Tetrachloromaxamycins: Divergent Total Synthesis and Initial Assessments

Area of Science:

• Medicinal Chemistry
• Synthetic Organic Chemistry
• Molecular Biology

Background:

• Vancomycin is a critical antibiotic, but resistance is a growing threat.
• Modifying vancomycin's structure is a key strategy to overcome resistance.
• Developing novel synthetic routes for complex glycopeptides is essential.

Purpose of the Study:

• To develop a streamlined synthesis for modified vancomycins.
• To create novel tetrachlorovancomycin analogs with altered binding properties.
• To evaluate the antibacterial activity and mechanisms of action of new compounds.

Main Methods:

• Convergent synthesis of a late-stage thioamide intermediate.
• Stereochemical simplification using aryl chlorides.
• Protecting-group-free modifications of binding pocket and periphery.
• Simultaneous macrocyclizations of CD and DE ring systems.
• Preparation of novel maxamycin derivatives.

Main Results:

• A novel, efficient synthesis of tetrachlorovancomycin intermediates was achieved.
• Pocket-modified analogs ([Ψ[C(═S)NH]Tpg⁴]tetrachlorovancomycin, [Ψ[C(═N)NH]Tpg⁴]tetrachlorovancomycin, and [Ψ(CH₂NH)Tpg⁴]tetrachlorovancomycin) were synthesized.
• Compounds demonstrated dual d-Ala-d-Ala/d-Lac ligand binding, overcoming resistance.
• New maxamycin members exhibited synergistic mechanisms of action independent of native ligand binding.
• Antibacterial activity and pharmacokinetic assessments were reported.

Conclusions:

• The developed synthetic strategy enables efficient access to diverse vancomycin analogs.
• Modified vancomycins show promise in overcoming existing antibiotic resistance.
• Novel mechanisms of action broaden the potential of these compounds against resistant bacteria.