Aza-Henry and aza-Knoevenagel reactions of nitriles for the synthesis of pyrido[1,2-<i>a</i>]indoles
Rajesh R. Zalte, Alexey А. Festa, Никита Е. Голанцов, S. Karthikeyan, Victor B. Rybakov, А. В. Варламов, Rafael Luque, Leonid G. Voskressensky
Abstract
N-(Propargyl)indole-2-carbonitriles undergo DBU-catalyzed addition of CH-acids to nitriles, followed by cyclization to give 9-aminopyrido[1,2-a]indoles. The reaction proceeds through the initial formation of a push-pull enamine, alkyne-allene rearrangement and intramolecular nucleophilic cyclization. Nitromethane and malonate esters can be employed as the CH-acids. The resulting compounds were found to exhibit fluorescence properties.
Topics & Concepts
ChemistryKnoevenagel condensationNitromethaneAlleneIndole testEnamineAlkyneIntramolecular forceNucleophilic additionMedicinal chemistryNucleophileMalononitrileCoumarinPropargylOrganic chemistryCatalysisCatalytic C–H Functionalization MethodsAsymmetric Synthesis and CatalysisChemical synthesis and alkaloids