Ring transformations of 1,3,4-oxadiazol-2(3H)-one derivatives into 1-amino and 1,3-diamino-2,4-imidazolidinedione (hydantoin) derivatives

Some ethyl 5-aryl(or benzyl)-2-oxo-1,3,4-oxadiazole-3(2H)-acetates were prepared and treated with ammonia, primary amines or hydrazine to give 1-amino-2,4-imidazolidinedione or 1,3-diamino-2,4-imidazolidinedione derivatives. The 1,3-bis(benzylideneamino)-,2,4-imidazolidinedione was obtained by reacting ethyl bromoacetate with the 1,5-dibenzylidenecarbonohydrazide sodium salt