Azide‐Modified Nucleosides as Versatile Tools for Bioorthogonal Labeling and Functionalization

Azide‐modified nucleosides are important building blocks for RNA and DNA functionalization by click chemistry based on azide‐alkyne cycloaddition. This has put demand on synthetic chemistry to develop approaches for the preparation of azide‐modified nucleoside derivatives. We review here the available methods for the synthesis of various nucleosides decorated with azido groups at the sugar residue or nucleobase, their incorporation into oligonucleotides and cellular RNAs, and their application in azide‐alkyne cycloadditions for labelling and functionalization. This review aims to give a concise overview about the available synthetic approaches for preparation of various azide‐modified nucleosides. Furthermore, we highlight interesting and versatile strategies for the incorporation of azido functionalities into oligonucleotides and cellular RNAs, as well as their application in azide‐alkyne cycloadditions.