Post-Synthetic Modification of Oligonucleotides via Orthogonal Amidation and Copper Catalyzed Cycloaddition Reactions

Area of Science:

• Oligonucleotide chemistry
• Medicinal chemistry
• Bioconjugation

Background:

• Post-synthetic modification of oligonucleotides is crucial for developing therapeutic agents.
• Existing methods often lack efficiency or versatility.
• The 2'-position of nucleosides offers a valuable site for modification.

Purpose of the Study:

• To develop an efficient and versatile multicomponent orthogonal protocol for post-synthetic oligonucleotide modification.
• To utilize readily available nucleoside scaffolds for streamlined synthesis.
• To introduce chemical diversity into oligonucleotides for enhanced therapeutic potential.

Main Methods:

• Development of a multicomponent orthogonal protocol using 2'- O-methyl ester and 2'- O-propargyl nucleoside scaffolds.
• Amidation of methyl esters with primary amines in the presence of 2'-propargyl groups.
• Copper-catalyzed cycloaddition (Click chemistry) of 2'-propargyl groups with azides (e.g., GalNAc-azide).
• Application to the synthesis of small interfering RNA (siRNA) with multiple conjugates.
• Computational modeling to assess the impact of 2'-substitutions.

Main Results:

• Successful implementation of an efficient post-synthetic modification strategy.
• Generation of siRNA molecules containing both amide and triazole linkages.
• Demonstration of the ability to introduce multiple conjugates onto oligonucleotides.
• Computational insights into the effects of 2'-position substitutions on oligonucleotide properties.

Conclusions:

• The developed protocol provides a powerful and rapid method for post-oligomerization modification.
• This technique significantly enhances the ability to introduce diversity into oligonucleotide design.
• The methodology is suitable for generating complex oligonucleotide conjugates, such as modified siRNA.