Hydrogen-Bond-Donor-Directed Switching of Enantioselectivity in the Vinylogous Aldol-Cyclization Cascade Reaction of Prostereogenic 3-Alkylidene Oxindoles with Isatins and o-Quinones

J Org Chem. 2022 Mar 4;87(5):2520-2531. doi: 10.1021/acs.joc.1c02421. Epub 2022 Jan 27.

Abstract

In this study, we reported a hydrogen-bond-donor-directed enantiodivergent vinylogous aldol-cyclization cascade reaction of 3-alkylidene oxindoles with isatins and o-quinones. Both enantiomers can be prepared by thiourea or squaramide cinchona alkaloid bifunctional organocatalysts with the same quinine scaffold. Kinetic study data provided the possible reaction mechanism for the vinylogous aldol-cyclization cascade reaction. The DFT calculation data showed the geometry of the generated dienolates from pronucleophiles dominated the observed switch of enantioselectivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aldehydes
  • Catalysis
  • Cyclization
  • Hydrogen*
  • Oxindoles
  • Quinones*

Substances

  • Aldehydes
  • Oxindoles
  • Quinones
  • Hydrogen
  • 3-hydroxybutanal