New series of 4,6-diheteroarylpyrimidine-2ـamines (4a-e) and (5a-c) were prepared by cyclization of particular chalcones (2) or (3) with guanidine nitrate in the presence of potassium hydroxide. Chalcones (2) and (3) were prepared by base-catalyzed Claisen-Schmidt condensation of heteroaryl aldehydes (1) with 2-acetyl-5-chlorothiophene and 3-acetyl-2,5-dichlorothiophene, respectively. All the newl...