Fast RNA conjugations on solid phase by strain-promoted cycloadditions

Abstract

Strain promoted cycloaddition is presented as a tool for RNA conjugation on the solid phase; RNA-cyclooctyne conjugates are prepared by cycloaddition to both azide (strain-promoted azide-alkyne cycloaddition, SPAAC) and nitrile oxide dipoles (strain-promoted nitrile oxide-alkyne cycloaddition, SPNOAC). The conjugation is compatible with 2′-OMe blocks and with 2′-O-TBDMS protection on the ribose moieties of the sugar. Nitrile oxide dipoles are found to be more reactive click partners than azides. The conjugation proceeds within 10 min in aqueous solvents, at room temperature without any metal catalyst and tolerates dipoles of varying steric bulk and electronic demands, including pyrenyl, coumarin and dabcyl derivatives.

Huisgen-based conjugation of water-soluble porphyrins to deprotected sugars: towards mild strategies for the labelling of glycans

“…42 Although it did not represent an issue in the present work, the presence of the copper ion is certainly a caveat for any CuAACbased labelling strategy to be carried out in biological environment: we anticipate that the new porphyrins reported here will be equally reactive under copper-free conditions, 43 which has already been successfully applied to cyclooctyne-functionalised carbohydrate substrates. 44 The application of this approach to more complex carbohydrates is the object of current studies in our laboratories.…”

Chemoselective Modification of Vinyl DNA by Triazolinediones

“…[15] At ambient temperatures,t hese reactions exhibit sluggish kinetics with second-order rate constants ranging from 10 À5 to 10 À1 m À1 s À1 . [16] Much faster reaction rates can be observed in photoclick, [17] strain-promoted nitrile-oxide-alkyne cycloaddition, [18] and strain-promoted inverse-electron-demand Diels-Alder reactions, [19] but these approaches require the introduction of bulky modifications onto the nucleotides that can interfere with their metabolism. [20] Thed evelopment of new bioconjugation reactions that utilize small, non-interfering bioorthogonal functional groups therefore remains ahigh priority (Figure 1).…”

Chemical Synthesis of Mono‐ and Bis‐Labeled Pre‐MicroRNAs

“…Elegant strategies were employed to achieve multiple labeling of short DNAs, for example through distinct protecting groups on the alkyne function,25 or through combined solid‐ and solution‐phase click chemistry 26. The subsequent introduction of Cu I ‐stabilizing ligands27, 28 or of activated cycloaddition partners29 rendered these protocols efficient also for RNA. This procedure was first employed for solution phase labeling of RNAs,27, 30–33 and was then adapted to solid phase conjugation of small molecules to short interfering RNAs (siRNA) with the aim to improve their targeting properties 34.…”