Reactions of nitro sugars. XVII. Koenigs–Knorr syntheses

1970 ◽  
Vol 48 (8) ◽  
pp. 1302-1308 ◽  
Author(s):  
Hans H. Baer ◽  
Werner Rank ◽  
Frank Kienzle
Keyword(s):  
Benzyl Alcohol ◽  
Acetyl Derivative ◽  
Pure Form ◽  
Free Sugar ◽  
Acetyl Group ◽  
Group Migration ◽  
Derivatives Of

Starting from methyl 3-deoxy-3-nitro-β-D-glucopyranoside (1), the free sugar 3-deoxy-3-nitro-α-D-glucopyranose (2), its tetraacetate (3), and 2,4,6-tri-O-acetyl-3-deoxy-3-nitro-α-D-glucopyranosyl bromide (4) were prepared. Another sequence of reactions commencing with 1 gave the 6-O-trityl (6), the 2,4-di-O-acetyl-6-O-trityl (7), the 2,4,6-tri-O-acetyl (8), and the 2,6-di-O-acetyl (10) derivatives of 1, whereas the 2,4-di-O-acetyl derivative (9) could not be isolated in pure form because of acetyl group migration. Reaction of the bromide 4 with water, methanol, and benzyl alcohol, respectively, led to 2,4,6-tri-O-acetyl-3-deoxy-3-nitro-β-D-glucopyranose (5) and the corresponding methyl and benzyl β-D-glycosides (8 and 11). Condensation of 4 with 1,2,3,4-tetra-O-acetyl-β-D-glucopyranose (12), and condensation of tetra-O-acetyl-α-D-glucopyranosyl bromide (14) with the trityl compound 6, furnished derivatives of gentiobiose having a deoxynitro function at C-3′ (13) and C-3 (15), respectively.

Kinetics and mechanism of rearrangement and methanolysis of acylphenylthioureas

1985 ◽  
Vol 50 (3) ◽  
pp. 766-778 ◽  
Author(s):  
Jaromír Kaválek ◽  
Josef Jirman ◽  
Vojeslav Štěrba
Keyword(s):  
Acetyl Derivative ◽  
Base Catalysis ◽  
Methyl Group ◽  
Phenyl Derivative ◽  
Benzoyl Group ◽  
Order Of Magnitude ◽  
Acetyl Group ◽  
Methyl Derivatives ◽  
Derivatives Of ◽  
Acyl Derivatives

S-Acyl-1-phenylthioureas and their 3-methyl derivatives are rearranged to 1-acyl derivatives of thiourea in methanolic solution. The rearrangement of the 1-acyl-1-phenyl derivative to the thermodynamically more stable 3-acyl derivative is subject to specific base catalysis. The rearrangement of acetyl group is about 2 orders of magnitude slower than that of benzoyl group. 1-Acetyl-l-phenylthiourea undergoes base-catalyzed methanolysis (giving phenylthiourea and methyl acetate) instead of the rearrangement. The methanolysis rates of l-acyl-3-phenylthioureas and their N-methyl derivatives have been measured. The acetylthioureas react at most 3x faster than the benzoyl derivatives. The methyl group at the nitrogen adjacent to acyl group accelerates the solvolysis by almost 2 orders of magnitude; the methyl group at the other nitrogen atom retards the solvolysis by almost 1 order of magnitude. Replacement of hydrogen atom by methyl group at the phenyl-substituted nitrogen increases acidity of the phenylacetylthiourea by 2 orders of magnitude. The same replacement at the benzoyl-substituted nitrogen increases the acidity by 3 orders of magnitude, the increase in the case of the acetyl derivative being as large as 4 orders of magnitude.

The role of secondary alcoholic groups of D-galacturonan in its degradation with exo-D-galacturonanase

1980 ◽  
Vol 45 (2) ◽  
pp. 427-434 ◽  
Author(s):  
Kveta Heinrichová ◽  
Rudolf Kohn
Keyword(s):  
Acetyl Derivative ◽  
Competitive Inhibitor ◽  
Hydroxyl Groups ◽  
Pectic Acid ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
The Individual ◽  
Degradation Degree ◽  
Derivatives Of

The effect of exo-D-galacturonanase from carrot on O-acetyl derivatives of pectic acid of variousacetylation degree was studied. Substitution of hydroxyl groups at C(2) and C(3) of D-galactopyranuronic acid units influences the initial rate of degradation, degree of degradation and its maximum rate, the differences being found also in the time of limit degradations of the individual O-acetyl derivatives. Value of the apparent Michaelis constant increases with increase of substitution and value of Vmax changes. O-Acetyl derivatives act as a competitive inhibitor of degradation of D-galacturonan. The extent of the inhibition effect depends on the degree of substitution. The only product of enzymic reaction is D-galactopyranuronic acid, what indicates that no degradation of the terminal substituted unit of O-acetyl derivative of pectic acid takes place. Substitution of hydroxyl groups influences the affinity of the enzyme towards the modified substrate. The results let us presume that hydroxyl groups at C(2) and C(3) of galacturonic unit of pectic acid are essential for formation of the enzyme-substrate complex.

scholarly journals Kinetic Studies of Acetyl Group Migration between the Saccharide Units in an Oligomannoside Trisaccharide Model Compound and a Native Galactoglucomannan Polysaccharide

ChemBioChem ◽  
2021 ◽  
Author(s):  
Robert Lassfolk ◽  
Sara Bertuzzi ◽  
Ana Ardá ◽  
Johan Wärnå ◽  
Jesús Jiménez‐Barbero ◽  
...  
Keyword(s):  
Model Compound ◽  
Kinetic Studies ◽  
Acetyl Group ◽  
Group Migration

scholarly journals Self-Supporting Hydrogels Based on Fmoc-Derivatized Cationic Hexapeptides for Potential Biomedical Applications

Biomedicines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 678
Author(s):  
Carlo Diaferia ◽  
Elisabetta Rosa ◽  
Enrico Gallo ◽  
Giovanni Smaldone ◽  
Mariano Stornaiuolo ◽  
...  
Keyword(s):  
Biomedical Applications ◽  
Supporting Cell ◽  
Diagnostic Tools ◽  
Cationic Peptides ◽  
Protecting Group ◽  
Synthetic Hydrogel ◽  
Acetyl Group ◽  
Biophysical Techniques ◽  
Fmoc Protecting Group ◽  
Derivatives Of

Peptide-based hydrogels (PHGs) are biocompatible materials suitable for biological, biomedical, and biotechnological applications, such as drug delivery and diagnostic tools for imaging. Recently, a novel class of synthetic hydrogel-forming amphiphilic cationic peptides (referred to as series K), containing an aliphatic region and a Lys residue, was proposed as a scaffold for bioprinting applications. Here, we report the synthesis of six analogues of the series K, in which the acetyl group at the N-terminus is replaced by aromatic portions, such as the Fmoc protecting group or the Fmoc-FF hydrogelator. The tendency of all peptides to self-assemble and to gel in aqueous solution was investigated using a set of biophysical techniques. The structural characterization pointed out that only the Fmoc-derivatives of series K keep their capability to gel. Among them, Fmoc-K3 hydrogel, which is the more rigid one (G’ = 2526 Pa), acts as potential material for tissue engineering, fully supporting cell adhesion, survival, and duplication. These results describe a gelification process, allowed only by the correct balancing among aggregation forces within the peptide sequences (e.g., van der Waals, hydrogen bonding, and π–π stacking).

scholarly journals Acetyl Group Migration across the Saccharide Units in Oligomannoside Model Compound

2018 ◽  
Vol 141 (4) ◽  
pp. 1646-1654 ◽  
Author(s):  
Robert Lassfolk ◽  
Jani Rahkila ◽  
Mikael P. Johansson ◽  
Filip S. Ekholm ◽  
Johan Wärnå ◽  
...  
Keyword(s):  
Model Compound ◽  
Acetyl Group ◽  
Group Migration

Acetal Formation Facilitated in 2-Hydroxyaryl Aldehydes by Intramolecular Acyl Group Transfer

1986 ◽  
Vol 39 (11) ◽  
pp. 1747 ◽  
Author(s):  
AJ Liepa ◽  
AJ Liepa ◽  
TC Morton ◽  
TC Morton
Keyword(s):  
Acyl Transfer ◽  
Reaction Conditions ◽  
Group Transfer ◽  
Acetyl Group ◽  
Derivatives Of ◽  
Acyl Derivatives ◽  
Mechanism Of The Reaction

Convenient preparations of synthetically useful acetals, a dithioacetal and an oxathiolan from the 2-acyl derivatives of 2-hydroxyaryl aldehydes under basic conditions are described. The mildness of the reaction conditions is illustrated by the formation of an ethoxycarbonyl -substituted dioxolan . The reaction is dependent upon an intramolecular acetyl group transfer and the mechanism of the reaction is discussed. Some broader implications of this type of acyl transfer are discussed.

scholarly journals The Synthesis of the Locating Substitution Derivatives of Chitosan by Click Reaction at the 6-Position of Chitin

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Yu Chen ◽  
Yanchun Ye ◽  
Yanyan Jing ◽  
YuanYuan Gao ◽  
Yanwen Guo ◽  
...  
Keyword(s):  
Nucleophilic Substitution ◽  
High Efficiency ◽  
Click Reaction ◽  
Macrocyclic Compound ◽  
Optimum Conditions ◽  
Structures And Properties ◽  
Acetyl Group ◽  
Novel Method ◽  
Derivatives Of

A novel method to prepare the macrocyclic compound locating substitution derivatives of chitosan was investigated, by using cyclodextrin as the model of macrocyclic compound. The method combines the advantages of activated 6-OH of chitin and high efficiency of click reaction. Chitin C6-OHp-toluenesulfonate (CTN-6-OTs) was generated and subsequently transferred to chitin C6-N3via nucleophilic substitution. Afterwards,β-cyclodextrin was immobilized at 6-OH of chitin via click reaction to afford CTN-6-CD. Ultimately, CTS-6-CD was obtained by removing the acetyl group of chitin unit. The structures and properties of these products were characterized by FTIR, TG, and XRD, respectively. It was found that CTN-6-CD synthesized at the optimum conditions has an immobilized loading of1.6126×10-4 mol/g and that of the corresponding CTS-6-CD, generated by removal of the acetyl group, was1.6891×10-4 mol/g.

THE HYDROLYSIS OF p-ACETOXYPHENYLETHYLAMINES BY INSECT CHOLINESTERASE

1958 ◽  
Vol 36 (1) ◽  
pp. 145-152
Author(s):  
L. S. Wolfe ◽  
G. D. Thorn
Keyword(s):  
Human Serum ◽  
Carbonyl Oxygen ◽  
Rectus Abdominis ◽  
Hydrolysis Rate ◽  
Rectus Abdominis Muscle ◽  
Oxygen Separation ◽  
Bovine Erythrocyte ◽  
Acetyl Group ◽  
Hydrolysis Of ◽  
Derivatives Of

The synthesis of the acetyl derivatives of tyramine and hordenine is described. The O-monoacetyl derivatives are hydrolyzed at significant rates by bovine erythrocyte cholinesterase, human serum, and fly head cholinesterase despite a nitrogen to carbonyl oxygen separation approximately twice that of acetylcholine. The pS-activity relationships, when O-acetyltyramine and acetylcholine were substrates for fly head cholinesterase, were similar, but the hydrolysis rate of O-acetyltyramine was much higher than that of acetylcholine. N-Acetylation of the O-acetyl compounds reduced the hydrolysis rate. None of the cholinesterases removed the acetyl group attached to nitrogen. The pI-activity relationships with the inhibitors Nu-683, Nu-1250, TEPP, and eserine showed that the hydrolysis of p-acetoxyphenylethylamine derivatives and acetylcholine by fly head preparations was accomplished by the same cholinesterase and not by aromatic or aliesterases. O-Acetylation of hordenine methiodide destroyed its nicotinelike action on frog rectus abdominis muscle.

scholarly journals Anticancer and Anti-Inflammatory Activities of Some New Pyrazolo[3,4-b]pyrazines

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2657
Author(s):  
Hussein El-Kashef ◽  
Talaat El-Emary ◽  
Pierre Verhaeghe ◽  
Patrice Vanelle ◽  
Maha Samy
Keyword(s):  
Breast Cancer ◽  
Cell Line ◽  
Cancer Cell Line ◽  
Acetyl Derivative ◽  
The Other ◽  
Reference Drug ◽  
Anti Inflammatory ◽  
Sar Study ◽  
Derivatives Of ◽  
Mcf 7

New derivatives of pyrazolo[3,4-b]pyrazines and related heterocycles were synthesized using 5-amino-3-methyl-4-nitroso-1-phenyl-pyrazole (1) as a starting material. The 5-acetyl derivative 15 was shown to be a useful key intermediate for the synthesis of several derivatives of pyrazolopyrazines. Some of the prepared compounds were evaluated for their anti-inflammatory and anti-breast cancer MCF-7 cell line activities. SAR study showed that compounds 15 and 29 exhibited remarkable anti-inflammatory activity, where 15 showed the same activity as that of the reference drug indomethacin. On the other hand, compounds 25i, 25j showed very significant inhibitory activity (p < 0.001) against MCF-7 breast cancer cell line.

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