Synthesis and Properties of Fluorescent cyclo Sal Nucleotides Based on the Pyrimidine Nucleoside m 5 K and Its 2′,3′‐Dideoxy Analog dm 5 K

The synthesis of the fluorescent thymidine nucleoside analog 5‐methyl‐pyrimidin‐2‐one nucleoside 1 (m 5 K) and that of its 2′,3′‐dideoxy derivative 2 (dm 5 K) are described. Moreover, the conversion of 1 and 2 into the corresponding 3‐methyl‐ cyclo Sal‐phosphate triesters 11 and 12 or an enzyme‐cleavable prodrug 5‐acetoxymethylpropionate‐ cyclo Sal‐phosphate triester 13 , and the fluorescence and hydrolysis properties of these new lipophilic triesters are reported. Finally, the suitability of these cyclo Sal pronucleotides as probes is demonstrated in a cell‐extract hydrolysis experiment and a model study for cell uptake. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)