Synthesis of polyfluorodibenz[b,f][1,4]oxazepines by the cyclization of 2-[(polyfluorobenzylidene)amino]phenols

Thermolysis of 2-[(polyfluorobenzylidene)amino]phenols in ethanol in the presence of triethylamine affords the corresponding fluorinated dibenz[b,f][1,4]oxazepines in moderate to high yields. The structures of 2-[(2,3,4,5,6-pentafluorobenzylidene)amino]phenol and 1,2,3,4-tetrafluorodibenzo[b,f][1,4]oxazepine have been determined by single-crystal X-ray diffraction.