Abstract: As a continuation to our projects of searching for new anticancer and antiviral agents, the series of novel 1-(2'-alkylthioethoxy)methyl uracils have been synthesized in overall yields of 70.4%_74.9% in three steps from uracil, and they have been smoothly oxidized into corresponding sulfoxides in yields of 88.5%_94.4% by NaIO₄ in ethanol/water. Corresponding sulfones were obtained in yields of 86.2% _93.5% from sulfides and sulfoxides by means of 30% H₂O₂ /DEAD(diethyl diazodicarboxylate) as oxidation reagent in methanol or THF. All the new compounds have been characterized by ¹H NMR, IRspectrum and elemental analysis. The literature procedure of synthesizing the key intermediate(1,4 bistrimethylsilyluracil) was improved by hexamethyldisiylazane(HMDS)/trimethyl chloride(TMSCl) as substituent of HMDS/(NH₄)₂SO₄, and reaction time was shortened so much from 12 h to 3 h in new procedure. The experimental results indicated that the conversion of sulfides and sulfoxides to the corresponding sulfones was very slow and in low yields(42.5% and 47.3%), when only 30% H₂O₂ was used as the oxidation reagent. After addition of DEADinto the reaction mixture, the reaction could be considerably accelerated, and conversion rates of the reaction were raised (86.2%_93.5%). The anticancer and antiviral activities of the compounds 4, 5, 6 are being testing.

Key words: Uracil derivatives, Sulfides, Oxidation, Sulfoxides, Sulfones