[Synthetic study of nucleoside antibiotics]

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Synthetic Chemistry

Background:

• Nucleoside antibiotics possess complex structures and sensitive functionalities, posing significant synthetic challenges for organic chemists.
• Despite synthetic difficulties, these compounds are valuable drug candidates due to their diverse biological activities.
• Existing synthetic methods often struggle with the regioselectivity and mild conditions required for these complex molecules.

Purpose of the Study:

• To develop efficient synthetic strategies for complex nucleoside antibiotics.
• To explore the utility of samarium diiodide (SmI(2))-mediated aldol reactions in synthesizing these challenging molecules.
• To synthesize key structural components of caprazamycins for potential antibacterial drug development.

Main Methods:

• Utilized a samarium diiodide (SmI(2))-mediated aldol reaction employing alpha-phenylthioketones as enolate sources for synthesizing Herbicidin B and tunicaminyluracil.
• Achieved regioselective enolate generation and performed aldol reactions under near-neutral conditions.
• Developed a synthetic route for caprazol, involving beta-selective ribosylation and diazepanone construction via modified reductive amination.

Main Results:

• Successfully synthesized undecose nucleoside antibiotics Herbicidin B and fully protected tunicaminyluracil.
• Demonstrated the efficacy of the SmI(2)-mediated aldol reaction for complex nucleoside antibiotic synthesis.
• Established a synthetic pathway for caprazol, a key component of caprazamycins, enabling the creation of analogues.

Conclusions:

• The SmI(2)-mediated aldol reaction is a powerful tool for the synthesis of complex nucleoside antibiotics.
• The developed synthetic strategies provide access to key analogues for structure-activity relationship studies.
• This research paves the way for developing more effective antibacterial agents based on nucleoside antibiotic scaffolds.