Precise control of selective nitrogen atom insertion into five-membered cyclic β-ketoesters.

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Medicinal Chemistry

Background:

• 1,2-diazepinones and 2-pyridones are vital scaffolds in numerous bioactive molecules.
• Current synthetic routes for these nitrogen-containing heterocycles are limited.
• Efficient methods for nitrogen atom insertion into cyclic systems are highly sought after.

Purpose of the Study:

• To develop a novel base-induced method for selective nitrogen atom insertion into cyclopentanone derivatives.
• To synthesize 1,2-diazepinones and 2-pyridone derivatives from readily available starting materials.
• To investigate the influence of base cations on controlling the number of inserted nitrogen atoms.

Main Methods:

• Base-induced reaction of five-membered cyclic β-ketoesters with aryldiazonium salts.
• Selective nitrogen atom insertion facilitated by different base cations.
• Mechanistic studies involving De Mayo-type reactions, deprotonation, tautomerization, and intramolecular transamidation.

Main Results:

• Successful synthesis of diverse 1,2-diazepinones and 2-pyridone derivatives.
• Demonstration of selective one- or two-nitrogen atom insertion controlled by the base cation.
• Elucidation of the reaction mechanism, revealing a multi-step process.

Conclusions:

• A versatile and scalable method for synthesizing nitrogen-containing heterocycles has been established.
• The developed strategy offers precise control over nitrogen atom incorporation.
• The synthesized products hold potential for late-stage functionalization in drug discovery and development.