A Novel Example of Chiral Counteranion Induced Enantioselective Metal Catalysis:  The Importance of Ion-Pairing in Copper-Catalyzed Olefin Aziridination and Cyclopropanation

Abstract

A new ion-pairing route to achieve asymmetric catalysis has been observed in the copper-catalyzed aziridination of styrene with a chiral counteranion. Structural studies suggest that enantioinduction occurs via ion-pairing of the cationic copper catalyst in the chiral pocket created by the anion. The degree of asymmetric induction can be tuned with features that affect ion-pairing, such as achiral and chiral ligands, temperature, and solvent polarity.

Copper(I) complexes supported by a heavily fluorinated bis(pyrazolyl)borate: syntheses and characterization of [H2B(3,5-(CF3)2Pz)2]CuL (where L = PPh3, N CCH3, HC CPh, H2C CHPh) and {[H2B(3,5-(CF3)2Pz)2]Cu}2(1,5-COD)

“…Copper(I) olefin complexes are also of interest for a variety of reasons [23,[72][73][74][75][76][77][78]. For example, they serve as models for copper(I) based ethylene receptor sites in plants [79,80] and resting state of the catalyst in copper catalyzed cyclopropanation reactions of olefins [72].…”

Olefin-Copper(I) Complexes and their Properties

“…When the olefin is a racemic allylic alcohol, the olefins are coordinated with high enantioface selection. Cleavage with aqueous HCl or NaCN allows a two-step resolution affording excellent enantiomeric excess (equation (19)). Compared to olefin platinum complexes, olefin-copper(I) complexes are cheaper and more labile, which are important factors in the separation of racemic olefins.…”

Multi-Walled Carbon Nanotube-Assisted Electrodeposition of Silver Dendrite Coating as a Catalytic Film

“…Many applications have been developed based on their superior properties, in areas such as biosensing, catalysis, thermal transportation, surface-enhanced Raman spectroscopy (SERS), and pollutant adsorption [4][5][6][7][8][9][10][11][12]. Among different nanostructures, the dendritic nanostructure has attracted considerable interest due to its unique morphology and properties [13][14][15][16].…”