TIPS-5-Ethynyl-dU-CE Phosphoramidite can be used instead of the 5-Ethynyl-dU-CE Phosphoramidite under standard conditions for solid phase synthesis. The protecting group reduces the risk of side products. The oligo is deprotected after the synthesis leading to ethynyl modified oligonucleotides. The usage of TIPS-5-Ethynyl-dU-CEP in combination with other alkyne modified phosphoramidites (e.g. 5-Ethynyl-dU-CEP or C8-Alkyne-dU-CEP) enables the possibility to create Oligos which can be modified by Click Chemistry consecutively. Therefore, firstly the unprotected alkyne is clicked and after deprotection of TIPS the second click can be performed.

LITERATURE

Ethynyl Side Chain Hydration during Synthesis and Workup of “Clickable” Oligonucleotides: Bypassing Acetyl Group Formation by Triisopropylsilyl Protection, S. A. Ingale et al., 2013, J. Org. Chem., Vol. 78, p. 11271–11282.

https://doi.org/10.1021/jo401780u

Nucleosides And Oligonucleotides With Diynyl Side Chains: The Huisgen-Sharpless Cycloaddition “Click Reaction” Performed On Dna And Their Constituents, F. Seela et al., 2007, Nucleosides, Nucleotides & Nucleic Acids, Vol. 26, p. 597–601.

https://doi.org/10.1080/15257770701490308

Postsynthetic DNA Modification through the Copper-Catalyzed Azide–Alkyne Cycloaddition Reaction, P. M. E. Gramlich et al., 2008, Angew. Chemie Int. Ed., Vol. 47, p. 8350–8358.

https://doi.org/10.1002/anie.200802077

Efficiency and Fidelity in a Click-Chemistry Route to Triazole Dendrimers by the Copper(I)-Catalyzed Ligation of Azides and Alkynes, P. Wu et al., 2004, Angew. Chemie Int. Ed., Vol. 43, p. 3928–3932.

https://doi.org/10.1002/anie.200454078

Peptidotriazoles on Solid Phase:  [1,2,3]-Triazoles by Regiospecific Copper(I)-Catalyzed 1,3-Dipolar Cycloadditions of Terminal Alkynes to Azides, C. W. Tornøe et al., 2002, J. Org. Chem., Vol. 67, p. 3057–3064.

https://doi.org/10.1021/jo011148j

Click Chemistry: Diverse Chemical Function from a Few Good Reactions, H. C. Kolb et al., 2001, Angew. Chemie Int. Ed., Vol. 40, p. 2004–2021.

https://doi.org/10.1002/1521-3773(20010601)40:11<2004::AID-ANIE2004>3.0.CO;2-5