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Chiral Brønsted Acid from Chiral Phosphoric Acid Boron Complex and Water: Asymmetric Reduction of Indoles.

Kai YangYixian LouChenglan WangLiang-Wen QiTongchang FangFeng ZhangHetao XuLu ZhouWangyang LiGuan ZhangPeiyuan YuQiuling Song
Published in: Angewandte Chemie (International ed. in English) (2020)
A new chiral Brønsted acid, generated in situ from a chiral phosphoric acid boron (CPAB) complex and water, was successfully applied to asymmetric indole reduction. This "designer acid catalyst", which is more acidic than TsOH as suggested by DFT calculations, allows the unprecedented direct asymmetric reduction of C2-aryl-substituted N-unprotected indoles and features good to excellent enantioselectivities with broad functional group tolerance. DFT calculations and mechanistic experiments indicates that this reaction undergoes C3-protonation and hydride-transfer processes. Besides, bulky C2-alkyl-substituted N-unprotected indoles are also suitable for this system.
Keyphrases
  • ionic liquid
  • density functional theory
  • molecular docking
  • capillary electrophoresis
  • molecular dynamics
  • molecular dynamics simulations
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  • mass spectrometry
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