The Synthesis of 3-Acyl-2,3-dihydro-2,2-dimethyl-1,3-thiazoles

Acylation of 2,5-dihydro-2,2-dimethyl-1,3-thiazoles leads to 3-acyl-2,3-dihydro-2,2-dimethyl-1,3-thiazoles as potential starting materials for the total synthesis of racemic cephalosporins.     

Selenium-sulfur analogs. 7. Synthesis and characterization of 4-aralkyl-1,3-selenazoles and -1,3-thiazoles

The diketones 3 and 7 were brominated to give the bromomethyldiketones 4 and 8 which were condensed with selenourea and thiourea to give the corresponding 2-amino-1,3-selenazoles 5a, 9a and 2-amino-1,3-thiazoles 5b, 9b . Reaction with acetic anhydride and benzoic anhydride yielded the 2-acylated derivatives. Biologic evaluation of these compounds indicated some activity as adrenocortical enzyme inhibitors, but significantly less than that of metyropone.     

One-pot synthesis of new 2,4,5-trisubstituted 1,3-thiazoles and 1,3-selenazoles

In this work, we describe the synthesis of new 2,4,5-trisubstituted-1,3-thiazoles and 1,3-selenazole achieved by an easy one-pot four-step procedure. Expected compounds were obtained in good yield from dimethyl cyanodithioimidocarbonate, which was the common starting material for the preparation of all 1,3-thiazoles and 1,3-selenazoles. Chemical diversity was introduced on thiazole and selenazole rings by varying the amines and the activated halides used.     

Synthesis,characterization and antimicrobial evaluation of novel halopyrazole derivatives

Two novel halopyrazole derivatives (3, 5) were synthesized from 5-chloro-3-methyl-1-phenylpyrazole-4-carboxaldehyde (1) using appropriate synthetic routes. Newly synthesized compounds were characterized using elemental analysis, spectral data (IR, ¹H NMR, ¹³C NMR and mass spectrometry) and were evaluated for their in vitro antimicrobial activity. The minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and minimum fungicidal concentration (MFC) were determined for the test compounds as well as for reference standards. The investigation of antimicrobial screening revealed that compounds (3, 5) showed good antibacterial and antifungal activities, respectively.     

Synthesis of novel unsymmetrical coumarinyl-1,4-dihydropyridines

The novel unsymmetrical 3,5-dialkoxycarbonyl-2,6-dimethyl-4-(7′,8′-dimethoxycoumarin-4′-yl)-1,4-dihydropyridines and 5-acetyl-3-alkoxycarbonyl-2,6-dimethyl-4-(7′,8′-dimethoxycoumarin-4′-yl)-1,4-dihydropyridines (coumarinyl-1,4-dihydropyridines) have been synthesized by Knoevenagel condensation of 4-formyl-7,8-dimethoxycoumarin with alkyl acetoacetates in the presence of AlCl₃ followed by cyclization of the resulted Knoevenagel product with other alkyl acetoacetate or acetyl acetone and ammonium acetate. The structure of the intermediate Knoevenagel product and the cyclized unsymmetrical coumarinyl-1,4-dihydropyridines has been established on the basis of their spectral data analysis and single-crystal X-ray diffraction analysis. The observed conformation of the coumarinyl-1,4-dihydropyridines holds the key to promising calcium antagonistic activity of the synthesized coumarinyl-1,4-dihydropyridines.     

Synthesis of novel piperazine tethered benzocycloheptenone hybrids and their antimicrobial evaluation

A new series of benzosuberone-piperazine hybrids 6a to j were designed and synthesized efficiently in good yields and their structures were confirmed by ¹H NMR, ¹³C NMR, ESI-MS and HRMS. The newly synthesized compounds were evaluated for their in vitro antimicrobial activity against Gram positive, Gram negative bacterial strains and a fungal strain. Among the synthesized compounds, compounds 6c , 6d , 6e , 6f , 6g and 6h exhibited potent antibacterial activity with MIC value of 1.9 μg/mL against Gram positive and Gram negative organisms.     

Synthesis of novel thiazol-5-ylpyrimidine derivatives and their antimicrobial evaluation

Novel thiazol-5-ylpyrimidine derivatives were designed and synthesized. The chemical structures of all new synthesized compounds were assigned by studying their elemental analyses and spectral data (FT-IR, ¹HNMR, ¹³C NMR, and MS). The target compounds, 8 and 9a-9d were evaluated for their antimicrobial activity in vitro against gram-positive bacteria, Bacillus subtilis and Staphylococcus aureus, gram-negative bacteria, Salmonella abony and Escherichia coli and fungi, Aspergillus flavus and Fusarium oxysporum. In particular, compounds 9a-9c exhibited moderate to good activity against gram-positive bacteria, S. aureus, gram-negative bacteria, S. abony and fungus, Fusarium oxysporum in comparison with reference drugs.     

Synthesis and characterization of a novel series of unsymmetrical porphyrins

A novel series of unsymmetrical porphyrins with aldehyde group at the terminal of the linkage which connected to meso-phenyl through acylamide bond have been synthesized and structurally characterized by IR,~1H NMR,MS,UV-vis,fluorescence.     

Synthesis and evaluation of some novel tetrahydropyrimidine derivatives as antimicrobial and cytotoxic agents

Starting from the reaction of ethyl cyanoacetate with thiourea and the appropriate aldehydes, a series of new thiopyrimidine derivatives were prepared. Antibacterial evaluation results revealed that compounds 12b, 4c and 11b gave the highest antibacterial activity against all tested bacterial strains. Also, some of the novel compounds were evaluated as cytotoxic agents against liver cancer (HEPG2) cell line. It was noticed that some of the derivatives induced significant growth inhibition with IC₅₀ values (ranged from 6.35 to 9.38 μg/mL) in comparison to 5-Fluorouracil after treatment (IC₅₀: 5 μg/mL).     

Synthesis and evaluation of novel ascorbyl cinnamates as potential anti-oxidant and antimicrobial agents

Research on Chemical Intermediates - An efficient preparation procedure has been proposed for the synthesis of 5,6-di-O-cinnamyl-l-ascorbic acid ester (5,6-CA–AA) and 2-O-cinnamyl-l-ascorbic...     

Synthesis,characterization, and antimicrobial evaluation of some novel anthracene heterocycles derivatives

A series of novel heterocyclic compounds containing anthracene moiety was synthesized. Reaction of (11R,15S)-9,10-dihydro-9,10-[3,4]furanoanthracene-12,14-dione with 2-cyanoacetohydrazide gave 2-cyano-pyrroloanthracen acetamide (1) , which acts as an adaptable material for the synthesis of new heterocyclic compounds. The synthesized compounds were examined for their antimicrobial activity against Escherichia coli and Staphylococcus aureus via p-iodonitrotetrazolium violet formazon assay. The results exhibited great activity against the tested strains with a minimum bactericidal concentration range from 0.636 to 3.8 mg/mL) and 0.159 to 3.6 mg/mL for E coli and S aureus, respectively. Interestingly, the highest activity was recorded for chromene derivative (6) against both strains.     

Synthesis and structure of styryl-substituted azines

New photochromic derivatives of 2-styrylquinoline and 2-styrylquinoxaline were obtained by the condensation of the methyl derivatives of the mentioned heterocycles with substituted benzaldehydes in the presence of basic and acidic catalysts, and also under the conditions of Wittig reaction. The structure of compounds obtained was proved by physicochemical analysis methods including XRD.     

Synthesis and characterization of fluorinated polyimides derived from novel unsymmetrical diamines

Two kinds of aromatic, unsymmetrical diamines with ether-ketone group, 3-amino-4′-(4-amino-2-trifluoromethylphenoxy)-benzophenone and 4-amino-4′-(4-amino-2-trifluoromethylphenoxy)-benzophenone, were successfully synthesized with two different synthetic routes. Then, they were polymerized with 4,4′-oxydiphthalic anhydride, 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, and 2,2′-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride to form a series of fluorinated polyimides via a conventional two-step thermal or chemical imidization method. The resulting polyimides were characterized by measuring their solubility, viscosity, mechanical properties, IR-FT, and thermal analysis. The results showed that the polyimides had inherent viscosities of 0.48-0.68 dl/g and were easily dissolved in bipolarity solvents and common, low-boiling point solvents. Meanwhile, the resulting strong and flexible polyimide films exhibited excellent thermal stability, e.g., decomposition temperatures (at 10% weight loss) are above 575 °C and glass-transition temperatures in the range of 218-242 °C. The polymer films also showed outstanding mechanical properties, such as tensile strengths of 86.5-132.8 MPa, elongations at break of 8-14%, and initial moduli of 1.32-1.97 GPa. These outstanding combined features ensure that the polymers are desirable candidate materials for advanced applications.     

Synthesis of unsymmetrical arylthiophenes and bithienyls via oxidative cyclization of 1,3-butadiene-1-thiols

Oxidative cyclization of 2-mercapto-5-aryl-2,4-pentadienoic acids with iodine produced the respective 5-aryl-2-thenoic acids. The method was also suitable for the synthesis of unsymmetrical substituted 2,2′-bithienyls, and 2,3′-bithienyls. The synthesis of 5-carboxy-2′-bromo-5′-phenyl-2,3′-bithienyl from benzal-acetone demonstrated that oxidative cyclization of 1,3-butadiene-1-thiols is a useful procedure for preparing 5′-aryl-2,3′-bithienyls from simple carbonyl compounds. Preferential ring bromination of 2-phenyl-4-methyl-thiophene with N-bromosuccinimide and a radical catalyst was also observed.     

Synthesis and photochromism of novel unsymmetrical diarylethenes with an azaindole unit

A new class of unsymmetrical photochromic diarylethenes with an azaindole moiety has been firstly synthesized. Their properties, including photochromism, crystal structure, as well as fluorescence, were investigated systematically. The azaindole was connected directly to the central cyclopentene ring as a heteroaryl moiety and available to participate in the photoisomerization reaction. Each of the diarylethenes exhibited favorable photochromism, good thermal stability, remarkable fatigue resistance, and notable fluorescence switches in both solution and solid media. The substituents at the para-position of the terminal benzene ring affected evidently their properties: the electron-donating methoxy could be effective to enhance the cyclization quantum yield, while the electron-withdrawing cyano could shift the absorption maximum to a longer wavelength in both hexane and solid film. The results revealed that the introduction of azaindole moieties and different substituents played an important role in the photoisomerization process of these diarylethenes.     

Synthesis and characterization of novel antimicrobial cationic polyelectrolytes

Cationic polyelectrolytes containing quaternary nitrogen atoms within the main chain were prepared via condensation polymerization of epichlorhydrin (ECH) with benzyl amine (BA). Polyelectrolytes having different molecular weights were obtained by varying the ECH/BA mole ratio. Cationic polymers were characterized by ¹H-NMR and gel permeation chromatography. The antimicrobial activity of the polymers was tested against bacteria, yeast, and fungi.     

Synthesis and antimicrobial activity of novel chalcone derivatives

A series of novel 3-[N, N-bis(2-hydroxyethyl)-amino]-chalcone derivatives 3a–3j were synthesized by the aldol condensation of [N, N-bis(2-hydroethyl)-3-amino]-acetophenone 2 with aromatic aldehydes. Their structures were further confirmed by ESI-HRMS, ¹H NMR, IR and elemental analysis. X-ray analysis reveals crystal 3b is a monoclinic system with P2₁/n space group. The antimicrobial activities of the newly synthesized chalcones in vitro were evaluated and the results indicated that most compounds presented moderate to good antimicrobial activities, especially the antifungal capability. Compounds 3a, 3d, 3f and 3g revealed obvious potency against Candida albicans with MIC values of 32 μg/mL, which were better compared with others.