Novel approach for formation of carbon nitrogen bonds
Researchers at Rice University, Houston, have devised a non catalytic approach to the formation of carbon-nitrogen bonds. Their method, which relies on an umpolung (polarity-reversal) reagent, promises an operationally simple, scalable and environmental friendly alternative to current transitionmetal-catalyzed cross-coupling routes for producing amines, they believe.
The method can directly produce symmetrical and unsymmetrical diaryl-, arylalkyl- and dialkylamines. The development of a practical single and double umpolung of nitrogen provides unprecedented flexibility for coming up with efficient synthesis routes, the re- searchers believe.
“Overall, this new N-umpolung approach opens up chemical routes that were previously only available by the use of expensive transition metals and ligands. One huge advantage here is that no lengthy optimization is required when a particular C–N bond is to be made. Even aryl-nitrogen bonds can be prepared at or below ambient temperatures. The N-umpolung reagent is inexpensive, the aryl- as well as alkyl Grignards are commercially available or can be readily prepared,” noted László Kürti, an associate professor of chemistry at Rice. The findings are published in the Journal of the American Chemical Society (JACS).
“We believe that the degree of N-electrophilicity can be further modulated by changing the structure of the N-umpolung reagent. Therefore, we are actively making new and more powerful N-umpolung reagents and evaluating these in a variety of carbon-nitrogen bond-forming transformations. In summary, our N-electrophilic imines indeed will likely be very useful substrates and valuable N-sources in many mechanistically different transformations,” says Kurti.