Journal ArticleDOI
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
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TLDR
The catalytic enantioselective Henry reaction of α-keto esters with nitromethane has been developed in this article, where 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 enanti-lective reaction giving optically active β-nitro-α-hydroxy esters in high yields and with excellent enantiomeric excessAbstract:
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 i...read more
Citations
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C2-Symmetric Chiral Bis(Oxazoline) Ligands in Asymmetric Catalysis
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Recent advances in the stereoselective synthesis of β-amino acids
Mei Liu,Mukund P. Sibi +1 more
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Highly Efficient Copper-Catalyzed Nitro-Mannich Type Reaction: Cross-Dehydrogenative-Coupling between sp3 C−H Bond and sp3 C−H Bond
Zhiping Li,Chao-Jun Li +1 more
TL;DR: A novel C-C bond formation method was developed via the cross-dehydrogenative-coupling reaction catalyzed by using copper bromide in the presence of an oxidation reagent, tert-BuOOH.
Journal ArticleDOI
Asymmetric Synthesis of Tertiary Alcohols and α-Tertiary Amines via Cu-Catalyzed C−C Bond Formation to Ketones and Ketimines
Masakatsu Shibasaki,Motomu Kanai +1 more
TL;DR: Asymmetric catalysts that promote C-C bond-formation to ketones and ketimines should have high catalyst activity and enantioselectivity for synthetically more efficient addition to tetrasubstituted carbon synthesis.
Journal ArticleDOI
Recent Advances in the Catalytic Asymmetric Nitroaldol (Henry) Reaction
TL;DR: In this paper, an ambifunctional system based on La, Zn, Cu, Co and Mg metal species is described, together with some organocatalysts.
References
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The catalytic enantioselective construction of molecules with quaternary carbon stereocenters
E. J. Corey,Angel Guzman-Perez +1 more
TL;DR: A long-standing challenge to synthesis can now be met through the use of new and powerful catalytic asymmetric reactions for the assembly of complex chiral molecules with quaternary stereocenters from achiral building blocks.
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Basic character of rare earth metal alkoxides. Utilization in catalytic C-C bond-forming reactions and catalytic asymmetric nitroaldol reactions
TL;DR: In this article, the authors reported several carbon-carbon bond-forming reactions catalyzed by rare earth metal alkoxides and their application to a catalytic asymmetric nitroaldol reaction.
Journal ArticleDOI
C2-Symmetric Copper(II) Complexes as Chiral Lewis Acids. Scope and Mechanism of Catalytic Enantioselective Aldol Additions of Enolsilanes to (Benzyloxy)acetaldehyde
David A. Evans,Marisa C. Kozlowski,Jerry A. Murry,Christopher S. Burgey,Kevin R. Campos,and Brian T. Connell,Richard J. Staples +6 more
TL;DR: In this paper, the authors investigated the reaction mechanism utilizing doubly labeled silylketene acetals and showed a significant positive nonlinear effect, proposed to arise from the selective formation of the [Cu((S,S)-Ph-pybox)((R,R)-Ph -pybox)](SbF6)2 2:1 ligand:metal complex, in which chelation of (benzyloxy)acetaldehyde to the metal center to form a square pyramidal copper intermediate accounts for the obser...
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A dinuclear Zn catalyst for the asymmetric nitroaldol (Henry) reaction.
Barry M. Trost,Yeh Vince S +1 more
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Efficient Diastereoselective and Enantioselective Nitroaldol Reactions from Prochiral Starting Materials: Utilization of La-Li-6,6'-Disubstituted BINOL Complexes as Asymmetric Catalysts
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