Chiral Phosphoric Acid Catalyzed Kinetic Resolution of Indolines Based on a Self-Redox Reaction
Kodai Saito1,2, Takahiko Akiyama3
1Department of Chemistry, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588, Japan.
Abstract:
A strategy for oxidative kinetic resolution of racemic indolines was developed, employing salicylaldehyde derivative as the pre-resolving reagent and chiral phosphoric acid as the catalyst. The iminium intermediate, formed by the condensation reaction of an enantiomer of indoline with salicylaldehyde derivative, was hydrogenated by the same enantiomer of indoline to afford another enantiomer of indoline by a self-redox mechanism. The oxidative kinetic resolution of 2-aryl-substituted indolines proceeded to give enantiomers in good yields with excellent enantioselectivities.
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