Ligand-free reductive amination via Pd-coated mechanocatalysis
Maximilian Wohlgemuth1, Sarah Schmidt1, Lars Beißel1
1Inorganic Chemistry I, Ruhr University Bochum, Universitätsstraße 150, 44801, Bochum, Germany. Maximilian.wohlgemuth@rub.de.
Direct mechanocatalysis enables reductive amination through a sequential milling protocol. Hydrophobic additives enhance amine yields up to 88% by excluding water, applicable to diverse carbonyl compounds and amines.
Area of Science:
- Organic Chemistry
- Catalysis
- Green Chemistry
Background:
- Reductive amination is a crucial organic transformation for synthesizing amines.
- Traditional methods often require harsh conditions or complex setups.
- Mechanocatalysis offers a solvent-free alternative for chemical reactions.
Purpose of the Study:
- To develop a direct mechanocatalytic reductive amination protocol.
- To enhance reaction efficiency and amine yields using mechanical force.
- To explore the use of liquid additives in mechanocatalysis.
Main Methods:
- A sequential two-frequency milling protocol was employed.
- Imine formation and hydrogenation steps were separated within the milling process.
- Strongly hydrophobic liquid additives were utilized to exclude water.
Main Results:
- Amine yields of up to 88% were achieved.
- The protocol demonstrated applicability to various aldehydes, ketones, and amines.
- Hydrophobic additives significantly accelerated the reaction rate.
Conclusions:
- Direct mechanocatalysis is a viable strategy for reductive amination.
- Sequential milling and hydrophobic additives improve efficiency and yield.
- This method provides a greener and potentially more scalable route to amines.
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