scholarly journals Microwave-Assisted Synthesis of Mono- and Disubstituted 4-Hydroxyacetophenone Derivatives via Mannich Reaction: Synthesis, XRD and HS-Analysis

Molecules ◽  
2019 ◽  
Vol 24 (3) ◽  
pp. 590 ◽  
Author(s):  
Ghadah Aljohani ◽  
Musa Said ◽  
Dieter Lentz ◽  
Norazah Basar ◽  
Arwa Albar ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Chair Conformation ◽  
Mannich Bases ◽  
Secondary Amines ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted ◽  
Regioselective Substitution ◽  
Intramolecular Hydrogen ◽  
Methyl Phenyl

An efficient microwave-assisted one-step synthetic route toward Mannich bases is developed from 4-hydroxyacetophenone and different secondary amines in quantitative yields, via a regioselective substitution reaction. The reaction takes a short time and is non-catalyzed and reproducible on a gram scale. The environmentally benign methodology provides a novel alternative, to the conventional methodologies, for the synthesis of mono- and disubstituted Mannich bases of 4-hydroxyacetophenone. All compounds were well-characterized by FT-IR, 1H NMR, 13C NMR, and mass spectrometry. The structures of 1-{4-hydroxy-3-[(morpholin-4-yl)methyl]phenyl}ethan-1-one (2a) and 1-{4-hydroxy-3-[(pyrrolidin-1-yl)methyl]phenyl}ethan-1-one (3a) were determined by single crystal X-ray crystallography. Compound 2a and 3a crystallize in monoclinic, P21/n, and orthorhombic, Pbca, respectively. The most characteristic features of the molecular structure of 2a is that the morpholine fragment adopts a chair conformation with strong intramolecular hydrogen bonding. Compound 3a exhibits intermolecular hydrogen bonding, too. Furthermore, the computed Hirshfeld surface analysis confirms H-bonds and π–π stack interactions obtained by XRD packing analyses.

Intramolecular Hydrogen Bonding (PO--H) Stabilizes the Chair Conformation of Six-Membered Ring Phosphates

2005 ◽  
Vol 70 (18) ◽  
pp. 7107-7113 ◽  
Author(s):  
Silvano Cruz-Gregorio ◽  
Mario Sanchez ◽  
Angel Clara-Sosa ◽  
Sylvain Bèrnes ◽  
Leticia Quintero ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Intramolecular Hydrogen Bonding ◽  
Chair Conformation ◽  
Membered Ring ◽  
Intramolecular Hydrogen

scholarly journals Intramolecular Hydrogen Bonds in Selected Aromatic Compounds: Recent Developments

Catalysts ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 909
Author(s):  
Aneta Jezierska ◽  
Peter M. Tolstoy ◽  
Jarosław J. Panek ◽  
Aleksander Filarowski
Keyword(s):  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Aromatic Compounds ◽  
Mannich Base ◽  
Intramolecular Hydrogen Bonding ◽  
Mannich Bases ◽  
Intramolecular Hydrogen Bonds ◽  
Recent Developments ◽  
Physicochemical Features ◽  
Intramolecular Hydrogen

A review of intramolecular hydrogen bonding in ortho-hydroxyaryl Schiff bases, ortho-hydroxyaryl Mannich bases, dipyrrins, ortho-hydroxyaryl ketones, ortho-hydroxyaryl amides, and 4-Bora-3a,4a-diaza-s-indacene (BODIPY) dyes with tautomeric sensors as substituents is presented in this paper. Ortho-hydroxy Schiff and Mannich base derivatives are known as model molecules for analysing the properties of intramolecular hydrogen bonding. The compounds under discussion possess physicochemical features modulated by the presence of strong intramolecular hydrogen bonds. The equilibrium between intra- and inter-molecular hydrogen bonds in BODIPY is discussed. Therefore, the summary can serve as a knowledge compendium of the influence of the hydrogen bond on the molecular properties of aromatic compounds.

Spectral properties and intramolecular hydrogen bonding in 1-methyl(phenyl)-4(5)-substituted 6-oxo-1H-pyridazin-4(5)-ols

1980 ◽  
Vol 45 (1) ◽  
pp. 127-134 ◽  
Author(s):  
Štefan Kováč ◽  
Václav Konečný
Keyword(s):  
Hydrogen Bonding ◽  
Spectral Data ◽  
Spectral Properties ◽  
Intramolecular Hydrogen Bonding ◽  
H Nmr ◽  
Substituent Constants ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bondings ◽  
Methyl Phenyl

Infrared, ultraviolet and 1H-NMR spectral data of 53 1-methyl(phenyl)-4(5)-substituted 6-oxo-1H-pyridazin-4(5)-ols are listed. Intramolecular hydrogen bondings are discussed; relatively strong hydrogen bondings OH...S were found, which are comparable in terms of strength with those of OH...O=C. Wavenumbers of ν(C=O) and ν(O-H) bands linearly correlated with substituent constants σ*, σR and σF.

Microwave-assisted synthesis of novel Mannich base and conazole derivatives containing biological avtive pharmacological groups

2020 ◽  
Vol 17 ◽  
Author(s):  
Yıldız Uygun Cebeci ◽  
Sule Ceylan ◽  
Neslihan Demirbas ◽  
Şengül Alpay Karaoğlu
Keyword(s):  
Antimicrobial Activity ◽  
Active Sites ◽  
Sodium Ethoxide ◽  
Mannich Bases ◽  
Biologically Active ◽  
Secondary Amines ◽  
Microwave Assisted Synthesis ◽  
Standard Drug ◽  
Triazole Derivatives ◽  
Microwave Assisted

Background: The aim of this study is to synthesize new Mannich bases and conazol derivatives with biological activity by the microwave-assisted method. Introduction: 1,2,4-Triazole-3-one (3) acquired from tryptamine was transformed to the corresponding carbox(thio)amides (6a-c) via several steps. Compounds, 6a-c, were refluxed with sodium hydroxide to yield 1,2,4-triazole derivatives (7a-c). Compounds 3 and 7a-c on treatment with different heterocyclic secondary amines in an ambiance with formaldehyde afforded the Mannich bases 8-15 having diverse pharmacophore units with biologically active sites. The reaction of compound 3 and 2-bromo-1-(4-chlorophenyl) ethanone in the presence of sodium ethoxide gave the corresponding product yielded the corresponding 2-substituted-1,2,4-triazole-3-one, 16, which was reduced to 1,2,4-triazoles (17). Synthesis of compounds 18, 19, and 20 were carried out starting from compounds 17 with 4-chlorobenzyl chloride (for 18), 2,4- dichlorobenzyl chloride (for 19), and 2,6-dichlorobenzyl chloride (for 20). Method: The conventional technique was utilized for the synthesis of compounds, 3-7, and microwave-assisted technique for the compounds, 8-20. That is, green chemistry techniques were applied during these reactions. The structures molecules were elucidated on the foundation of 1H NMR, 13C NMR, FT-IR, EI-MS methods, and elemental analysis. Novel synthesized molecules were investigated for their antimicrobial activity using MIC (minimum inhibitory concentration) method. Results and Discussion: Aminoalkylation of triazole derivatives 3 and 7a–c with fluoroquinolones such as ciprofloxacin and norfloxacin provided an enhancement to the bioactivity of Mannich bases 8-11 against the tested microorganisms. The MIC values ranged between <0.24 and 3.9 μg/mL”. Moreover, molecules 10 and 11 have more effective on M. smegmatis than the other compounds by the MIC values of <1 μg/mL. They have shown very good antituberculosis activity. Conclusion: Most of the synthesized structures were observed to have excellent antimicrobial activity against most microorganisms taken into account. These molecules have activity better than the standard drug ampicillin and streptomycin.

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