NMR and UV studies of 4-thio-2'-deoxyuridine and its derivatives.

5-Substituted-4-thio-2'-deoxyuridine nucleosides have been chemically synthesized and studied by NMR and UV spectroscopy. The results have been analyzed and discussed in connection with the previous data. The imino proton signal and the carbon signal of the thiocarbonyl group in the 5-substituted-4-thio-2'-deoxyuridines were found to be at much lower field, offering a potential for monitoring these modified bases at the DNA level. All 4-thionucleosides have strong absorptions at around 340 nm and consequently would be useful as potential UVA-induced anticancer agents.