A Lactone-Enabled Approach to Metronidazole-Based Scaffolds.

Area of Science:

• Medicinal Chemistry
• Organic Synthesis
• Computational Chemistry

Background:

• Metronidazole is a key antimicrobial agent.
• Developing novel metronidazole derivatives is crucial for combating resistance.
• Nitroimidazole scaffolds offer diverse synthetic possibilities.

Purpose of the Study:

• To develop a scaffold-divergent synthetic approach for metronidazole analogs.
• To investigate the stability of N1-hydroxyethyl nitroimidazole-2-carboxylic acid.
• To establish a practical route to novel oxadiazole and amide derivatives.

Main Methods:

• Scaffold-divergent synthesis of nitroimidazole compounds.
• Characterization of N1-hydroxyethyl nitroimidazole-2-carboxylic acid and its derivatives.
• Density functional theory (DFT) calculations to probe reaction mechanisms.

Main Results:

• N1-hydroxyethyl nitroimidazole-2-carboxylic acid was found to undergo rapid decarboxylation.
• A stable lactone (compound 8) was synthesized and validated as a key intermediate.
• The lactone enabled efficient access to oxadiazole and amide derivatives.
• DFT calculations confirmed a low-barrier decarboxylation pathway for the unstable acid.

Conclusions:

• The instability of N1-hydroxyethyl nitroimidazole-2-carboxylic acid is attributed to facile decarboxylation.
• A novel lactone intermediate provides a stable and versatile platform for synthesizing diverse metronidazole-based compounds.
• This approach expands the synthetic utility of nitroimidazoles for drug discovery.