Base-Catalyzed Cascade Cyclization of 2-Nitrochalcones and Isocyanides to Access Pyrano[3,4-<i>b</i>]indol-1(9<i>H</i>)-one Frameworks
Juan Wan, Guiyun Zeng, Shuntao Huang, Yilong Yuan, Zhuoting Xu, Yuanmin Wen, Chao Huang
Abstract
An unexpected cascade reaction of 2-nitrochalcones with isocyanoacetates has been reported for the efficient synthesis of indole carboxylic esters and pyranoindoles. The conversion was achieved by KOH-catalyzed cyclization and elimination of the nitro group with final decarbonylation-aromatization. The method was used to synthesize a series of potentially biologically active indole derivatives (49 examples) in 67-85% yields under transition-metal-free catalytic conditions.
Topics & Concepts
ChemistryDecarbonylationAromatizationIndole testCatalysisCombinatorial chemistryCascadeNitroBase (topology)Cascade reactionMedicinal chemistryStereochemistryOrganic chemistryAlkylMathematical analysisChromatographyMathematicsMulticomponent Synthesis of HeterocyclesSynthesis of Indole DerivativesCatalytic C–H Functionalization Methods