Oxidation of carbohydrates with chromium trioxide in acetic acid. I. Glycosides

1970 ◽  
Vol 23 (6) ◽  
pp. 1209 ◽  
Author(s):  
SJ Angyal ◽  
K James
Keyword(s):  
Acetic Acid ◽  
Hydrogen Atom ◽  
Catalytic Hydrogenation ◽  
Chromium Trioxide ◽  
Keto Ester ◽  
Keto Esters ◽  
Branched Chain ◽  
Acetyl Migration

Fully acetylated methyl β-D-hexopyranosides are oxidized by chromium trioxide in acetic acid to acetylated methyl 5-hexulosonates. Catalytic hydrogenation of these keto esters leads into the L-series. The corresponding a-D-glycosides are not oxidized in the same way, with the exception of methyl tetra-O-acetyl-α-D-idopyranoside. Both α- and β-anomers of the acetylated fnranosides are oxidized to aoetylated methyl 4-hexulosonates. The octaacetates of α- and β-lactose are similarly oxidized, the ring of the galactose moiety being opened. The methyl pyranoside of a branched-chain sugar, with no hydrogen atom on C5, is oxidized to a 4-keto ester, acetyl migration occurring from O4 to O5.

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.

Catalytic Hydrogenation of Acetic Acid to Acetaldehyde: Synergistic Effect of Bifunctional Co/Ce‐Fe Oxide Solid Solution Catalysts

2019 ◽  
Vol 37 (7) ◽  
pp. 709-719 ◽  
Author(s):  
Naixu Li ◽  
Qi Zhang ◽  
Rehana Bibi ◽  
Quanhao Shen ◽  
Richard Ngulube ◽  
...  
Keyword(s):  
Solid Solution ◽  
Acetic Acid ◽  
Synergistic Effect ◽  
Catalytic Hydrogenation ◽  
Fe Oxide ◽  
Oxide Solid Solution

Synthetic application of cyclobutanes V. α-Carbalkoxymethylation of α, β-unsaturated ketones

1977 ◽  
Vol 55 (5) ◽  
pp. 822-830 ◽  
Author(s):  
Hsing-Jang Liu ◽  
Patrick Chi-Lin Yao
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Acetic Anhydride ◽  
Potassium Carbonate ◽  
Alkyl Iodide ◽  
Keto Ester ◽  
Unsaturated Ketones ◽  
Synthetic Application ◽  
Hydrolysis Of ◽  
Villiger Oxidation

Two general methods for α-carbalkoxymethylation of both enolizable and nonenolizable (towards the γ-position) α,β-unsaturated ketones have been developed. Method A involves three synthetic steps: photocycloaddition of the starting enone to 1,1-dimethoxyethylene, hydrolysis–oxidation of the adduct with acetic acid and 30% hydrogen peroxide, and O-alkylation of the resulting mixture of lactone and acid using anhydrous potassium carbonate and an alkyl iodide, e.g., 13 → 17 → 21 + 22 → 23. Method B differs from method A in the means of securing the required cyclobutanone intermediate. Thus, photocycloaddition of 13 to vinyl acetate followed by hydrolysis of the adduct gave two epimeric keto alcohols 39 whose oxidation with dimethyl sulfoxide and acetic anhydride afforded diketone 40. Baeyer–Villiger oxidation of 40 followed by methylation of the products 21 and 22 completed the overall α-carbomethoxymethylation process to give keto ester 23.

New Route to Branched-chain Aminodeoxy Sugars by Reaction of Ketoses with Acetonitrile. Synthesis of Methyl 3-C-2′-Aminoethyl-2-deoxy-α-D-arabino-hexopyranoside

1974 ◽  
Vol 52 (1) ◽  
pp. 51-54 ◽  
Author(s):  
Alex Rosenthal ◽  
G. Schöllnhammer
Keyword(s):  
Catalytic Hydrogenation ◽  
Liquid Ammonia ◽  
High Yield ◽  
Lithium Amide ◽  
Branched Chain

Addition of methyl 4,6-O-benzylidene-2-deoxy-α-D-erythro-hexopyranosid-3-ulose (1) to acetonitrile in liquid ammonia at −50 to −60° in the presence of lithium amide gave, in high yield, crystalline methyl 4,6-O-benzylidene-3-C-cyanomethyl-2-deoxy-α-D-arabino-hexopyranoside (2) exclusively. The proof of structure 2 is described. Debenzylidenation of 2 afforded the branched-chain cyano glycoside 3. Compound 3 was converted into its 3,4,6-tri-O-acetate (8) and 4,6-di-O-p-nitrobenzoate (9) derivatives. Catalytic hydrogenation of 3 over rhodium on alumina yielded methyl 3-C-2′-aminoethyl-2-deoxy-α-D-arabino-hexopyranoside which was characterized as its N-2,4-dinitrophenyl derivative (7).

Ruthenium catalyzed asymmetric hydrogenation of α- and β-keto esters in ionic liquids using chiral P-Phos ligand

2005 ◽  
Vol 83 (6-7) ◽  
pp. 903-908 ◽  
Author(s):  
Kim Hung Lam ◽  
Lijin Xu ◽  
Lichun Feng ◽  
Jiwu Ruan ◽  
Qinghua Fan ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Room Temperature ◽  
Asymmetric Hydrogenation ◽  
Room Temperature Ionic Liquids ◽  
Keto Ester ◽  
Keto Esters ◽  
Simple Extraction

Chiral dipyridylphosphine ligand P-Phos was used in the Ru catalyzed asymmetric hydrogenation of α- and β-keto esters in room temperature ionic liquids (RTILs) with high conversions and good to excellent enantioselectivities. The catalyst was recycled by simple extraction and reused five times without loss of activity and enantioselectivity.Key words: ruthenium, asymmetric hydrogenation, keto ester, ionic liquids, P-Phos.

Scope and limitations in the use of N-(PhF)serine-derived cyclic sulfamidates for amino acid synthesis

2001 ◽  
Vol 79 (1) ◽  
pp. 94-104 ◽  
Author(s):  
Lan Wei ◽  
William D Lubell
Keyword(s):  
Amino Acid ◽  
Sodium Azide ◽  
Ring Opening ◽  
Acid Synthesis ◽  
Potassium Thiocyanate ◽  
Dimethyl Malonate ◽  
Amino Acid Synthesis ◽  
Keto Ester ◽  
Keto Esters ◽  
Nucleophilic Displacement

Ring-opening of N-(PhF)serine-derived cyclic sulfamidate 17 was achieved with different nucleophiles (β-keto esters, β-keto ketones, dimethyl malonate, nitroethane, sodium azide, imidazole, and potassium thiocyanate) to prepare a variety of amino acid analogs. Two different pathways for ring opening of 17 were elucidated: direct nucleophilic displacement, as well as β-elimination followed by Michael addition. Furthermore, β-keto ester and β-keto ketone products 18k,18m, and 18i were converted to prolines and pyrazole amino acids.Key words: glutamate, amino acid, cyclic sulfamidate, proline.

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