[Synthesis of Modified Nucleosides Using 4'-Carbon Radicals]

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Nucleoside Chemistry

Background:

• 4"-modified nucleosides are vital for antiviral drugs and oligonucleotide therapeutics.
• Current ionic synthesis methods for 4"-modified nucleosides have limitations including poor stereoselectivity and complex protection steps.
• Developing new synthetic strategies for 4"-modified nucleosides is essential.

Purpose of the Study:

• To review novel methods for generating 4"-carbon radicals as intermediates for synthesizing 4"-modified nucleosides.
• To highlight the advantages of radical-based approaches over traditional ionic methods.
• To demonstrate the facile synthesis of diverse 4"-modified nucleosides.

Main Methods:

• Generation of 4"-carbon radicals via radical deformylation involving β-fragmentation of a 4 ahydroxymethyl group.
• Generation of 4 ahydroxymethyl group-retaining 4 ahydrocarbon radicals using radical decarboxylation and 1,5-hydrogen atom transfer (1,5-HAT).

Main Results:

• Two novel methods for generating 4 ahydrocarbon radicals were summarized.
• These methods allow for rapid and facile generation of 4 ahydrocarbon radicals.
• Various 4 ahydro-modified nucleosides, including 2 ahydro,4 ahydro-bridged structures, were synthesized.

Conclusions:

• Radical-based methods offer a significant advancement in the synthesis of 4 ahydro-modified nucleosides.
• These new strategies overcome key drawbacks of existing ionic reaction pathways.
• The described methods provide efficient access to valuable nucleoside analogs for therapeutic applications.