Ultrasound assisted dehydrogenation of 2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamides

► In the present work we will report on ultrasound-assisted thermal and thermal oxidation of 2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamides in the presence of tetrabutylammonium peroxydisulfate in acetonitrile. ► In this work, we have elucidated the effect of sonic waves on the shortening of reaction time and on decreasing the amount of the oxidant compared with thermal reactions. ► As we have also observed in our previous works, the nature of 4-substituent influences the time of oxidation. ► Due to decreasing of the electron-withdrawing nature of the amide groups compared to the carboethoxy and the acetyl groups, the rate of oxidation of the title compounds is comparatively faster.