Synthesis of 5-polyfluoroalkyl-4-(p-tolyl-sulfonyl)pyrazoles and 4-polyfluoroalkyl-5-(p-tolylsulfonyl)pyrimidines from 1-dimethylamino-2-(p- tolylsulfonyl)-polyfluoro-1-alken-3-ones

1-Dimethylamino-2-(p-tolylsulfonyl)polyfluoro-1-alken-3-ones were obtained from hydrates of 3,3,3-trifluoro-1-(p-tolylsulfonyl)-2-propanone and 3,3,4,4,5,5-hexafluoro-1-(p-tolylsulfonyl)-2-pentanone under conditions of the Vilsmeier-Haack-Arnold reaction. The analogous reaction of 3,3-difluoro-1-(p- tolylsulfonyl)-2-propanone hydrate leads to 3-chloro-1-dimethylamino-4,4- difluoro-2-(p-tolylsulfonyl)-1,3-butadiene. The feasibility of using 1-dimethylamino-2-(p-tolylsulfonyl)-polyfluoro-1-alken-3-ones in reactions with nitrogen binucleophiles has been demonstrated for the regioselective synthesis of pyrazoles and pyrimidines. The structure of 1-phenyl-4-(p-tolylsulfonyl)-5- trifluoromethyl-1H-pyrazole was confirmed by X-ray diffraction structural analysis.