<i>N</i>,<i>N</i>‐Dialkylhydrazones as Versatile Umpolung Reagents in Enantioselective Anion‐Binding Catalysis
Melania Gómez‐Martínez, María del Carmen Pérez‐Aguilar, Dariusz G. Piekarski, Constantin G. Daniliuc, Olga Garcı́a Mancheño
Abstract
Abstract 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.