Kinetic resolution of α-bromophenylacetamides using quinine or Cinchona alkaloid salts
摘要:
The kinetic resolution of racemic alpha-bromophenylacetamides 1 was achieved in the presence of benzenethiolate and Cinchona alkaloid salts as phase-transfer catalysts or benzenethiol and quinine, yielding (S)-enantioenriched alpha-sulfanylated products. The observed stereoselection was rationalized on the basis of the best fitting of 1 and the resolving agent in the ternary complexes. (C) 2012 Elsevier Ltd. All rights reserved.
Catalytic asymmetric conjugate addition of isocyanoacetate to (Z)-3-substituted-2-(4-pyridyl)-acrylonitrile, a reactive class of Michael acceptor
作者:Claudia Del Fiandra、Maria Moccia、Valentina Cerulli、Mauro F. A. Adamo
DOI:10.1039/c5cc08105j
日期:——
Un-substituted isocyanoacetate ethyl ester reacted with Michael acceptors 1a–m under the catalysis of Cinchona based quaternary ammonium salts providing imines 4a–m as a single diastereoisomer and in up to 94% ees.
Asymmetric synthesis of β-amino ketones by using cinchona alkaloid-based chiral phase transfer catalysts
作者:Weihua Li、Yifeng Wang、Danqian Xu
DOI:10.1039/c8ob02484g
日期:——
A highly enantioselective nucleophilic addition of ketones to imines catalyzed by chiral phase-transfer catalysts (N-quaternised cinchona alkaloid ammonium salts) has been developed, and the process affords the Mannich reaction products with tertiary stereocenters in good to high yields (up to 95%) with excellent enantioselectivities (up to 97% ee).
Asymmetric synthesis of α,β-epoxysulfones under phase-transfer catalyzed Darzens reaction
作者:Shigeru Arai、Toshimasa Ishida、Takayuki Shioiri
DOI:10.1016/s0040-4039(98)01811-5
日期:1998.11
Enantioselective synthesis of α,β-epoxysulfones by the Darzensreaction was achieved under phase-transfer catalyzed conditions. The reaction of chloromethyl phenylsulfone with various aromatic aldehydes smoothly proceeded in the presence of a catalytic amount (10 mol %) of chiral quaternary ammonium salt derived from quinine with KOH at room temperature to afford the desired coupling products in good
Asymmetric Synthesis of α-Amino Phosphonates by Using Cinchona Alkaloid-Based Chiral Phase Transfer Catalyst
作者:Weihua Li、Yifeng Wang、Danqian Xu
DOI:10.1002/ejoc.201801013
日期:2018.10.24
imines catalyzed by a cinchona alkaloid‐based chiralphase‐transfercatalyst has been developed. The process affords the desired hydrophosphonylation of imine products with quaternary stereocenters in good to high yields (up to 95 % yield) and excellent enantioselectivities (up to 99 % ee). And this straightforward protocol can be applied to gram scale reaction effectively.
isatins obviously is an efficient and economic method for the synthesis of 3-alkynyl-3-hydroxy-2-oxindoles. The new dimeric chiral quaternary ammoniums derived from a natural chiral alkaloid, quinine, can be used as cationic inducers of the enantioselectivity for the Ag(I)-catalyzed alkynylation of isatin derivatives undermildconditions. The desired chiral 3-alkynyl-3-hydroxy-2-oxindoles can be obtained