A new approach to pyrimidine-type heterocycles based on Petrenko–Kritschenko synthesis

new series of tetrahydropyrimidines were prepared by employing the Petrenko–Kritschenko reaction between 2-nitrobenzaldehyde and 1,3-dicarbonyl compounds in the presence of ammonium acetate at ambient temperature. The reaction afforded an unexpected heterocyclic skeleton instead of the usual piperidone ring. Physicochemical analyses including 1 H, 13 C NMR and HRMS were used to elucidate this structure. The stereochemistry was investigated by X-ray crystallography analysis and DFT calculations. The available results confirm the existence of an unusual structure containing two bulky groups at the cis position in the pyrimidine ring. Formation of such an exceptional structure is possible due to the π– π stacking stabilization of nitrophenyl groups.