Perhalogenated thiazoles. Their synthesis,reactions and mass spectra

The synthesis of six new mixed perhalogenaled thiazoles ane reported. Three of these contain a 2-fluoro substituent one of which includes the novel 5-bromo-4-chloro-2-fluorothiazole. The mass spectral fragmentation pattern of the perhalogenated thiazoles was used to elucidate the orientation of the halogen suhstituents. A novel halogen migration from carbon to nitrogen in the mass spectrum was observed for several of the perhalogenated thiazoles. Nucleophilie displacement of fluoride ion in 4,5-diehloro-2-flurothiazile ( 7 ) by cyano, hydroxyl and methoxyl unions and by diclhyl amine produced the respective 2-substituted dichlorothiazoles. The ease of electrophilic substitution on carbon in the polyhalogenated thiazoles was observed to be 2 > > 5 > 4. Sulfur tetrafluoride fluorinalion of 2-earboxy-4,5-dichlorothiazole, formed by lilhiation and eurbonation of tricblorolhiazole, yielded 4,5-dicbloro-2-trifluoromethylthiazole.