The synthesis of new 2-arylnaphtho[2’,3’:4,5]thieno[2,3-d][1,3]pyrimidine-4,5,10(3Н)-triones was carried out by the interaction of 2-aryl-4H-naphtho[2',3':4,5]thieno[2,3-d][1,3]oxazine-4,5,10-triones and ammonia in ethanol with the subsequent alkaline hydrolysis as one-pot reaction.