Synthesis of novel chiral oxazoline-Schiff base ligands for the catalytic asymmetric chlorination of β-keto esters
作者:Ming-Hui Qi、Fei-Jun Wang、Min Shi
DOI:10.1016/j.tetasy.2010.02.003
日期:2010.2
A series of novel monooxazoline-Schiff baseligands 1 has been successfully synthesized. The Cu(I)–1a complex showed excellent catalytic activities with up to 83% ee for the asymmetric α-chlorination of β-ketoesters.
Chiral Amino Diol Derivatives as New Modular Organocatalysts for the Enantioselective α-Chlorination of Cyclic β-Keto Esters
作者:Pablo Etayo、Ramón Badorrey、María D. Díaz-de-Villegas、José A. Gálvez
DOI:10.1002/adsc.201000594
日期:2010.12.17
Highly modularchiralaminodiolderivatives have been used as organocatalysts in the enantioselectiveα-chlorination of cyclicβ-ketoesters. Optimization of the catalyst structure and the reaction conditions has allowed the synthesis of optically active α-chlorinated products with high enantioselectivities (up to 96% ee) using inexpensive commercially available N-chlorosuccinimide (NCS) as the chlorine
Access to Both Enantiomers of α-Chloro-β-keto Esters with a Single Chiral Ligand: Highly Efficient Enantioselective Chlorination of Cyclic β-Keto Esters Catalyzed by Chiral Copper(II) and Zinc(II) Complexes of a Spiro-2,2′-bischroman-Based Bisoxazoline Li
bisoxazoline ligands (SPANbox) were found to be highly efficient in copper(II)‐ and zinc(II)‐catalyzed asymmetric chlorinations of cyclic β‐ketoesters with N‐chlorosuccinimide (NCS) as the chlorination reagent, to give the corresponding α‐chloro‐β‐ketoesters in excellent yields in 5–30 min with ee values up to 97%. The copper(II) triflate and zinc(II) triflate complexes of a single SPANbox ligand demonstrated