Aryl Shift Rearrangement in Scholl-Type Reaction Toward Nanographene

Area of Science:

• Organic Chemistry
• Materials Science
• Computational Chemistry

Background:

• The Scholl reaction is a key method for synthesizing polycyclic aromatic hydrocarbons (PAHs).
• Unexpected rearrangements during the Scholl reaction can yield complex, difficult-to-synthesize structures.
• Controlling these rearrangements is crucial for targeted PAH synthesis.

Purpose of the Study:

• To discover and characterize a novel Scholl-type reaction involving aryl shift rearrangements.
• To elucidate the mechanistic principles governing these rearrangements using computational methods.
• To develop new synthetic strategies for designing complex PAHs.

Main Methods:

• Density Functional Theory (DFT) calculations were employed for thermodynamic and kinetic studies.
• Investigation of both arenium cation and radical cation mechanisms.
• Analysis of the influence of aryl group size and position on reaction pathways.

Main Results:

• A novel Scholl-type reaction was identified, featuring 1,4-aryl and 1,2-aryl shift rearrangements.
• Armchair nanographene was successfully synthesized via this new pathway.
• DFT studies confirmed the involvement of both arenium cation and radical cation mechanisms.
• The choice between arenium cation (large aryl groups) and radical cation (small aryl groups) mechanisms was elucidated.

Conclusions:

• The study provides fundamental insights into controllable rearrangements in the Scholl reaction.
• New synthetic methodologies for accessing challenging polycyclic aromatic hydrocarbons were established.
• This work opens avenues for the rational design and synthesis of novel nanographene structures.