N‐Heterocyclic Carbene (NHC)‐Catalyzed Transformations Involving Azolium Enolates

Abstract The recent advances in the N‐heterocyclic carbene (NHC)‐organocatalyzed generation of azolium enolate intermediates and their subsequent interception with electrophiles are highlighted. The NHC‐bound azolium intermediates are generated by the addition of NHCs to suitably substituted aldehydes, acid derivatives or ketenes. A broad range of coupling partners can intercept the azolium enolates to form [2+n] cycloadducts (n=2,3,4) and various α‐functionalized compounds. The enantioselective synthesis of the target compounds are achieved with the use of chiral NHCs. Herein, we summarized the development that occurred in this subclass of NHC catalysis.