Hydrogen-Bonding Asymmetric Metal Catalysis with α-Amino Acids: A Simple and Tunable Approach to High Enantioinduction
作者:Yingdong Lu、Tim C. Johnstone、Bruce A. Arndtsen
DOI:10.1021/ja904185b
日期:2009.8.19
While asymmetric transition-metal catalysis has become a powerful method for constructing chiral products, a challenge in this field is the identification of the correct ligand for high selectivity. We report here a simple approach to chiral catalyst formation: coupling of an available pool of Brønsted acids, namely, amino acid derivatives, with tunable ligands on copper catalysts. This system can
Silver-Catalyzed Alkyne Activation: The Surprising Ligand Effect
作者:Yijin Su、Mei Lu、Boliang Dong、Hao Chen、Xiaodong Shi
DOI:10.1002/adsc.201300785
日期:2014.3.10
An unexpected ligand effect was discovered in the silver(I)‐catalyzed alkyneactivation. For both aldehyde‐alkyne‐amine (A3) condensation and intermolecular alkynehydroamination, the type B complex (P:Ag=1:1) effectively promoted the reaction, while no reaction occurred with either no ligand or excess ligands under the identical conditions.
was studied. The reaction is catalyzed by coppercomplexes of enantiomerically pure bisimines, readily prepared in very high yields from the commercially available binaphthyl diamine. A very simple experimental procedure allowed to obtain at room temperature optically active propargylamines in high yields and enantioselectivity. Interestingly, bisimine/copper(I) complexes were able to promote the direct
A New Pyridyl Bis(oxazoline) Ligand Prepared fromD-Glucosamine for Asymmetric Alkynylation of Imines
作者:Mustafa Irmak、Mike M. K. Boysen
DOI:10.1002/adsc.200700592
日期:2008.2.22
A new carbohydrate-based pyridyl bis(oxazoline) has been prepared from D-glucosamine via simple steps. With this ligand enantioselectivities up to 99% were achieved in copper(I)-catalysed alkynylations of imines.
A series of highly efficient and inexpensive bioxazoline ligands were easily synthesized from tartaric acid and further explored for enantioselective addition of terminal alkynes to imines in combination with copper(II) salts. This is the first ever report showing application of bidentate bioxazoline ligands in the synthesis of propargylamines with good enantioselectivity.