Aldol Type Condensations of β-Keto Ester Dianions

1974 ◽  
Vol 52 (11) ◽  
pp. 2157-2164 ◽  
Author(s):  
Stuart Nicholas Huckin ◽  
Larry Weiler
Keyword(s):  
Conjugate Addition ◽  
Methyl Acetoacetate ◽  
Keto Ester ◽  
Unsaturated Ketones ◽  
Keto Esters ◽  
Hydroxy Esters ◽  
Carbonyl Addition

The dianion of methyl acetoacetate reacts with ketones and aldehydes to yield δ -hydroxy-β-keto esters. These hydroxy esters can be dehydrated to the corresponding γ,δ-unsaturated-β-keto esters which are useful in annelation reactions to form cyclic β-keto esters. The dianion of methyl acetoacetate does not appear to undergo conjugate addition to simple α,β-unsaturated ketones, instead only carbonyl addition occurs.

Ring formation via β-keto ester dianions

1977 ◽  
Vol 55 (6) ◽  
pp. 996-1000 ◽  
Author(s):  
Phaik-Eng Sum ◽  
Larry Weiler
Keyword(s):  
Membered Ring ◽  
Ring Formation ◽  
Methyl Acetoacetate ◽  
Keto Ester ◽  
Keto Esters

The reaction of α,ω-dihalides with the dianion of methyl acetoacetate gives a mixture of mono- and bisalkylated products. The monoalkylated products can be cyclized via the monoanion to cyclic β-keto esters with a seven- or eight-membered ring. Alternatively these monoalkylated products can be cyclized via the dianion to γ-cyclopentyl- or γ-cyclohexyl-β-keto esters.

scholarly journals The enantioselective β-keto ester reductions by Saccharomyces cerevisiae

2006 ◽  
Vol 71 (8-9) ◽  
pp. 889-894 ◽  
Author(s):  
Nosrat Mahmoodi ◽  
Hassan Tajik ◽  
Khalil Tabatabaeian ◽  
Mahmood Shahbazi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Calcium Phosphate ◽  
Potassium Dihydrogen Phosphate ◽  
Dihydrogen Phosphate ◽  
Ammonium Tartrate ◽  
Potassium Dihydrogen ◽  
Keto Ester ◽  
Keto Esters ◽  
Diammonium Salt ◽  
Hydroxy Esters

The enantioselective yeast reduction of aromatic ?-keto esters, by use of potassium dihydrogen phosphate, calcium phosphate (monobasic), magnesium sulfate and ammonium tartrate (diammonium salt) (10:1:1:50) in water at pH7 as a buffer for 72-120h with 45-90 % conversion to the corresponding aromatic ?-hydroxy esters was achieved by means of Saccharomyces cerevisiae.

Synthesis and cyclization reactions with pyrazolopyrimidinyl keto esters part I. Reactivity of pyrazolopyrimidinyl β-keto ester and pyrazolopyrimidinyl α,β-unsaturated ketones

2006 ◽  
Vol 60 (5) ◽  
Author(s):  
M. Awas
Keyword(s):  
Spectral Analysis ◽  
Biological Activity ◽  
Chemical Transformations ◽  
Cyclization Reactions ◽  
Keto Ester ◽  
Unsaturated Ketones ◽  
Keto Esters ◽  
Chemical Behaviour ◽  
Derivatives Of

Abstract5-Acetyl-4,5-dihydro-1-phenylpyrazolo[3,4-d]pyrimidin-4-one was prepared and subjected to various chemical transformations to give novel 5-heterocyclic pyrazolopyrimidinone derivatives of expected important biological activity. Then, the latter compounds were used to obtain β-keto ester and α,β-unsaturated carbonylpyrazolopyrimidinones which were used as alternate precursors to produce new pyrazolopyrimidinones substituted with five-membered heterocycles such as pyrazole and isoxazole. The structure of these compounds was identified on the basis of their chemical behaviour as well as elemental and spectral analysis.

The Acylation of β-Keto Ester Dianions

1974 ◽  
Vol 52 (8) ◽  
pp. 1343-1351 ◽  
Author(s):  
Stuart Nicholas Huckin ◽  
Larry Weiler
Keyword(s):  
Methyl Acetoacetate ◽  
Keto Ester ◽  
Keto Esters

A method for the successful acylation of the dianion of simple β-keto esters to yield β,δ-diketo esters has been developed. The dianion of methyl acetoacetate also reacts with the monoanion of methyl acetoacetate to give a triketo ester which cyclizes to methyl orsellinate. These dianions also add to nitriles to give 5-amino-3-keto-4-pentenoates which may in some cases cyclize to 4-hydroxypyridones.

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.

Potassium Phosphate or Silica Sulfurc Acid Catalyzed Conjugate Addition of Thiols to α,β-Unsaturated Ketones at Room Temperature under Solvent-Free Conditions.

ChemInform ◽  
2007 ◽  
Vol 38 (14) ◽  
Author(s):  
D. M. Pore ◽  
M. S. Soudagar ◽  
U. V. Desai ◽  
T. S. Thopate ◽  
P. P. Wadagaonkar
Keyword(s):  
Room Temperature ◽  
Potassium Phosphate ◽  
Conjugate Addition ◽  
Solvent Free ◽  
Unsaturated Ketones ◽  
Solvent Free Conditions ◽  
Acid Catalyzed

Green Protocol for Conjugate Addition of Thiols to α,β-Unsaturated Ketones Using a [Bmim]PF6/H2O System

2003 ◽  
Vol 68 (18) ◽  
pp. 7098-7100 ◽  
Author(s):  
J. S. Yadav ◽  
B. V. S. Reddy ◽  
Gakul Baishya
Keyword(s):  
Conjugate Addition ◽  
Green Protocol ◽  
Unsaturated Ketones
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