Synthesis of bench-stable diarylmethylium tetrafluoroborates

Area of Science:

• Organic Chemistry
• Materials Science

Background:

• Carbenium ions are important reactive intermediates in organic synthesis.
• Developing stable carbenium ion derivatives is crucial for practical applications.

Purpose of the Study:

• To synthesize and characterize novel bench-stable nonsymmetric diarylcarbenium tetrafluoroborates.
• To investigate the stability of these compounds under various conditions.

Main Methods:

• Direct coupling of aryl (or heteroaryl) aldehydes and N-heteroarenes.
• Full characterization including X-ray crystallography and Nuclear Overhauser Effect (NOE) determination.

Main Results:

• A series of bench-stable nonsymmetric diarylcarbenium tetrafluoroborates were successfully isolated.
• These compounds demonstrated high stability in the presence of both electron-donating groups (EDG) and electron-withdrawing groups (EWG).
• X-ray analysis and NOE determination confirmed a common (E)-iminium vinylogous substructure in the cation.

Conclusions:

• Nonsymmetric diarylcarbenium tetrafluoroborates can be readily synthesized and are remarkably stable.
• The identified iminium vinylogous substructure is key to their stability.
• These stable carbenium ions offer potential for various applications in organic synthesis and materials science.