Abstract Guanidine reacts with chalkone 1 a, 4-methylchalkone 1 b and 4′-methylchalkone 1 c resp. to yield mixtures of pyrimidinamines 2 a, 3 b and 3 c (= 3 b) resp. with (2: 1)- condensates A, B and C resp. The structures of the compounds AC (which a priori could be dihydropyrimidopyrimidines 4 ac or 5 ac or 6 ac) are elucidated. NMR-investigations show that the salts AC· HCl must be symmetrically substituted pyrimidopyrimidinyliumchlorides ...
