| Author(s) |
Glover, Stephen A
Rosser, Adam A
|
| Publication Date |
2023
|
| Abstract |
Anomeric amides have two electronegative atoms, X and Y, on nitrogen. Their combined electron demand reduces amide resonance through introduction of 2s character into the nitrogen lone pair, resulting in a pyramidal conformation and longer N-C(O) bonds, for which there is structural, spectroscopic, and theoretical evidence. Resonance can be reduced to 50% that of typical values with strongly electronegative atoms. The compromised resonance renders such amides reactive at nitrogen at which both S <sub>N</sub> 1 and S <sub>N</sub> 2 processes occur. Both are driven by n <sub>Y</sub> -σ* NX anomeric destabilization of N-X bonds. Despite weakened resonance, nucleophilic addition to the carbonyls is not observed. However, where X is a poor leaving group, anomeric destabilization leads to intramolecular rearrangements (HERON reactions) in which X migrates from nitrogen to the carbonyl, resulting in acyl substitution through cleavage of the amide bond and production of Y-stabilized nitrenes. Numerous examples of substitution reactions at nitrogen and HERON reactions are described.
|
| Citation |
Amide Bond Activation: Concepts and Reactions, p. 29-77
|
| ISBN |
9783527830244
9783527830268
9783527830251
9783527348312
|
| Link | |
| Publisher |
Wiley-VCH GmbH
|
| Edition |
1
|
| Title |
Modification of Amidic Resonance Through Heteroatom Substitution at Nitrogen: Anomeric Amides
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| Type of document |
Book Chapter
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| Entity Type |
Publication
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