Mohamed R. Shaaban

Synthesis and analgesic/anti-inflammatory evaluation of fused heterocyclic ring systems incorporating phenylsulfonyl moiety

A series of pyrazolo[1,5-a]pyrimidine, triazolo[1,5-a]pyrimidine, and pyrimido[1,2-a]benzimidazole ring systems incorporating phenylsulfonyl moiety were synthesized via the reaction of 3-(N,N-dimethylamino)-1-aryl-2-(phenylsulfonyl)prop-2-en-1-one derivatives 2a,b with appropriate nitrogen nucleophiles. The analgesic and anti-inflammatory activities of the newly synthesized compound were investigated in vivo. 3-Bromo-2-phenyl-6-(phenylsulfonyl)-7-(4-methylphenyl)pyrazolo[1,5-a]pyrimidine (5e) was found to have an excellent analgesic activity in comparison with indomethacin as a reference drug, while the highest anti-inflammatory effect was observed in the case of 2-(4-bromophenyl)-6-(phenylsulfonyl)-5-(4-methylphenyl)pyrazolo[1,5-a]pyrimidine (5d). From the structure-activity relationship (SAR) point of view, the analgesic/anti-inflammatory activity of pyrazolo[1,5-a]pyrimidine derivatives was found to be much higher than triazolo[1,5-a]pyrimidine and pyrimido[1,2-a]benzimidazole derivatives.

Single Step Synthesis of New Fused Pyrimidine Derivatives and Their Evaluation as Potent Aurora-A Kinase Inhibitors

A simple, facile, efficient and one pot three-component procedure for the synthesis of pyrazolo[1,5-a]pyrimidines, triazolo[1,5-a]pyrimidines and pyrimido[1,2-a]benzimidazoles ring systems incorporating phenylsulfonyl moiety was developed via the reaction of 1-aryl-2-(phenylsulfonyl)ethanone derivatives 1a-d with the appropriate heterocyclic amine and triethyl orthoformate and evaluated as Aurora-A kinase inhibitors. The cytotoxic activity of the newly synthesized compounds against HST116 colon tumor cell line was investigated. 2,7-Diphenyl-6-(phenylsulfonyl)pyrazolo[1,5-a]pyrimidine (4b) and its p-methoxy analogue 4c were found to be equipotent to Doxorubicin as a reference drug. Molecular modeling study was carried out in order to rationalize the in vitro anti-tumor results.

Recent advances in the therapeutic applications of pyrazolines.

Introduction: Pyrazolines are well-known and important nitrogen-containing five-membered ring heterocyclic compounds. Various methods have been worked out for their synthesis. Several pyrazoline derivatives have been found to possess diverse biological properties, which has stimulated research activity in this field. Areas covered: The present review sheds light on the recent therapeutic patent literature (2000 – 2011) describing the applications of pyrazolines and their derivatives on selected activities. Many of the therapeutic applications of pyrazoline derivatives have been discussed, either in the patent or in the general literature areas in this review. In addition to selected biological data, a wide range of pharmaceutical applications and pharmaceutical compositions are also summarized. Expert opinion: Pyrazoline derivatives have numerous prominent pharmacological effects, such as antimicrobial (antibacterial, antifungal, antiamoebic, antimycobacterial), anti-inflammatory, analgesic, antidepressant and anticancer. Further pharmacological effects include cannabinoid CB1 receptor antagonists, antiepileptic, antitrypanosomal, antiviral activity, MAO-inhibitory, antinociceptive activity, insecticidal, hypotensive, nitric oxide synthase inhibitor, antioxidant, steroidal and antidiabetic. Lastly, they also effect ACAT inhibition, urotensin II and somatostatin-5 receptors, TGF-β signal transduction inhibitors and neurocytotoxicity inhibitors activities. Many new pyrazoline derivatives have been synthesized and patented, but there are still new aspects to explore and work on.

Synthesis and antimicrobial evaluation of new thiophene and 1,3,4-thiadiazole derivatives

A Facile route to some new thiophene derivatives via the reaction of 3-mercapto-2-(1-methylbenzimidazole-2-carbonyl)-3-phenylaminopropenal (3) with 1-aryl-2-bromoethanones, chloroacetonitrile and ethyl bromoacetate is reported. Reaction of 3 with hydrazonoyl halides afforded 1,3,4-thiadiazole derivatives incorporating a benzimidazole moiety. Antimicrobial and antifungal activities of selected examples of the new products were evaluated.

Synthesis and antimicrobial evaluation of novel pyrazolo〔1,5-a〕pyrimidine triazolo〔1,5-a〕pyrimidine and Pyrimido〔1,2-a〕benzimidazole derivatives

The applicability and synthetic potency of E-1 -(1-methylbenzimidazol-2-yl)-3 -N,N-dimethylaminoprop-2-enone towards some nitrogen nucleophiles was investigated as a convenient route for the synthesis of some novel aminopyrimidine, pyrazolo[1 ,5-a]pyrimidine, triazolo[1 ,5-a]pyrimidine, pyrimido[1,2-a]benzimidazole, and pyrido[2,3-d]pyrimidine derivatives. Some of the newly synthesized compounds were tested in vitro for their antibacterial and antifungal activities, and showed promising results.

AN EFFICIENT SINGLE STEP SYNTHESIS OF PYRIDAZINE, PYRAZOLO[5,1-c]-1,2,4-TRIAZINE, 1,2,4-TRIAZOLO[5,1-c]-1,2,4-TRIAZINE AND 1,2,4-TRIAZINO[4,3-a]BENZIMIDAZOLE DERIVATIVES

Coupling of E-1-(l-methylbenzimidazol-2-yl)-3-(N,N-dimethylamino)prop-2-enone (1) with the arenediazonium salt gave hydrazonopropanal 5 which underwent cyclocondensation with active methylene compounds to afford substituted pyridazin-6-imine 8 and 11. The enaminone 1 coupled also with the diazonium salts prepared from aminopyrazole, aminotriazole and 2-amino-1H-benzimidazole to afford pyrazolo[5,l-c]-l,2,4-triazine 15, 1,2,4-triazolo[5,1-c]-1,2,4-triazine 19, 1,2,4-triazino[4,3-a]benzimidazole 23 derivatives, respectively.

SYNTHESIS AND ANTIMICROBIAL EVALUATION OF NOVEL PYRAZOLO[1,5-a]PYRIMIDINE, PYRIMIDO[1,2-a]BENZIMIDAZOLE, TRIAZOLO[4,3-a]PYRIMIDINE AND PYRIDO[1,2-a]BENZIMIDAZOLE DERIVATIVES INCORPORATED PHENYLSULFONYL MOIETY

Phenylsulfonylacetonitrile (1) reacts with dimethylformamide dimethyl acetal (DMF-DMA) to afford 3-(dimethylamino)-2-(phenylsulfonyl)acrylonitrile (2). Enaminonitrile 2 reacts with 5-aminopyrazole derivatives 3a-e, 5-amino-l,2,4-triazole (7) and 2-aminobenzimidazole (11) to afford new pyrazolo[1,5-a]pyrimidine, triazolo[4,3-a]pyrimidine and pyrimido[1,2-a]benzimidazole derivatives 4a-e, 9 and 12, respectively. Also, 3-(dimethylamino)-2-(phenylsulfonyl)acrylonitrile (2) reacts with 2-(1H-benzimidazol-2-yl)acetonitrile (13) to give the corresponding pyrido[1,2-a]benzimidazole derivative 15. Some of the newly synthesized compounds were tested in vitro for their antibacterial and antifungal activities, and showed promising results.

Synthesis of heterocycles and fused heterocycles catalyzed by nanomaterials

This review focuses, on the application of nanomaterials as heterogeneous catalysts for the synthesis of different heterocyclic systems. We pay special attention to the specific synthesis of such systems in an organized manner with respect to the type of the heterocyclic systems.

Kinetic and mechanistic investigations on the oxidation of N’-heteroaryl unsymmetrical formamidines by permanganate in aqueous alkaline medium

Kinetic studies on the oxidation of two substituted azinyl formamidines (Azn-Fs), namely N,N-dimethyl-N’-(pyrimidin-2-yl) formamidine (Pym-F) and N,N-dimethyl-N’-(pyridin-2-yl) formamidine (Py-F), by alkaline permanganate have been performed by spectrophotometry. The spectroscopic and kinetic evidence reveals the formation of 1:1 intermediate complexes between the oxidant and substrates. The influence of pH on the oxidation rates indicated that the reactions are base-catalyzed. The reactions show identical kinetics, being first order each in [MnO4−]0 and [Azn-F]0, but with a fractional first-order dependence on [OH−]. The effect of temperature on the reaction rate has been studied. Increasing ionic strength has no significant effect on the rate. The final oxidation products of Pym-F and Py-F were identified as 2-aminopyrimidine and 2-aminopyridine, respectively, in addition to dimethyl amine and carbon dioxide. Under comparable experimental conditions, the oxidation rate of Py-F is higher than that of Pym-F. A reaction mechanism adequately describing the observed kinetic behavior is proposed, and the reaction constants involved in the different steps of the mechanism have been evaluated. The activation parameters with respect to the rate-limiting step of the reactions, along with thermodynamic quantities, are presented and discussed.

A convenient synthesis of pyrazole-substituted heterocycles

(E)-1-(5-Methyl-1-phenylpyrazol-4-yl)-3-(N,N-dimethylamino)-2-propen-1-one reacts with hydrazine, hydroxylamine, guanidine and aminopyrazole derivatives to afford the corresponding 3,4′-bipyrazole, pyrazolylisoxazole, pyrazolylpyrimidine and pyrazolo[1,5-a]pyrimidine derivatives, respectively. It reacts also with benzoquinone, naphthoquinone and N-benzoylglycine to give the corresponding benzofuran and pyrazolylpyranone derivatives, respectively.