Further studies of the diazo coupling reactions of pyrimidines

1983 ◽  
Vol 36 (8) ◽  
pp. 1659 ◽  
Author(s):  
DT Hurst
Keyword(s):  
Coupling Reactions ◽  
Methyl Substituent ◽  
Diazo Coupling ◽  
Acetyl Group ◽  
Derivatives Of

6-Arylazo derivatives of the following pyrimidines have been obtained: 2-acetamido-4,5-dihydroxy-, 4-amino-2,5-dihydroxy-, 2,4-diamino-5-hydroxy- and 4-amino-5-hydroxy-2-methyl-pyrimidine. However, some 5-substituted pyrimidines having other electron-releasing groups failed to undergo diazo coupling. 2,4-Dihydroxypyrimidin-5-yl acetate and 2-acetamido-4-hydroxypyrimidin-5-yl acetate lost the 5-acetyl group during the introduction of the arylazo group into the 6-position. However, 2-hydroxy-4,6-dimethylpyrimidin-5-yl acetate undergoes diazo coupling at the 4(6)-methyl substituent without loss of the 5-acetyl group. The mechanisms for these diazo couplings are discussed.

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).

Directing Bromination of Piperazine-2,5-diones

1995 ◽  
Vol 48 (7) ◽  
pp. 1379 ◽  
Author(s):  
TW Badran ◽  
CLL Chai ◽  
CJ Easton ◽  
JB Harper ◽  
DM Page
Keyword(s):  
Free Radical ◽  
Methyl Substituent ◽  
Radical Bromination ◽  
Acetyl Group

From intermolecular and intramolecular competition experiments, it has been established that, by comparison with an N-methyl substituent, an N-acetyl group deactivates glycine residues in piperazine-2,5-diones towards free-radical bromination. Combined with the ease of introduction and removal of N-acetyl substituents, the deactivating effect provides a method for regiocontrolled functionalization of these compounds.

scholarly journals New Diazo Coupling Reactions for Visible Spectrophotometric Determination of Alfuzosin in Pharmaceutical Preparations

2007 ◽  
Vol 4 (4) ◽  
pp. 496-501 ◽  
Author(s):  
M. Vamsi Krishna ◽  
D. Gowri Sankar
Keyword(s):  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Basic Medium ◽  
Coupling Reactions ◽  
Acetyl Acetone ◽  
Diazo Coupling ◽  
Optimum Reaction ◽  
Diazonium Ion

Simple, rapid and sensitive spectrophotometric procedures were developed for the analysis of Alfuzosin hydrochloride (AFZ) in pure form as well as in pharmaceutical formulations. The methods are based on the reaction of AFZ with nitrite in acid medium to form diazonium ion, which is coupled with ethoxyethylenemaleic ester (Method A) or ethylcyanoacetate (Method B) or acetyl acetone (method C) in basic medium to form azo dyes, showing absorption maxima at 440, 465 and 490 nm respectively. Beer’s law is obeyed in the concentration of 4-20 μg/mL of AFZ for methods A, B and 3-15 μg/mL of AFZ for method C. The molar absorptivity and sandell’s sensitivity of AFZ- ethoxyethylenemaleic ester, AFZ- ethylcyanoacetate and AFZ-acetyl acetone are1.90 × 104, 0.022; 1.93 × 104, 0.021 and 2.67 × 104L mole-1cm-1, 0.015 μg cm-2respectively. The optimum reaction conditions and other analytical parameters were evaluated. The methods were successfully applied to the determination of AFZ in pharmaceutical formulations.

scholarly journals Synthesis and antitrypanosomal activities of a series of 7-deaza-5'-noraristeromycin derivatives with variations in the cyclopentyl ring substituents.

1997 ◽  
Vol 41 (8) ◽  
pp. 1658-1661 ◽  
Author(s):  
K L Seley ◽  
S W Schneller ◽  
D Rattendi ◽  
S Lane ◽  
C J Bacchi
Keyword(s):  
Methyl Substituent ◽  
Prototype Structure ◽  
Growth Activity ◽  
Derivatives Of ◽  
Related Compounds

Previous work in our laboratories has suggested that (+)-5'-nor-7-deazaaristeromycin (compound 1) may represent a prototype structure for a series of compounds with significant antitrypanosomal activities. To test this possibility, a series of derivatives of compound 1 with changes in the cyclopentyl substituents (compounds 3 to 10) have been studied. Although some growth activity was obtained with the L-like compound 5, related compounds 3 and 7 had little or no activity below 100 microM. D-like compounds 4 and 6 showed some activity at or below 100 microM, but the most interesting finding was that both the D- and L-like compounds having a methyl substituent on the 4' position were most active.

scholarly journals Synthesis of 4-Alkyl-4H-1,2,4-triazole Derivatives by Suzuki Cross-coupling Reactions and Their Luminescence Properties

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 652 ◽  
Author(s):  
Monika Olesiejuk ◽  
Agnieszka Kudelko ◽  
Marcin Swiatkowski ◽  
Rafal Kruszynski
Keyword(s):  
Ionic Liquids ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Boronic Acids ◽  
Luminescence Properties ◽  
Coupling Reactions ◽  
Triazole Derivatives ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Derivatives Of

New derivatives of 4-alkyl-3,5-diaryl-4H-1,2,4-triazole were synthesized utilizing the Suzuki cross-coupling reaction. The presented methodology comprises of the preparation of bromine-containing 4-alkyl-4H-1,2,4-triazoles and their coupling with different commercially available boronic acids in the presence of ionic liquids or in conventional solvents. The obtained compounds were tested for their luminescence properties.

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.

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