Abstract
A convenient and mild synthesis of 5-bromo-N4-substituted-1-(β-D-arabinofuranosyl)cytosine and 5-bromo-O4-methyl-1-(β-D-arabinofuranosyl)pyrimidin-2(1H)-one derivatives by selective oxyfunctionalization of the corresponding 4-thionucleosides with 3,3-dimethyldioxirane is reported. The cytotoxicity and the antiviral activity against parainfluenza 1 (Sendai virus) of all new synthesized products are also reported.