Metal-Free Catalyst for the Chemoselective Methylation of Amines Using Carbon Dioxide as a Carbon Source

N‐methylation of amines is an important step in the synthesis of many pharmaceuticals and has been widely applied in the preparation of other key intermediates and chemicals. Therefore, the development of efficient methylation methods has attracted considerable attention. In this respect, carbon dio...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2014-11, Vol.53 (47), p.12876-12879
Main Authors: Das, Shoubhik, Bobbink, Felix D., Laurenczy, Gabor, Dyson, Paul J.
Format: Article
Language:English
Subjects:
Amines
Carbenes
Carbon
Carbon dioxide
Catalysts
Esters
Ethers
Methylation
N-heterocyclic carbenes
organocatalysis
sustainable chemistry
Synthesis
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Summary:N‐methylation of amines is an important step in the synthesis of many pharmaceuticals and has been widely applied in the preparation of other key intermediates and chemicals. Therefore, the development of efficient methylation methods has attracted considerable attention. In this respect, carbon dioxide is an attractive C1 building block because it is an abundant, renewable, and nontoxic carbon source. Consequently, we developed a highly chemoselective, metal‐free catalytic system that operates under ambient conditions for the N‐methylation of amines. The methylation of amines with CO2 as C1 source and Ph2SiH2 as reducing agent was achieved with an N‐heterocyclic carbene (NHC) as the catalyst. The catalyst is tolerant toward a variety of functional groups (including esters and ethers, nitro, nitrile, and carbonyl groups, and unsaturated CC bonds); the reaction uses commercially available reagents and can be performed on a gram scale.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.201407689