Synthesis, mechanism and fluorescence properties of 8-(aryl)-3-beta-D-ribofuranosylimidazo[2,1-i]purine 5'-phosphate derivatives.

The synthesis of new fluorescent nucleotides is described. This synthesis comprises two parallel reactions, the Kornblum oxidation and imidazole formation, which lead to 8-(aryl)-3-beta-D-ribofuranosylimidazo[2,1-i]purine 5'-phosphates 2 from AMP or ATP. A detailed mechanism is proposed based on monitoring the reaction by 1H- and 13C-NMR spectroscopy, MS, FAB, HPLC, and pH meter. The spectral and fluorescent properties of the new derivatives at various pH values are described. Excitation and emission maxima for 3 were observed at 290 and 420 nm, respectively, in both basic and neutral media. In acidic media, the emission maximum shifted to 410 nm, however, the fluorescence intensity increased 1.5-fold. ATP analogues 2b and 3b exhibited relative stability regarding hydrolysis by type II ATPDase. Compound 3b is relatively chemically stable at pH 10.4 and 7.4.