Abstract 5-Cyano-3, 4-dihydro-6-phenyl-2-substitutedpyrimidin-4-ones 1a-c reacted with phosphorus oxychloride to give the corresponding 4-chloropyrimidine derivatives IIa-c. Compounds IIa-c reacted with aniline and hydrazine to yield the 4-anilino, IIIa, e, and 4- hydrazino, IIIb-d derivatives. The 4-hydrazino analogues IIIb, c could be converted into the triazolo [4, 3-c] and tetrazolo [4, 5-c] pyrimidines IV and V by the action of carbon ...