Photochemical transformations of 5-perfluoroalkenyl uracils

Photochemical behavior of 1,3-dimethyl-5-trifluorovinyluracil 1 has been studied in polar, nucleophilic solvents (water and anhydrous methanol). Photoirradiation of 1 with UV light (λ > 300 nm) provides additional insight on previously suggested mechanism of phototransformations. Electrocyclization leading to cyclobutene intermediate 3 is a primary reaction; next addition of nucleophile (molecule of methanol or water) occurs, giving access to products.