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.

REACTIONS OF NITRO SUGARS: I. SOME BENZYLIDENE AND ACYL DERIVATIVES OF METHYL 3-DEOXY-3-NITRO-D-HEXOPYRANOSIDES

1965 ◽  
Vol 43 (6) ◽  
pp. 1829-1834 ◽  
Author(s):  
Hans Helmut Baer ◽  
Frank Kienzle ◽  
Thomas Neilson
Keyword(s):  
Acetic Acid ◽  
Reaction Conditions ◽  
Derivatives Of ◽  
Acyl Derivatives

The 4,6-O-benzylidene derivatives VII, VIII, and XVII of methyl 3-deoxy-3-nitro-β-D-mannopyranoside, -β-D-galactopyranoside, and -α-D-glucopyranoside, respectively, were prepared. Acetylation of the β-D-manno derivative (VII) led, depending upon the reaction conditions, to its 2-O-acetate (IX) and, by way of an unexpected epimerization, to the 2-O-acetate (V) of the corresponding β-D-gluco isomer. There is evidence that this epimerization proceeds through methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-β-D-erythro-hexopyranos-2-enide (VI). This nitroolefin was obtained by a Schmidt–Rutz reaction from IX (as earlier from V) and was shown to add acetic acid readily giving V. It also added ethanol producing a 2-O-ethyl glycoside (XII). Acetylation of the galacto derivative (VIII) did not afford an acetate but proceeded with dehydration yielding methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-β-D-thero-hexopyranos-2-enide (X).A number of further derivatives of methyl 3-deoxy-3-nitro-β-D-glucopyranoside were prepared, viz., the 2-O-acetyl (XI), 2-deoxy-6-O-tosyl (XIV), and 2,6-dideoxy-6-iodo (XV) derivatives.

scholarly journals Useful access to enantiomerically pure protected inositols from carbohydrates: the aldohexos-5-uloses route

2016 ◽  
Vol 12 ◽  
pp. 2343-2350 ◽  
Author(s):  
Felicia D’Andrea ◽  
Giorgio Catelani ◽  
Lorenzo Guazzelli ◽  
Venerando Pistarà
Keyword(s):  
Aldol Condensation ◽  
Biomimetic Synthesis ◽  
Protecting Groups ◽  
Reaction Conditions ◽  
Enantiomerically Pure ◽  
Selective Protection ◽  
Inductive Effects ◽  
State Models ◽  
Derivatives Of ◽  
Mechanism Of The Reaction

The intramolecular aldol condensation of aldohexos-5-ulose derivatives of the D-xylo and L-ribo stereoseries has been studied. Only one of the four possible inososes was isolated from both stereoseries in reasonable yields (30–38%). The results obtained, together with the previous findings for the L-arabino and L-lyxo stereoseries, allowed for the rationalisation of a mechanism of the reaction based on open-transition-state models and electron-withdrawing inductive effects. Complementary reductions of the intermediate inososes were possible by changing the reaction conditions, and two isomeric inositol derivatives were obtained with complete stereoselection from each inosose. The presented approach permits us to control the configuration of three out of the six stereocentres of the inositol frame and gives access to seven of the nine inositols. Noteworthy, for the D-xylo derivative, the two-step sequence (condensation followed by reduction with NaBH(OAc)3) represents the biomimetic synthesis of myo-inositol. Furthermore, the sugar-based pathway leads directly to enantiomerically pure selectively protected inositols and does not require any desymmetrisation procedure which is needed when myo-inositol and other achiral precursors are employed as starting materials. As an example of application of the method, the indirect selective protection of secondary inositols’ hydroxy functions, by placing specific protecting groups on the aldohexos-5-ulose precursor has been presented.

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.

Cleavage of the Epimines of 1,6-Anhydrohexoses with Fluoride Anion

2005 ◽  
Vol 70 (12) ◽  
pp. 2075-2085 ◽  
Author(s):  
Jiří Kroutil ◽  
Klára Jeništová
Keyword(s):  
Fluoride Anion ◽  
Ring Cleavage ◽  
Protecting Group ◽  
Reaction Conditions ◽  
Aziridine Ring ◽  
Cleavage Reactions ◽  
Derivatives Of ◽  
Fluoro Derivatives

Aziridine ring cleavage reactions of five N-nosylepimines (2-6) having D-talo, D-galacto, D-manno, and D-allo configurations with potassium hydrogendifluoride under various reaction conditions have been performed. The cleavage regioselectively afforded diaxial isomers of vicinal amino-fluoro derivatives of 1,6-anhydro-β-D-gluco- and mannopyranose 7-11 in 51-94% yields. Removal of 2-nitrobenzenesulfonyl protecting group with benzenethiol has been attempted in the case of compound 10.

scholarly journals Synthesis, Antiproliferative Activity and Radical Scavenging Ability of 5-O-Acyl Derivatives of Quercetin

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1608
Author(s):  
Stephen Lo ◽  
Euphemia Leung ◽  
Bruno Fedrizzi ◽  
David Barker
Keyword(s):  
Antiproliferative Activity ◽  
Biological Activities ◽  
Radical Scavenging Activity ◽  
Radical Scavenging ◽  
Breast Cancer Cell Lines ◽  
Scavenging Activity ◽  
Plant Materials ◽  
Wide Range ◽  
Derivatives Of ◽  
Acyl Derivatives

Quercetin is a flavonoid that is found in many plant materials, including commonly eaten fruits and vegetables. The compound is well known for its wide range of biological activities. In this study, 5-O-acyl derivatives of quercetin were synthesised and assessed for their antiproliferative activity against the HCT116 colon cancer and MDA-MB-231 breast cancer cell lines; and their radical scavenging activity against the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical species. Four derivatives were found to have improved the antiproliferative activity compared to quercetin whilst retaining radical scavenging activity.

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).

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