An N-heterocyclic carbene (NHC)-catalyzed chemoselective intermolecular cross-benzoin
reaction of aliphatic aldehydes with isatins is developed, affording biologically
important 3-substituted 3-hydroxyoxindoles (on gram scale) in moderate to good yields
(46–90%). The employment of a morpholinone-derived pentafluorophenyl-substituted triazolium
salt as the electron-deficient NHC pre-catalyst is essential to make the reaction
go through the cross-benzoin reaction pathway rather than the hydroacylation reaction
pathway.
Key words
N-heterocyclic carbene - chemoselective - cross-benzoin reaction - 3-hydroxyoxindole
- isatin
