Anthracene Bisurea as a Supramolecular Chloride Receptor for Additive-Free, Broad-Scope Gold(I) Catalysis

Area of Science:

• Organometallic Chemistry
• Supramolecular Chemistry
• Catalysis

Background:

• Gold catalysis is vital for synthesizing complex carbon structures.
• Traditional silver salt activators for gold(I) chloride precatalysts present issues like light sensitivity and redox interference.
• Hydrogen-bond donors offer an alternative but exhibit lower activity and limited scope due to rate-limiting Au-Cl bond cleavage.

Purpose of the Study:

• To design a self-activating gold(I) chloride complex that bypasses the limitations of silver salts and current hydrogen-bond donors.
• To enhance catalytic activity and broaden the applicability of gold-catalyzed reactions.
• To investigate the role of supramolecular anion recognition in catalyst activation and performance.

Main Methods:

• Rational design of a phosphine gold(I) chloride complex featuring an anthracene bisurea quintuple hydrogen-bond donor as a supramolecular chloride receptor.
• Evaluation of the complex's catalytic performance in various intra- and intermolecular reactions without additives.
• Mechanistic studies, including a model reaction, to elucidate the activation pathway and the role of chloride binding.

Main Results:

• The designed complex functions as a self-activating precatalyst, exhibiting catalytic activity comparable to traditional inorganic chloride scavengers.
• The supramolecular chloride receptor effectively cleaves the Au-Cl bond, leading to a zwitterionic catalyst resting state.
• This activation mechanism significantly lowers catalytic barriers, enabling high performance without external activators.

Conclusions:

• Supramolecular anion recognition moieties can be integrated into catalyst design to modulate catalyst speciation and boost performance.
• The developed self-activating gold complex demonstrates that hydrogen-bond donors can now rival inorganic chloride scavengers in catalytic activity and generality.
• This work provides a new strategy for designing highly active and versatile gold catalysts.