The Copper-Catalyzed Azide-Alkyne Cycloaddition Reaction: Why Two Is Faster than One.

Area of Science:

• Synthetic Chemistry
• Catalysis
• Computational Chemistry

Background:

• The copper-catalyzed azide-alkyne cycloaddition (CuAAC) is a highly efficient and selective reaction.
• Understanding the mechanistic basis for dinuclear copper catalysis in CuAAC is crucial for further optimization.

Purpose of the Study:

• To elucidate the mechanistic preference for the dinuclear CuAAC mechanism over the mononuclear analog.
• To identify the key factors contributing to the enhanced reactivity in dinuclear CuAAC.

Main Methods:

• Application of state-of-the-art quantum chemical methods.
• Utilizing Activation Strain Model (ASM) analysis.
• Employing Kohn-Sham molecular orbital (KS-MO) theory.

Main Results:

• The dinuclear CuAAC mechanism exhibits enhanced reactivity compared to the mononuclear pathway.
• Reduced steric Pauli repulsion between the copper acetylide and azide is identified as the primary driver.
• Alleviation of strain in the copper acetylide is not the main reason for enhanced reactivity.

Conclusions:

• The study provides novel mechanistic insight into dinuclear catalysis in CuAAC reactions.
• The findings clarify the origin of enhanced reactivity in the dinuclear pathway.
• This work contributes to a deeper understanding of copper-catalyzed cycloadditions.