Asymmetric Henry Reaction Catalyzed by <i>C</i><sub>2</sub>-Symmetric Tridentate Bis(oxazoline) and Bis(thiazoline) Complexes: Metal-Controlled Reversal of Enantioselectivity
作者:Da-Ming Du、Shao-Feng Lu、Tao Fang、Jiaxi Xu
DOI:10.1021/jo050097d
日期:2005.4.1
C2-symmetric tridentate bis(oxazoline) and bis(thiazoline) ligands with a diphenylamine backbone have been investigated in the catalytic asymmetric Henry reaction of α-keto esters with different Lewisacids. Their Cu(OTf)2 complexes furnished S enantiomers, while Et2Zn complexes afforded R enantiomers, both of them with higher enantioselectivities (up to 85% ee). Reversal of enantioselectivity in asymmetric
Enantioselective Nitroaldol Reaction of α-Keto Esters Catalyzed by a Copper(II)-Bisoxazolidine Complex
作者:Christian Wolf、Hanhui Xu
DOI:10.1055/s-0030-1259000
日期:2010.11
A wide range of aliphatic and aromatic α-keto esters has been transformed to α-hydroxy-β-nitro esters via the Cu(II)-bisoxazolidine-catalyzed Henry reaction. In the presence of 10 mol% of the chiral catalyst, nitroaldol products were obtained in up to 95% yield and 76% ee.
catalytic asymmetric Henry reaction of α-keto esters, 2-acylpyridines and 2-acylpyridine N-oxides. The corresponding β-nitro-α-hydroxy esters were obtained in good to excellent yields (up to 99%) with a high enantiomeric excess (ee) (up to 94%) with a catalyst loading of 1–2 mol%. The desired products of 2-acylpyridines and 2-acylpyridine N-oxides, which were simple methyl ketones, were obtained in medium
Enantioselective addition of nitromethane to α-keto esters catalyzed by copper(<scp>ii</scp>)–iminopyridine complexes
作者:Gonzalo Blay、Victor Hernández-Olmos、José R. Pedro
DOI:10.1039/b716446g
日期:——
The coppercomplex of a chiral iminopyridine easily prepared from (R)-(-)-fenchone and picolylamine catalyzes the enantioselective Henry (nitroaldol) reaction between nitromethane and alpha-keto esters. Good yields and modest to good enantioselectivities are obtained for a wide range of alpha-keto esters, bearing aromatic, alkyl or alkenyl groups attached to the ketone carbonyl group.
Catalytic Asymmetric Nitroaldol (Henry) Reaction with a Zinc-Fam Catalyst
作者:Adnan Bulut、Ayhan Aslan、Özdemir Dogan
DOI:10.1021/jo8010073
日期:2008.9.19
Ferrocenyl-substituted aziridinylmethanol (Fam-1) was used as a catalyst with zinc for the asymmetric nitroaldol (Henry) reaction. This catalyst worked with a variety of aldehydes (aromatic, aliphatic, alpha,beta-unsaturated, and heteroaromatic) and alpha-ketoesters to give the nitroaldol product in up to 97% yield and 91% ee. The chiral ligand can be recovered and recycled without losing its activity