Fluorescent derivatives of nucleosides

Abstract Fluorescence spectra of formycin anhydronucleosides 5,6,8 and of N‐dimethylaminomethylene ribonucleosides 1b, 2, 3a‐3c and 4 in aqueous solution at 5‐7 × 10−5 M are reported. Compounds 5 and 6 exhibit a very strong fluorescence emission, ca. 4 and 2 times more intense than that of formycin (1a) accompanied by a bathochromic shift of the emission maximum. Anhydronucleoside 8 also has an increased fluorescence intensity over the parent nucleoside 7. The level of fluorescence emission is lower in 7 and 8 than in 1a, 5 or 6. Introduction of N‐dimethylaminomethylene group into 1a (compound 1b) caused a decrease in the fluorescence intensity relative to 1a but a bathochromic shift of the emission maximum. In other instances (compounds 2, 3a‐3c, 4) the introduction of N‐dimethylaminomethylene group led also to fluorescent derivatives. This effect is most pronounced with 2, whereas the fluorescence intensity of the rest of the group (3a‐3c and 4) is much lower. Compounds 3c and 4 exhibit, however, a profound bathochromic shift in the fluorescence emission maximum relative to 2, 3a or 3b. A possible relationship of the fluorescence emission to the base conformation in formycin and potential use of N‐dimethylaminomethylene nucleoside and nucleotide derivatives as fluorescent probes are discussed. J. Heterocyclic Chem., 14, 135 (1977).