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Geminal-atom catalysis for cross-coupling
Xiao Hai1, Yang Zheng1, Qi Yu2,3
1Department of Chemistry, National University of Singapore, Singapore, Singapore.
Nature
|September 21, 2023
Summary
Geminal-atom catalysts (GACs) pair single atoms for enhanced organic synthesis. These novel catalysts enable efficient C-X cross-couplings and complex molecule assembly, overcoming limitations of single-atom catalysts.
Area of Science:
- Heterogeneous catalysis
- Materials science
- Organic synthesis
Background:
- Single-atom catalysts (SACs) offer well-defined active sites but have limitations in complex transformations due to restricted environments.
- The spatial arrangement and electronic states of mononuclear metal species in SACs may hinder optimal catalytic activity.
Purpose of the Study:
- To introduce a novel class of heterogeneous geminal-atom catalysts (GACs) that pair single-atom sites in close proximity.
- To demonstrate the enhanced catalytic performance of GACs for diverse C-X cross-coupling reactions.
Main Methods:
- Synthesis of GACs using a polymeric carbon nitride (PCN) host with nitrogen anchoring groups for Cu coordination.
- In situ characterization and quantum-theoretical studies to elucidate reaction mechanisms.
- Testing GACs in various C-X (X = C, N, O, S) cross-coupling reactions.
Main Results:
- GACs exhibit a specific coordination and spatial proximity of Cu atoms (~4 Å separation) at high metal density.
- A cooperative bridge-coupling pathway facilitated by dynamic Cu-Cu bonding enables efficient cross-couplings with low activation barriers.
- GACs demonstrate high activity and selectivity in synthesizing complex heterocycles, sterically hindered molecules, and pharmaceuticals.
Conclusions:
- Geminal-atom catalysts represent a significant advancement over SACs for complex organic synthesis.
- The unique cooperative mechanism in GACs prevents homo-coupling and promotes diverse cross-coupling reactions.
- GACs show broad applicability for fine chemical manufacturing, including scale-up and continuous flow processes.
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