthesis of highly substituted pyran derivatives under ultrasonic irradiation at room temperature in ethanol. In comparison with conventional methods, our protocol is convenient and offers several advantages, such as shorter reaction times, higher yields, milder conditions and environmental friendliness. The catalyst can be recovered by a simple external magnet and used four times without a significant loss of catalytic activity.