Despite their demand in chemical biology, a high-yielding and sustainable synthesis of Se-containing nucleosides has not yet been described. Previous work has established that 2-Se pyrimidine nucleosides can be accessed either from methylated sulfo-nucleosides or via selenation of isocytidine (Scheme 1). However, these chemical syntheses have several drawbacks, including the need for multi-step routes starting from a natural nucleoside, as well as an unfavorable atom economy and the extensive use of organic solvents.