Synthesis of 4‐(trihalomethyl)dipyrimidin‐2‐ylamines from β‐alkoxy‐α,β‐unsaturated trihalomethyl ketones

The synthesis of a novel series of twelve 4‐(trihalomethyl)dipyrimidin‐2‐ylamines, from the cyclo‐condensation reaction of 4‐(trichloromethyl)‐2‐guanidinopyrimidine, with β‐alkoxyvinyl trihalomethyl ketones, of general formula: X 3 C‐C(O)‐C(R 2 )=C(R 1 )‐OR, where: X = F, Cl; R = Me, Et, ‐(CH 2 ) 2 ‐, ‐(CH 2 ) 3 ‐; R 1 = H, Me; R 2 = H, Me, ‐(CH 2 ) 2 ‐, ‐(CH 2 ) 3 ‐, is reported. The reactions were carried out in acetonitrile under reflux for 16 hours, leading to the dipyrimidin‐2‐ylamines in 65‐90% yield. Depending on the substituents of the vinyl ketone, tetrahydropyrimidines or aromatic pyrimidine rings were obtained from the cyclization reaction. When X = Cl, elimination of the trichloromethyl group was observed during the cyclization step. The structure of 4‐(trihalomethyl)dipyrimidin‐2‐ylamines was studied in detail by 1 H‐, 13 C‐ and 2D‐nmr spectroscopy.