Pseudouridine (Psi) is the most abundant modified nucleosides in RNA and the only naturally occurring C-nucleoside. It is enzymatically generated in RNA and has variable functions that are not fully understood. Pseudouridine synthesis is enzyme catalyzed. Defects in these enzymes cause multisystem disorders because of a decrease in pseudouridine formation. On the other hand, it was shown that pseudouridine synthesis is upregulated under stress conditions in constitutive sites and new sites. The goal of this project is to synthesize a suitable radical precursor for pseudouridine to study the effect of oxidative stress on RNA. The data comparison between the effect of oxidative stress on pseudouridine and on other nucleosides possessing C-N glycosyl bonds would give valuable information about the function of pseudouridine.