Organocatalytic Asymmetric Cyclopropanation of 3-Acylcoumarins with 3-Halooxindoles: Access to Spirooxindole-cyclopropa[c]coumarin Compounds

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.

Automated summary

The study introduces a highly diastereo- and enantioselective cyclopropanation reaction of 3-acylcoumarins with 3-halooxindoles catalyzed by an organocatalyst, resulting in compounds bearing three continuous stereocenters with high to excellent selectivities. The importance of the ammonium ylide intermediate in the catalytic process was revealed through HRMS analysis.