DNA with Branched Internal Side Chains: Synthesis of 5-Tripropargylamine-dU and Conjugation by an Azide-Alkyne Double Click Reaction
✍ Scribed by Venkata Ramana Sirivolu; Padmaja Chittepu; Frank Seela
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 377 KB
- Volume
- 9
- Category
- Article
- ISSN
- 1439-4227
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✦ Synopsis
Abstract
5‐Tripropargylamine‐2′‐deoxyuridine (1 a) containing two terminal triple bonds was synthesized by a Pd‐assisted Sonogashira cross‐coupling reaction and was subsequently converted into the corresponding phosphoramidite building block (9) and employed in solid‐phase oligonucleotide synthesis. T~m~ experiments demonstrate that the presence of covalently attached branched tripropargylamine residues has a positive effect on the base pair stability. The two terminal CC bonds of modified DNA were functionalized by means of Cu^I^‐mediated 1,3‐dipolar cycloaddition reactions (click chemistry) with azides such as 3‐azido‐7‐hydroxycoumarin or 3′‐azido‐3′‐deoxythymidine (AZT) both in solution and on solid support. In particular, with the nonfluorescent 3‐azido‐7‐hydroxycoumarin a strongly fluorescent oligonucleotide bis‐dye conjugate was generated. For comparison, the N(3)‐propargylated 2′‐deoxyuridine 2 was prepared from 2′‐deoxyuridine and propargyl bromide and incorporated into DNA. The two terminal triple bonds of 1 a allow the simultaneous post‐modification of DNA by two reporter molecules and can be applied to almost any azido derivatives (oligonucleotides, proteins, polysaccharides etc.) including those forming dendrimeric side chains.