Novel and Versatile Reactions of Trifluoroamine Oxide:  A New Route to Polyfluorinated Ethers

A series of pyrimidine methyl and polyfluoroalkyl ethers were synthesized from the reactions of trifluoroamine oxide (1) with several 5-substituted uracils in the presence of tetrabutylammonium hydroxide and methanol, 2,2,2-trifluoroethanol (6), or 1H,1H-pentafluoropropanol (7). With 5-(trifluoromethyl)uracil (2), the new ethers formed were 5-fluoro-5-(trifluoromethyl)-6-methoxypyrimidine-2,4-dione (8), 5-fluoro-5-(trifluoromethyl)-6-(trifluoroethoxy)pyrimidine-2,4-dione (9), and 5-fluoro-5-(trifluoromethyl)-6-(1H,1H-pentafluoropropoxy)pyrimidine-2,4-dione (10). With 5-chlorouracil (3), the new ethers 5-chloro-5-fluoro-6-methoxypyrimidine-2,4-dione (11), 5-chloro-5-fluoro-6-(trifluoroethoxy)pyrimidine-2,4-dione (12), and 5-chloro-5-fluoro-6-(1H,1H-pentafluoropropoxy)pyrimidine-2,4-dione (13) were obtained. With 5-fluorouracil (4), the new ethers 5,5-difluoro-6-methoxypyrimidine-2,4-dione (14), 5,5-difluoro-6-(trifluoroethoxy)pyrimidine-2,4-dione (15) and 5,5 difluoro-6-(1H,1H-pentafluoropropoxy)pyrimidine-2,4-dione (16) were found. By reaction of 5-nitrouracil (5), the new ethers 5-nitro-5-fluoro-6 methoxypyrimidine-2,4-dione (17), 5-nitro-5-fluoro-6-(trifluoroethoxy)pyrimidine-2,4-dione (18), and 5-nitro-5-fluoro-6-(1H,1H-pentafluoropropoxy)pyrimidine-2,4-dione (19) were obtained. Each of the new compounds was characterized by using IR, ¹⁹F and ¹H NMR, and mass spectroscopy, and elemental analysis. A single-crystal X-ray diffraction study of 8 was helpful in confirming compound structure.