kinetic resolution of 2-substituted indoline derivatives was achieved by hydrogentransfer to imines by means of a chiral phosphoric acid catalyst. The oxidative kinetic resolution was applicable to racemic alkyl- or aryl-substituted indolines, and the remaining indolines were obtained in good yields with excellent enantioselectivities.
Chiral Phosphoric Acid Catalyzed Kinetic Resolution of Indolines Based on a Self-Redox Reaction
作者:Kodai Saito、Takahiko Akiyama
DOI:10.1002/anie.201510692
日期:2016.2.24
A strategy for oxidative kineticresolution 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
We have developed a highly efficient and practical strategy for the kinetic resolution of indoline derivatives, involving a chiral Brønstedacid-catalyzed iminium ion formation and asymmetric transfer hydrogenation cascade process. The kinetic resolution allows the synthesis of 2-substituted N-benzylindolines in good yields with moderate to excellent enantioselectivities.