Silver Mediated Banert Cascade with Carbon Nucleophiles

Area of Science:

• Organic Chemistry
• Synthetic Chemistry

Background:

• The Banert cascade offers a route to complex nitrogen-containing heterocycles.
• Developing efficient methods for carbon-carbon bond formation is crucial in organic synthesis.

Purpose of the Study:

• To investigate the promotion of the Banert cascade by silver salts.
• To explore the interception of the triazafulvene intermediate with various carbon nucleophiles.
• To establish a correlation between nucleophile reactivity and reaction efficiency.

Main Methods:

• Utilizing silver salts to catalyze the Banert cascade of propargylic azides.
• Reacting the in-situ generated triazafulvene intermediate with diverse carbon nucleophiles, including indoles and other electron-rich heterocycles.
• Employing the Mayr nucleophilicity parameter (N) to quantify and correlate nucleophile reactivity with reaction outcomes.

Main Results:

• Successful promotion of the Banert cascade using simple silver salts.
• Demonstrated interception of the triazafulvene intermediate with over 25 examples of indoles and other heterocycles, achieving yields up to 92%.
• Established a clear correlation between the Mayr nucleophilicity parameter (N) and reaction efficiency, enabling predictable Csp-Csp and Csp-Csp bond formation.

Conclusions:

• Silver-promoted Banert cascade provides a versatile method for synthesizing functionalized heterocycles.
• The reaction's efficiency is predictable based on the nucleophilicity of the carbon source.
• This methodology facilitates the formation of C-C bonds using structurally diverse nucleophiles under mild conditions.