Ultrasonic irradiated synthesis and herbicidal activities of 5,7-disubstituted-2-(substituted pyridine-3-formylimino)-2H-1,2,4-thiadiazolo[2,3-a]pyrimidine derivatives

Eight new substituted-pyridine-3-formylimino-2H-1,2,4-thiadiazolo[2,3-a] derivatives containing substituted pyrimidine ring were synthesized in good yield under ultrasonic irradiation (USI). The structures of all newly synthesized compounds were elucidated and confirmed by IR, H-1 NMR and elemental analysis. The target compounds have been screened for activity against a number of monocotyledones and dicotyledones. The preliminary herbicidal tests show that some of the target compounds have better inhibitory activities against weeds.