New Application of Bromotrimethylsilane: Elaboration of Aldehydes/Ketones into Homologous α,β-Unsaturated Esters via β-Hydroxy Esters.

ChemInform ◽  
2005 ◽  
Vol 36 (29) ◽  
Author(s):  
Suresh C. Suri ◽  
Jacob C. Marcischak
Keyword(s):  
Unsaturated Esters ◽  
Hydroxy Esters

Thiol esters in organic synthesis. X. A new approach to 1,5-ketols and 5-hydroxy esters using S,S'-diethyl dithiomalonate as an ethanol carbanion equivalent

1982 ◽  
Vol 60 (1) ◽  
pp. 94-96 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Isaac V. Oppong
Keyword(s):  
Organic Synthesis ◽  
Raney Nickel ◽  
Michael Addition ◽  
New Approach ◽  
Unsaturated Esters ◽  
Thiol Esters ◽  
Hydroxy Esters

Michael addition of S,S′-diethyl dithiomalonate to conjugated enones and α,β-unsaturated esters followed by reduction with Raney nickel gave rise to 1,5-ketols and 5-hydroxy esters respectively in good yields.

ChemInform Abstract: Reductive Reformatsky-Honda Reaction of α,β-Unsaturated Esters: Facile Formation of 1,3-Dicarbonyl Compounds and β-Hydroxy Esters.

ChemInform ◽  
2012 ◽  
Vol 43 (26) ◽  
pp. no-no
Author(s):  
Kazuyuki Sato ◽  
Motoyuki Isoda ◽  
Shizuka Ohata ◽  
Shuhei Morita ◽  
Atsushi Tarui ◽  
...  
Keyword(s):  
Dicarbonyl Compounds ◽  
Unsaturated Esters ◽  
Hydroxy Esters

Reductive Reformatsky-Honda Reaction of α,β-Unsaturated Esters: Facile Formation of 1,3-Dicarbonyl Compounds and β-Hydroxy Esters

2012 ◽  
Vol 354 (2-3) ◽  
pp. 510-514 ◽  
Author(s):  
Kazuyuki Sato ◽  
Motoyuki Isoda ◽  
Shizuka Ohata ◽  
Shuhei Morita ◽  
Atsushi Tarui ◽  
...  
Keyword(s):  
Dicarbonyl Compounds ◽  
Unsaturated Esters ◽  
Hydroxy 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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