Photochemical Trifluoromethylation of Some Aromatic and Heteroaromatic Compounds with Trifluoromethyl Bromide

The photochemical introduction of trifluoromethyl group with CF3Br in aromatic and heteroaromatic rings was investigated for 9 compounds. Naphthalene, anthracene, anisole, N,N-dimethylaniline, ferrocene, benzo[b]thiophene, isoquinoline, and N-methylpyrrole gave trifluoromethylated products in 6.5–100% yields. In one step from uracil, a pharmacologically important 5-trifluoromethyluracil can be synthesized by this method in 11% yield. Based on the mechanistic study carried out for the naphthalene–CF3Br–CH3CN system, the reaction is found to proceed via the electron transfer from an excited singlet state of naphthalene to CF3Br.