Intramolecular Claisen condensation of keto esters catalysed by potassium triphenylmethoxide

1977 ◽  
Vol 42 (3) ◽  
pp. 998-1001 ◽  
Author(s):  
J. Šraga ◽  
P. Hrnčiar
Keyword(s):  
Claisen Condensation ◽  
Keto Esters

Non-Metal Lewis Acid-Catalyzed Cross-Claisen Condensation for β-Keto Esters

2021 ◽  
Author(s):  
Tianyu Zhang ◽  
Zhenkun Yang ◽  
Dapeng Zhou ◽  
Fuliang Meng ◽  
Zhengyu Han ◽  
...  
Keyword(s):  
Lewis Acid ◽  
Claisen Condensation ◽  
Keto Esters ◽  
Acid Catalyzed

In this work, we disclose a new catalytic and high chemoselective cross-Claisen condensation of esters. In the presence of TBSNTf2 as non-metal Lewis acid, various esters can undergo cross-Claisen condensation...

Claisen condensation of the dianion of β-keto esters

1972 ◽  
Vol 13 (23) ◽  
pp. 2405-2408 ◽  
Author(s):  
Stuart N. Huckin ◽  
Larry Weiler
Keyword(s):  
Claisen Condensation ◽  
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.

Syntheses of .alpha.-, .beta.-, and .gamma.-substituted carnitines via .beta.-keto esters

1985 ◽  
Vol 50 (19) ◽  
pp. 3627-3631 ◽  
Author(s):  
Carla A. Hosmer ◽  
Robert N. Comber ◽  
Wayne J. Brouillette
Keyword(s):  
Keto Esters ◽  
Alpha Beta

Fast, solvent-free and highly enantioselective fluorination of β-keto esters catalyzed by chiral copper complexes in a ball mill

2017 ◽  
Vol 19 (7) ◽  
pp. 1674-1677 ◽  
Author(s):  
Yifeng Wang ◽  
Haojiang Wang ◽  
Yidong Jiang ◽  
Cheng Zhang ◽  
Juanjuan Shao ◽  
...  
Keyword(s):  
Ball Mill ◽  
Copper Complexes ◽  
Solvent Free ◽  
Planetary Ball Mill ◽  
Keto Esters ◽  
Solvent Free Conditions

A fast and highly enantioselective fluorination of β-keto esters catalyzed by diphenylamine linked bis(oxazoline)-Cu(OTf)2 complexes under solvent-free conditions has been developed using a planetary ball mill.

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