Mohamed A. El-Borai

Synthesis of pyrazolo[3,4-b]pyridines under microwave irradiation in multi-component reactions and their antitumor and antimicrobial activities - Part 1.

An efficient one-pot synthesis in multi-component system (MRCs) for the preparation of pyrazolo[3,4-b]pyridine derivatives from the reaction of 5-amino-1-phenyl-3-(pyridin-3-yl)-1H-pyrazole with 4-anisaldehyde and p-substituted β-ketonitriles or with pyruvic acid and some aromatic aldehydes in acetic acid medium. The reactions were carried out by two different techniques, conventional heating and microwave irradiation. These compounds were screened for their antibacterial activity against Gram-positive bacteria (Bacillus), Gram-negative bacteria (Escherichia coli, Enterobacter cloaca and serratia) and antifungal activity against Fusarium Oxysporum and Penicillium expansum. Also, among the synthesized compounds 4a-f tested for antitumor activity against liver cell line. Compounds 6-(4-Fluorophenyl)-4-(4-methoxyphenyl)-1-phenyl-3-(pyridin-3-yl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitrile (4e) and 4-(4-Methoxyphenyl)-1-phenyl-3,6-di(pyridin-3-yl)-1H-pyrazolo[3,4-b] pyridine-5-carbonitrile (4a) showed the highest activity.

Microwave-assisted synthesis of some new pyrazolopyridines and their antioxidant, antitumor and antimicrobial activities.

The chemical behavior of 4-(dimethylaminomethylene)-1-phenyl-3-(pyridin-3-yl)-1H-pyrazol-5(4H)-one (enaminone) (2) toward some active methylene reagents has been reported to give pyrazolopyridine derivatives. All the reactions were carried out by conventional heating and microwave irradiation technique. The antioxidant activity of the prepared compounds was studied using 1,1-phenyl-2-picrylhydrazyl (DPPH) assay. Compounds (4c) and (4d) showed the highest activity. The antitumor activity against liver and breast cell lines was tested. Compounds (6), (9) and (11) showed the highest activity for liver cell line while compounds (6) and (9) showed the highest activity for breast cell line. Compounds (4a-d) were screened for their antibacterial activity against Gram-positive, Gram-negative bacteria and antifungal activity.

New catalytic systems based on intercalated polymer-montmorillonite supports

A composite material was prepared by ion exchange between the ammonium salt of the α,ω-diamine-terminated oligo(butadiene-co-acrylonitrile) (ATBN) and the interlamellar cation of the montmorillonite (Na-MMT). Grafted free radical polymerization of both oligo(oxyethylene)methacrylate and chloromethylstyrene supported onto the above composite was prepared. The chloromethyl groups were modified to produce onium salts which are suitable as phase transfer catalysts. The catalytic activities were investigated in nucleophilic reactions of thiocyanate, cyanate and nitrite with alkyl or aryl halides. The effects of the nature and structure of the support, amount of catalyst, solvent, and the temperature on the rate of reactions were studied.

Preparation and application of functional polymers. Preparation of carbodiimides, ketenimines and imidoyl bromides using a poly(styryl diphenylphosphine dibromide)

acid, thereby depleting the effective polymerization concentration of this monomer. The feed ratio of the copolymerization affects the incorporation of SO2 into the copolymer very slightly. For a feed ratio variation factor of 5, the copolymer composition increased by a factor of 1.4 with respect to SO2 (Table 4). We suggest that the copolymerization reaction between acrylic acid and sulphur dioxide is somewhat different from the vinylic copolymerization reaction. To test whether any adverse side reactions may be complicating the copolymerization, the components in a solution polymerization were mixed in various sequences. The results indicate that sequence has no influence essentially on SO 2 incorporation. A more detailed investigation must be carried out to obtain a better understanding of this system. Studies are continuing.

Synthesis and spectral characterization of novel azomethine disperse dyes derived from pyrazolone moiety and their dyeing performance on polyester fabrics

A series of new azomethine dyes based on pyrazolone system have been synthesized via different routes. The solvatochromism for the dyes was evaluated with respect to spectroscopic properties in various solvents. The dyes were applied as disperse dyes on polyester fabrics and gave shade poor to excellent light fastness, washing, perspiration, sublimation, and rubbing fastness properties. Also the position of color in CIELAB coordinates (L*, a*, b*) and K/S value were investigated.

Dyeing, color fastness and antimicrobial properties of some mono and disazo disperse dyes derived from thiazole moiety

Three series of mono and disazo disperse dyes were synthesized from 2-amino-4-(pyridin-3-yl) thiazole. The structure of the synthesized dyes was confirmed by elemental analysis, ultraviolet-visible, infrared, proton and carbon nuclear magnetic resonance and mass spectroscopy. The dyeing parameters, perspiration, wash and light fastness of eighteen azo disperse dyes on polyester have been investigated. Application of these dyes on polyester fabric gave yellow to reddish hues for mono azo derivatives and reddish to dark brown hues for disazo derivatives with fair to moderate light fastness and moderate to good wash and perspiration fastness grade. In addition, the synthesized dyes were screened for their antimicrobial activities against some gram positive, gram negative bacteria and fungi. Some of the prepared dyes gave excellent results against most of the tested organisms.

Vicinal benzo[b]thiophene-5,6-dicarboxaldehyde in heterocyclic synthesis: a reagent for fluorescence determination of amino acids

Benzo[b]thiophene-5,6-dicarboxaldehyde reacts with dibenzyl ketone, thiodiacetic acid dimethyl ester, hydrazine, p-toluidine, p-aminoacetophenone and nitromethane to give the corresponding seven, six and five-membered rings condensed to benzo[b]thiophene. Reaction of benzo[b]thiophene-5,6-dicarboxaldehyde with p-toluidine in the presence of 2-mercaptoethanol gives highly fluorescent compounds. Also, benzo[b]thiophene-5,6-dicarboxaldehyde was applied to fluorogenic reaction with some amino acids and the obtained data were compared with the reported data in the case of o-phthaldehyde. The synthesised compounds were characterised by their elemental analysis, IR, 1H NMR and mass spectrometry

REACTION OF THIOPHENE DICARBOXALDEHYDES WITH p-AMINOACETOPHENONE: A NEW SYNTHESIS OF THIENOPYRROLE DERIVATIVES

Abstract The thiophene 3,4- and 2,3-dicarboxaldehydes react with p-aminoacetophenone in xylene to give N-(4-acetyl phenyl)-5,6-dihydro-4-oxo-4H-thieno[3,4-c] and [2,3-c]pyrroles. On the reaction of thiophene 2,3-dicarboxaldehyde in the presence of 2-mercaptoethanol, N-(4-acetyl phenyl)-2-thioalkyl-thieno[2,3-c]pyrrole and N-(4-acetyl phenyl)-2,5-dithioalkylthieno-[2,3-c]pyrrole are obtained, and characterized by 1H nmr and mass spectroscopy.