First use of cactus and cushcush as biocatalysts in the enantioselective reduction of β -keto esters

2017 ◽  
Vol 96 ◽  
pp. 126-131
Author(s):  
Mauricio M. Victor ◽  
José E. Uchôa ◽  
Valéria Belli Riatto
Keyword(s):  
Enantioselective Reduction ◽  
Keto Esters

Enantioselective reduction of β-keto esters

1991 ◽  
Vol 32 (34) ◽  
pp. 4227-4230 ◽  
Author(s):  
Douglass F Taber ◽  
Lee J Silverberg
Keyword(s):  
Enantioselective Reduction ◽  
Keto Esters

ChemInform Abstract: Enantioselective Reduction of β-Keto Esters.

ChemInform ◽  
2010 ◽  
Vol 23 (20) ◽  
pp. no-no
Author(s):  
D. F. TABER ◽  
L. J. SILVERBERG
Keyword(s):  
Enantioselective Reduction ◽  
Keto Esters

Towards Enantioselective Electrophilic Trifluoromethylation of β-Keto Esters

2006 ◽  
Author(s):  
Dominique Cahard ◽  
Jun-An Ma ◽  
Vitaliy Petrik
Keyword(s):  
Keto Esters

Diastereoselective Reduction of Selected α-substituted β-keto Esters and the Assignment of the Relative Configuration by 1H-NMR Spectroscopy

2020 ◽  
Vol 07 ◽  
Author(s):  
Christian Trapp ◽  
Corinna Schuster ◽  
Chris Drewniok ◽  
Dieter Greif ◽  
Martin Hofrichter
Keyword(s):  
Nmr Spectroscopy ◽  
1H Nmr ◽  
1H Nmr Spectroscopy ◽  
Selective Reduction ◽  
Reducing Agents ◽  
Relative Configuration ◽  
Curtius Rearrangement ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Diastereoselective Reduction

Background:: Chiral β-hydroxy esters and α-substituted β-hydroxy esters represent versatile building blocks for pheromones, β-lactam antibiotics and 1,2- or 1,3-aminoalcohols. Objective:: Synthesis of versatile α-substituted β-keto esters and their diastereoselective reduction to the corresponding syn- or anti-α-substituted β-hydroxy esters. Assignment of the relative configuration by NMR-spectroscopy after a CURTIUS rearrangement of α-substituted β-keto esters to 4-substituted 5-methyloxazolidin-2-ones. Method:: Diastereoselective reduction was achieved by using different LEWIS acids (zinc, titanium and cerium) in combination with complex borohydrides as reducing agents. Assignment of the relative configuration was verified by 1H-NMR spectroscopy after CURTIUS-rearrangement of α-substituted β-hydroxy esters to 4-substituted 5-methyloxazolidin-2-ones. Results:: For the syn-selective reduction, titanium tetrachloride (TiCl4) in combination with a pyridine-borane complex (py BH3) led to diastereoselectivities up to 99% dr. High anti-selective reduction was achieved by using cerium trichloride (CeCl3) and steric hindered reducing agents such as lithium triethylborohydride (LiEt3BH). After CURTIUS-rearrangement of each α-substituted β-hydroxy ester to the corresponding 4-substituted 5-methyloxazolidin-2-one, the relative configuration was confirmed by 1H NMR-spectroscopy. Conclusion:: We have expanded the procedure of LEWIS acid-mediated diastereoselective reduction to bulky α-substituents such as the isopropyl group and the electron withdrawing phenyl ring.

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