Structures and Ambident Reactivities of Azolium Enolates

Angew. Chem. Int. Ed., 2013, 52, 11163-11167 published on 29.07.2013
Angew. Chem. Int. Ed.
Oxygen versus carbon: Azolium enolates were generated by the reactions of N-heterocyclic carbenes (NHCs) with methyl phenyl ketene and characterized by X-ray crystallography. Kinetic studies show that the enolate oxygen is 20 times more nucleophilic than the carbon atom, but under thermodynamic control exclusive C-addition products were formed.
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