Rapid microwave-enhanced synthesis of C5-alkynyl pyranonucleosides as novel cytotoxic antitumor agents.

A microwave-assisted, one-pot, coupling reaction for the synthesis of C5-alkynyl-uracil and cytosine glucopyranonucleosides has been developed. The reaction is carried out under standard Sonogashira coupling conditions from glucopyranonucleosides of 5-iodouracil or 5-iodocytosine and various terminal alkynes. All compounds were evaluated for their cytostatic and antiviral activity. The 5-phenylethynyluracil pyranonucleoside derivative 6a showed the most promising cytostatic activity (50% inhibitory concentration in the lower micromolar range). No meaningful antiviral activity was recorded.