Synthesis of 2‐Perfluoroalkylazuleno[2,1‐d]pyrimidin‐4(3H)‐ones via Brønsted Acid‐Mediated Intramolecular Cyclization and Transformation into Pyrimidines.

Bronsted acid-mediated intramolecular cyclization of 2-amidoazulene derivatives, prepared by the reaction of 1-cyano-2-aminoazulene derivatives with perfluoroalkyl acid anhydrides, resulted in the formation of 2-perfluoroalkylazuleno[2,1-d]pyrimidin-4(3H)-ones. Heating of these products in phosphoryl chloride led to 4-chloro-2-perfluoroalkylazuleno[2,1-d]pyrimidines. We also evaluated the reactivity of these pyrimidin-4(3H)-ones and pyrimidine derivatives toward the electrophilic and nucleophilic substitution reactions, revealing that a variety of functional groups can be incorporated into these derivatives. The NMR studies, NICS calculations, and single-crystal X-ray structure analyses revealed structural features including the bond-length alternation of the azuleno[2,1-d]pyrimidin-4(3H)-ones and pyrimidine derivatives.