Synthesis and tumour-localizing properties of [18F]-5-fluorocytosine-arabinoside and [18F]-5-fluorocyclocytidine

[¹⁸F]-5-fluorocytosine-arabinoside (2) and [¹⁸F]-5-fluorocyclocytidine (4) were prepared by reaction of [¹⁸F]-acetylhypofluorite with cytosine-arabinoside (1) or cyclocytidine (3) in acetic acid and were isolated in an overall radiochemical yield of 20% and 9%, respectively. The biodistribution of both radiopharmaceuticals was determined in melanoma bearing Syrian golden hamsters. It was found that 2 is a good tumour-localizing agent for pigmented and non-pigmented Greene melanoma.