A N-nitroso moiety can be used for the activation of chloropyrimidines toward a nucleophilic substitution reaction with amines. The subsequent treatment of the obtained products with aq H₂SO₄ can lead to either N-denitrosation to obtain 4,6-pyrimidinediamines or to a Fischer–Hepp type rearrangement to obtain 5-nitroso-4,6-pyrimidinediamines. It was found that the outcome of the reaction strongly depends on the structure of the pyrimidines. Activation of the pyrimidine ring by three groups with a positive mesomeric effect is crucial for the intramolecular nitroso group migration.

The first example of catalyst-free tandem acetalization/5-exo-dig cyclization reactions of 6-phenylethynylpyrimidine-5-carbaldehydes is presented. Efficient novel synthesis of 5,7-dihydrofuro[3,4-d]pyrimidine core is described.