An Entry of the Chemoselective Sulfo-Click Reaction into the Sphere of Nucleic Acids.

We report here the first example of a sulfo-click conjugation reaction to be applied to modified nucleosides. The reaction, which proceeds rapidly (k ∼ 2.0 × 10-1 M-1 s-1 at 25 °C) under aqueous biocompatible conditions in the ribo- and deoxyribonucleoside series, affords the corresponding conjugated products in excellent yields. Furthermore, we demonstrate the orthogonality of the reaction with the copper-catalyzed azide-alkyne click reaction (CuAAC) by performing a one-pot dual labeling of a nucleoside carrying two orthogonal azido groups.