Navigating Scholl-Type Oxidative Coupling: An Electronic Programming Toward Path Revelation, Selectivity, and Control

Area of Science:

• Organic Chemistry
• Materials Science
• Supramolecular Chemistry

Background:

• Scholl-type oxidative aryl-aryl coupling is vital for synthesizing extended π-systems.
• Achieving regioselectivity and stepwise control in these reactions is challenging.

Purpose of the Study:

• To systematically investigate how aryl substituent electronic effects influence tetraarylthiophene (TAT) framework construction.
• To establish a predictive model for controlling C-C bond formation efficiency, selectivity, and reaction pathways.

Main Methods:

• Utilized electrochemical potentials and Hammett σp constants to correlate electronic effects with reactivity.
• Employed electronic step discrimination by pairing electronically distinct aryls to control coupling outcomes.
• Investigated sequential coupling strategies for precise π-framework synthesis.

Main Results:

• Established a clear reactivity trend based on aryl substituent electronics: OMe > Me > tBu > H > Ph > F > Cl > CHO > CF3.
• Demonstrated that electron-rich aryls promote efficient coupling, while electron-deficient groups hinder it.
• Achieved face-selective mono-cyclization products (PTs) through electronic step discrimination, enabling control over homo- and cross-coupling.

Conclusions:

• Developed a simple electronic map to predict oxidative cyclization outcomes in polyaryl architectures.
• Provided a rational approach for designing regioselective oxidative cyclizations for precise π-framework synthesis.
• Enabled precise control over sequential couplings by strategically pairing electronically distinct aryl groups.