MECHANISM OF CRISS-CROSS REACTION OF AROMATIC GLYOXALIMINES WITH POTASSIUM CYANATE AND THIOCYANATE

摘要

Aromatic 1,4-diazabuta-1,3-dienes(glyoxalimines)react with potassium cyanate and thiocyanate in ethereal acetic acid to give the corresponding4-acetoxy-5-(4-substitutedphenylamino)-3-(4-substituted phenyl)-imidazolidin-2-ones and perhydroimidazo[4,5-d]imidazol-2,5-dithiones,respectively.In order to learn more about the reaction mechanism,kinetic measurements have been carried out.It was found that the reaction involves a direct nucleophilic addition of thiocyanate anion to 1,4-diazabuta-1,3-diene,whereas the less nucleophilic cyanate anion requires acid catalysis.