443793-46-2Relevant academic research and scientific papers
Enantioselective nitroaldol reaction of α-keto esters catalyzed by a copper(II)-bisoxazolidine complex
Xu, Hanhui,Wolf, Christian
experimental part, p. 2765 - 2770 (2011/02/22)
A wide range of aliphatic and aromatic -keto esters has been transformed to α-hydroxy-β-nitro esters via the Cu(II)-bisoxa-zolidine-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.
Enantioselective addition of nitromethane to α-keto esters catalyzed by copper(II)-iminopyridine complexes
Blay, Gonzalo,Hernandez-Olmos, Victor,Pedro, Jose R.
experimental part, p. 468 - 476 (2008/10/09)
The copper complex of a chiral iminopyridine easily prepared from (R)-(-)-fenchone and picolylamine catalyzes the enantioselective Henry (nitroaldol) reaction between nitromethane and α-keto esters. Good yields and modest to good enantioselectivities are obtained for a wide range of α-keto esters, bearing aromatic, alkyl or alkenyl groups attached to the ketone carbonyl group. The Royal Society of Chemistry 2008.
Enantioselective nitroaldol reaction of α-ketoesters catalyzed by cinchona alkaloids
Li, Hongming,Wang, Baomin,Deng, Li
, p. 732 - 733 (2007/10/03)
The development of highly enantioselective and general catalytic nitroaldol (Henry) reactions with ketones is a challenging yet desirable task in organic synthesis. In this communication, we report an asymmetric nitroaldol reaction with α-ketoesters catalyzed by a new C6′-OH cinchona alkaloid catalyst. This is the first highly efficient organocatalytic asymmetric Henry reaction with ketones. This reaction is operationally simple and affords high enantioselectivity as well as good to excellent yield for a broad range of α-ketoesters. . Copyright
Copper-catalyzed enantioselective Henry reactions of α-keto esters: An easy entry to optically active β-nitro-α-hydroxy esters and β-amino-α-hydroxy esters
Christensen, Christina,Juhl, Karsten,Hazell, Rita G.,Jorgensen, Karl Anker
, p. 4875 - 4881 (2007/10/03)
The catalytic enantioselective Henry reaction of α-keto esters with nitromethane has been developed. The reaction conditions have been optimized by the screening of different chiral Lewis acids, solvents, and bases, and it was found that the copper(II)-tert-butyl bisoxazoline complex in combination with triethylamine catalyzed a highly enantioselective reaction giving optically active β-nitro-α-hydroxy esters in high yields and with excellent enantiomeric excesses. The scope of the reaction is demonstrated by the reaction of a variety of different α-keto esters. The catalytic enantioselective Henry reaction of β,γ-unsaturated-α-keto esters proceeds as a 1,2-addition reaction exclusively, in contrast to the uncatalyzed reaction where both the 1,2- and 1,4-addition products are formed. It is demonstrated that the β-nitro-α-hydroxy esters can be converted into, e.g., Boc-protected β-amino-α-hydroxy esters in high yields and without loss of optical purity. The mechanism for the reaction is discussed, and it is postulated that both the α-keto ester and nitromethane/nitronate is coordinated to the metal center during the reaction course.
