N,N‐Dialkylhydrazones as Versatile Umpolung Reagents in Enantioselective Anion‐Binding Catalysis

An enantioselective anion‐binding organocatalytic approach with versatile N,N‐dialkylhydrazones (DAHs) as polarity‐reversed (umpolung) nucleophiles is presented. For the application of this concept, a highly ordered hydrogen‐bond (HB) network between a carefully selected CF(3)‐substituted triazole‐based multidentate HB‐donor catalyst, the ionic substrate and the hydrazone in a supramolecular chiral ion‐pair complex was envisioned. The formation of such a network was further supported by both experimental and computational studies, which showed the crucial role of the anion as a template unit. The asymmetric Reissert‐type reaction of quinolines as a model test reaction chemoselectively delivered highly enantiomerically enriched hydrazones (up 95:5 e.r.) that could be further derivatized to value‐added compounds with up to three stereocenters.