Synthesis of polyfluorinated 4-phenyl-3,4-dihydroquinolin-2-ones and quinolin-2-ones via superacidic activation of N-(polyfluorophenyl)cinnamamides

The cyclization reactions of a series of polyfluorocinnamanilides in triflic acid (CF3SO3H) yield 4-phenyl-3,4-dihydroquinolin-2-ones, which include a polyfluorinated benzene moiety as a part of the quinoline scaffold. These compounds undergo dehydrophenylation in the presence of AlCl3 to give the corresponding polyfluoroquinolin-2-ones which are converted into polyfluorinated 2-chloroquinolines on treatment with POCl3. A mechanism for the cyclization reaction presuming the intermediacy of a superelectrophilic O,C-diprotonated form of the starting material is suggested.