THE GAS–LIQUID PARTITION CHROMATOGRAPHY OF CARBOHYDRATE DERIVATIVES: PART III. THE SEPARATION OF AMINO GLYCOSE DERIVATIVES AND OF CARBOHYDRATE ACETAL AND KETAL DERIVATIVES

1962 ◽  
Vol 40 (8) ◽  
pp. 1559-1563 ◽  
Author(s):  
H. G. Jones ◽  
J. K. N. Jones ◽  
M. B. Perry
Keyword(s):  
Chromatographic Method ◽  
Hydroxyl Groups ◽  
Partition Chromatography ◽  
Free Hydroxyl

Gas–liquid partition chromatography has been used to separate the anomeric acetates of 2-amino-2-deoxy-D-glucopyranose (D-glucosamine) and of 2-amino-2-deoxy-D-galactopyranose (D-galactosamine) and also their fully acetylated reduction products, 2-acetamido-2-deoxy-1,3,4,5,6-penta-O-acetyl-D-glucitol and 2-acetamido-2-deoxy-1,3,4,5,6-penta-O-acetyl-D-galactitol. The gas–liquid partition chromatographic method has also been successfully applied to the separation of unsubstituted carbohydrate acetal and ketal derivatives and to those derivatives in which the free hydroxyl groups have been substituted by O-acetyl, O-benzoyl, O-benzyl, carbonate, O-methanesulphonyl, O-methyl, and O-toluene-p-sulphonyl groups.

Enzymic deacylation of esterified mono- and disaccharides. 3. The location of acetylated positions in partially acetylated sugars

1969 ◽  
Vol 47 (5) ◽  
pp. 845-853 ◽  
Author(s):  
A. L. Fink ◽  
G. W. Hay
Keyword(s):  
Nitric Acid ◽  
Hydroxyl Groups ◽  
Partition Chromatography ◽  
Reaction Sequence ◽  
Initial Product ◽  
Nitrate Ester ◽  
Product Identification ◽  
Free Hydroxyl ◽  
Fuming Nitric Acid ◽  
Acetyl Migration

The nitrate ester, formed by reaction with fuming nitric acid in acetic anhydride at 0 °C, was suitable to block free hydroxyl groups in partially acetylated sugars without acetyl migration. This allowed the acetylated positions in partially acetylated mono- and disaccharides to be located by the reaction sequence: nitration, deacetylation, methylation, de-nitration, disaccharide hydrolysis and methyl glycosylation (initial product identification by paper partition chromatography), acetylation, and analysis of the products by gas-liquid partition chromatography. D-Glucose, penta-O-acetyl-D-glucopyranose, and 2,3-di-O-acetyl-β-D-glucopyranose were used as test compounds in the evaluation of this scheme.

The synthesis and structure of silica-supported bis(h5-cyclopentadienyl)dichlorotitanium(IV) complexes

1986 ◽  
Vol 51 (7) ◽  
pp. 1430-1438 ◽  
Author(s):  
Alena Reissová ◽  
Zdeněk Bastl ◽  
Martin Čapka
Keyword(s):  
Free Surface ◽  
Hydroxyl Groups ◽  
Titanium Complex ◽  
Surface Hydroxyl ◽  
Surface Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Cyclopentadienyl Anion

The title complexes have been obtained by functionalization of silica with cyclopentadienylsilanes of the type Rx(CH3)3 - xSi(CH2)nC5H5 (x = 1-3, n = 0, 1, 3), trimethylsilylation of free surface hydroxyl groups, transformation of the bonded cyclopentadienyl group to the cyclopentadienyl anion, followed by coordination of (h5-cyclopentadienyl)trichlorotitanium. The effects of single steps of the above immobilization on texture of the support, the number of free hydroxyl groups, the coverage of the surface by cyclopentadienyl groups and the degree of their utilization in anchoring the titanium complex have been investigated. ESCA study has shown that the above anchoring leads to formation of the silica-supported bis(h5-cyclopentadienyl)dichlorotitanium(IV) complex.

Substitutional and solvation effects on conformational equilibria. Effects on the interaction between opposing axial oxygen atoms

1969 ◽  
Vol 47 (23) ◽  
pp. 4441-4446 ◽  
Author(s):  
R. U. Lemieux ◽  
A. A. Pavia
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Hydrogen Bonding ◽  
Magnetic Resonance ◽  
Hydroxyl Groups ◽  
Evidence Based ◽  
Electrostatic Repulsion ◽  
Hydrogen Bridge ◽  
Conformational Equilibria ◽  
Free Hydroxyl ◽  
Oxygen Atoms

Evidence based both on nuclear magnetic resonance and rotation data primarily obtained from methyl 3-deoxy-β-L-erythro-pentopyranoside and a number of its derivatives is interpreted to show that the electrostatic repulsion between the oxygen atoms at the 2 and 4 positions is substantially less when these oxygens are linked to acyl groups than when in the form of either methyl ethers or as hydroxyl groups hydrogen bonded to solvent. Also, experimental evidence is presented which requires the hydrogen bridge between two axially disposed hydroxyl groups to be substantially strengthened by hydrogen bonding of the free hydroxyl by solvent.

Light-Mediated Cross-Coupling of Anomeric Trifluoroborates

2021 ◽  
Author(s):  
Eric Miller ◽  
Maciej Walczak
Keyword(s):  
Cross Coupling ◽  
Hydroxyl Groups ◽  
Anomeric Effect ◽  
Computational Studies ◽  
Carbohydrate Chemistry ◽  
New Class ◽  
Free Hydroxyl ◽  
Anomeric Carbon ◽  
Stereoselective Reactions

Stereoselective reactions at the anomeric carbon constitute the cornerstone of preparative carbohydrate chemistry. Here, we report the synthesis of axial C1 trifluoroborates and stereoselective C-arylation and etherification reactions under photoredox conditions. These reactions are characterized by high anomeric selectivities for 2-deoxysugars and broad substrate scope (24 examples), including disaccharides and trifluoroborates with free hydroxyl groups. Computational studies show that high axial selectivities for these reactions originate from a combination of kinetic anomeric effect of the intermediate C1 radical and stereoelectronic stabilization of Ni(III) through the metallo-anomeric effect. Taken together, this new class of carbohydrate reagents adds the palette of anomeric nucleophile reagents suitable for efficient installation C-C and Cheteroatom bonds.

scholarly journals Synthesis and Characterizations of Dipeptide Derivative of Gentamicin

2019 ◽  
Vol 28 (2) ◽  
pp. 73-82
Author(s):  
Oun D. Khudair ◽  
Diar A. Fatih
Keyword(s):  
Acid Chloride ◽  
Solution Method ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Free Hydroxyl ◽  
Ester Linkage ◽  
Amine Groups ◽  
Conventional Solution ◽  
Dipeptide Derivative

Abstract       The target derivative are gentamicin linked with L-Val- L-Ala by an ester linkage. These were synthesized by esterification method, which included the reaction of -OH hydroxyl group on (carbon No.5) of gentamicin with the acid chloride of the corresponding dipeptide, The preparation of new derivative of gentamicin involved protected the primary & secondary amine groups of Gentamicin, by Ethylchloroformate (ECF) to give N-carbomethoxy Gentamicin which was used for further chemical synthesis involving the free hydroxyl groups. Then prepared dipeptide (L-Val- L-Ala) by conventional solution method in present DCC & HoBt then reacted with thionyl chloride to prepared acid chloride of dipeptides, then after, linked by ester linkage to N-protection gentamicin in present pyridine as base, finally deportation the amino group of synthesized compound by using TFAA in present anisole. The characterization of the titled compounds were performed utilizing FTIR spectroscopy, CHNS elemental analysis, and by measurements of their physical properties.  

Structure formation of polyarylates containing free hydroxyl groups in the chain

1965 ◽  
Vol 7 (4) ◽  
pp. 775-781
Author(s):  
V.V. Korshak ◽  
S.V. Vinogradova ◽  
S.A. Siling
Keyword(s):  
Structure Formation ◽  
Hydroxyl Groups ◽  
Free Hydroxyl

Light-Mediated Cross-Coupling of Anomeric Trifluoroborates

2021 ◽  
Author(s):  
Eric Miller ◽  
Maciej Walczak
Keyword(s):  
Cross Coupling ◽  
Hydroxyl Groups ◽  
Anomeric Effect ◽  
Computational Studies ◽  
Carbohydrate Chemistry ◽  
New Class ◽  
Free Hydroxyl ◽  
Anomeric Carbon ◽  
Stereoselective Reactions

Stereoselective reactions at the anomeric carbon constitute the cornerstone of preparative carbohydrate chemistry. Here, we report the synthesis of axial C1 trifluoroborates and stereoselective C-arylation and etherification reactions under photoredox conditions. These reactions are characterized by high anomeric selectivities for 2-deoxysugars and broad substrate scope (24 examples), including disaccharides and trifluoroborates with free hydroxyl groups. Computational studies show that high axial selectivities for these reactions originate from a combination of kinetic anomeric effect of the intermediate C1 radical and stereoelectronic stabilization of Ni(III) through the metallo-anomeric effect. Taken together, this new class of carbohydrate reagents adds the palette of anomeric nucleophile reagents suitable for efficient installation C-C and Cheteroatom bonds.

Zum Mechanismus der Amadori-Umlagerung

1965 ◽  
Vol 20 (1) ◽  
pp. 32-35 ◽  
Author(s):  
D. Palm ◽  
Helmut Simon
Keyword(s):  
Hydroxyl Groups ◽  
Tracer Technique ◽  
Amadori Rearrangement ◽  
Free Hydroxyl

By the tracer technique it is shown that the mechanism of the Amadori - rearrangement which was proposed by MICHEEL and DIJONG is not valid for N-Glycosides with free hydroxyl groups.

scholarly journals Ellagic Acid Derivatives from Syzygium cumini Stem Bark: Investigation of their Antiplasmodial Activity

2009 ◽  
Vol 4 (10) ◽  
pp. 1934578X0900401 ◽  
Author(s):  
Claudia A. Simões-Pires ◽  
Sandra Vargas ◽  
Andrew Marston ◽  
Jean-Robert Ioset ◽  
Marçal Q. Paulo ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Ellagic Acid ◽  
Stem Bark ◽  
Antimalarial Drugs ◽  
Antiplasmodial Activity ◽  
Hydroxyl Groups ◽  
Syzygium Cumini ◽  
Free Hydroxyl ◽  
Ellagic Acid Derivatives

Bioguided fractionation of Syzygium cumini (Myrtaceae) bark decoction for antiplasmodial activity was performed, leading to the isolation of three known ellagic acid derivatives (ellagic acid, ellagic acid 4-O-α-L-2″-acetylrhamnopyranoside, 3-O-methylellagic acid 3′-O-α-L-rhamnopyranoside), as well as the new derivative 3-O-methylellagic acid 3′-O-β-D-glucopyranoside. Activity investigation was based on the reduction of P. falciparum (PfK1) parasitaemia in vitro and the inhibition of β-hematin formation, a known mechanism of action of some antimalarial drugs. Among the investigated ellagic acid derivatives, only ellagic acid was able to reduce P. falciparum parasitaemia in vitro and inhibit β-hematin formation, suggesting that free hydroxyl groups are necessary for activity within this class of compounds.

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