Azolopyrimidines and pyrimidoquinazolines from 4‐chloropyrimidines

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 disulphide and nitrous acid, respectively. The reaction of IIb,c with phenylhydrazine afforded directly the 5‐amino‐4,6‐diphenyl‐6 H ‐2‐substitutedpyrazolo[3,4‐ d ]pyrimidines VIa,b . The 4‐chloro derivative IIa reacted with antrhanilic acid to form the 5‐cyano‐2,4‐diphenyl‐6‐( o ‐carboxyphenylamino)pyrimidine VIII , which could be cyclised into the 4‐cyano‐1,3‐diphenyl‐10 H ‐pyrimido[6,1‐ b ]quinazolin‐10‐one IX by heating with acetic anhydride.