Catalytic Enantioselective Addition of Dialkylzinc to <i>N</i>-Diphenylphosphinoylimines. A Practical Synthesis of α-Chiral Amines
作者:Alessandro A. Boezio、André B. Charette
DOI:10.1021/ja027673x
日期:2003.2.19
The enantioselectiveaddition of dialkylzincreagents to N-diphenylphosphinoylimines derived from aryl-, furyl-, and cyclopropylaldehydes is efficiently catalyzed by a copper(II) triflate/(R,R)-MeDUPHOS complex. The yields are high (51-98%), and the enantiomeric excesses vary from 85 to 96%. This route provides a practical route to alpha-chiral amines.
N-Benzyl-l-prolinol: an efficient catalyst for the enantioselective addition of dialkylzinc reagents to N-(diphenylphosphinoyl)imines
作者:Raquel Almansa、David Guijarro、Miguel Yus
DOI:10.1016/j.tetasy.2007.03.026
日期:2007.4
Commercially available N-benzyl-l-prolinol has shown to be a very efficientcatalyst for the enantioselectiveaddition of dialkylzinc reagents to N-(diphenylphosphinoyl)imines. The use of 0.5 equiv of this β-aminoalcohol as a catalyst leads to the expected addition products in good yields and with ees up to 92% in a reaction time of only 4 h at room temperature. This ee is almost equal to the highest
General Method for the Expedient Synthesis of Salt-Free Diorganozinc Reagents Using Zinc Methoxide
作者:Alexandre Côté、André B. Charette
DOI:10.1021/ja710864p
日期:2008.3.1
Zn(OMe)2 with readily available Grignard reagents, it was possible to induce the complete precipitation of magnesium salts and then obtain salt-free diorganozinc reagents after centrifugation/filtration. This practical method to generate dialkylzincreagents as well as mixed diorganozinc reagents was successfully tested in various catalyticenantioselectivereactions, proving the purity of the product and
Asymmetric, Catalytic Synthesis of α-Chiral Amines Using a Novel Bis(phosphine) Monoxide Chiral Ligand
作者:Alessandro A. Boezio、Julien Pytkowicz、Alexandre Côté、André B. Charette
DOI:10.1021/ja038291+
日期:2003.11.1
We have shown that Me-DuPHOS monoxide (BozPHOS) is a very effective ligand in the copper-catalyzed addition of dialkylzinc to N-phosphinoylimines providing access to alpha-chiral amines. The new ligand is particularly effective for the addition of the lesser reactive dimethylzinc. The major advantages of this process are high yields, broad substrate scope, and high enantioselectivities with low catalyst