Organocatalytic Asymmetric Cyclopropanation of 3-Acylcoumarins with 3-Halooxindoles: Access to Spirooxindole-cyclopropa[<i>c</i>]coumarin Compounds
Wei‐Cheng Yuan, Chuan-Wen Lei, Jian‐Qiang Zhao, Zhen‐Hua Wang, Yong You
Abstract
A highly diastereo- and enantioselective cyclopropanation reaction of 3-acylcoumarins with 3-halooxindoles catalyzed by an organocatalyst through a [2 + 1] Michael/intramolecular cyclization process was developed. This scenario provides a facile strategy to access spirooxindole-cyclopropa[c]coumarin compounds bearing three continuous stereocenters, including two vicinal quaternary all-carbon stereocenters with high to excellent diastereo- and enantioselectivities. The HRMS study revealed the vital importance of the ammonium ylide intermediate in the catalytic process.
Topics & Concepts
StereocenterCyclopropanationEnantioselective synthesisChemistryIntramolecular forceVicinalCatalysisMichael reactionCoumarinOrganocatalysisOrganic chemistryCombinatorial chemistryStereochemistryCyclopropane Reaction MechanismsAsymmetric Synthesis and CatalysisSynthetic Organic Chemistry Methods