Synthesis of Triazole‐Nucleoside Phosphoramidites and Their Use in Solid‐Phase Oligonucleotide Synthesis

Abstract

Triazole-backbone oligonucleotides are macromolecules that have one or more triazole units that are acting as a backbone mimic. Triazoles within the backbone have been used within oligonucleotides for a variety of applications. This unit describes the preparation and synthesis of two triazole-nucleoside phosphoramidites [uracil-triazole-uracil (UtU) and cytosine-triazole-uracil (CtU)] based on a PNA-like scaffold, and their incorporation within oligonucleotides.

Synthesis of folate-labeled siRNAs from a folate derivative phosphoramidite

“…We first prepared a dimethoxytrityl (DMT)-protected triazole linker, as illustrated in Scheme 1. Compounds A and B were synthesized according to previously published protocols, 18,19 and were conjugated via a copper-catalyzed azide-alkyne cycloaddition (CuAAC) to afford compound C. To prepare the folate derivative phosphoramidite 3 ≠ , we treated folic acid with trifluoroacetic anhydride (TFAA), as previously described in the literature, 20 to produce the pyrofolic acid derivative 1. This compound was subsequently reacted with compound C to yield a novel triazole-linked folate derivative (Scheme 2).…”

“…1 H NMR (400 MHz, DMSO-d6) δ ppm 1.99-2.07 (m, 1 H), 2.41-2.60 (overlap, 3 H), 4.73 (dd, 1 H), 5.76 (s, 2 H), 7.64 (s, 4 H), 8.68 (s, 1 H). 19 Synthesis of compound 2. Compound C (0.5 g, 0.94 mmol) was dissolved in anhydrous DMF (20 mL) under argon.…”

“…The resulting residue was purified using silica gel chromatography, eluting from 5 to 60% MeOH/CH 2 Cl 2 with 5% triethylamine to yield compound 2 as brown crystals (0.70 g, 74%). 19 Synthesis of compound 3 ≠ . To a flame-dried round-bottom flask was added a solution of compound 2 (0.2 g, 0.196 mmol) in anhydrous 1 : 1 DCM and THF (10 mL) and triethylamine (0.16 mL, 1.18 mmol), under an argon atmosphere.…”

“…The resulting crystals were collected by filtration and dried in vacuo to yield compound 3 ≠ , which was immediately used for solid-phase oligonucleotide synthesis (0.19 g, 79%). 19…”

Molecular bionics – engineering biomaterials at the molecular level using biological principles

“…Solid-phase synthesis has been optimised to obtain peptides, oligonucleotides and other molecules in an efficient fashion [232][233][234]. Everything starts from an aminoacid or nucleotide which is immobilised on a suitable solid phase (e.g., polystyrene).…”