Beckmann rearrangements synthetic tools

The Beckmann rearrangement is one of the typical reactions of oxime derivatives and the N-substituted nitrilium ion intermediates have been widely exploited as synthetic intermediates for the preparation of nitrogen-containing heterocycles, " while few examples have been reported for the nucleophilic substitution on the sp nitrogen atom of oximes. Even though, in some of them, carbon-nitrogen bond formation is realized, these reactions have not been well generalized as synthetic tools. ... 

Other applications of NHC-based rhodium catalysts include the cyclization of acetylene carboxylic acids, cyclopropanation of olefins with diazo compounds, or aryl-aryl cross-coupling combined with dynamic kinetic resolution with the help of a lipase or Beckmann rearrangement. Thus, the chemistry of NHC-Rh catalysts is rich and varied, and we expect new catalysts and patterns of reactivity in the years to come. These will provide new tools for synthetic organic chemistry. 

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