Farag A. El-Essawy

Anti-HIV Activity of New Substituted 1,3,4-Oxadiazole Derivatives and their Acyclic Nucleoside Analogues

A number of new 5-[(naphthalen-5-yloxy)methyl]-1,3,4-oxadiazole derivatives, 2 - 5 and 8 - 11, were synthesized. The 2-{5-[(naphthalen-5-yloxy)methyl]-1,3,4-oxadiazol-2-ylthio}acetohydrazones 6a and 6b were synthesized by the reaction of the hydrazide 4 with the corresponding monosaccharides. Cyclization of the sugar hydrazones 6a and 6b with acetic anhydride afforded the substituted oxadiazoline derivatives 7a and 7b. The synthesized compounds were evaluated for their antiviral activity against, the human immunodefi ciency virus (HIV-1) and some of these compounds showed moderate to high antiviral activity.

Synthesis of New Pyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidines and Their Use in the Preparation of Tetraheterocyclic Systems

8,10-Dimethyl-3-(unsubstituted, methyl, ethyl, n-butyl, phenyl)-4-hydroxypyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidin-2(1H)-ones and 3-(2-hydroxyethyl)-2,8,10-trimethylpyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidin-4-ol were synthesized by cyclocondensation of 3-amine-4,6-dimethyl-1H-pyrazolo[3,4-b]pyridine with ethyl malonates and α-acetyl-γ-butyrlolactone. Dichloro- and diazido- derivatives were obtained from the reaction of pyridopyrazlopyrimidine derivatives with POCl3 followed by NaN3. The tetrahetrocyclic systems were formed by cyclization of 4-chloro-3-(2-chloroethyl)-2,8,10-trimethylpyrido[2′,3′:3,4]pyrazolo[1,5-a]pyrimidine with the appropriate primary amines. The structures of all compounds were established by NMR and mass spectra.

Analysis of the essential oil from the aerial parts of Psoralea pubescence (Miq.) Standl and its antibacterial activity.

The essential oil from aerial parts of Psoralea pubescence (Miq.) Standl (Leguminoseae) was analyzed by gas chromatography (GC) and GC/mass spectroscopy systems. The major components identified were psoralen (24.8%), bakuchiol (21.3%), β-caryophyllene (8.5%), germacrene D (6.8%), and α-humulene (4.6%). The major volatiles released by β-glucosidase treatment of the aqueous plant residue were δ-pinene (28.3%), germacrene D (13.6%), and tricyclene (10.2%). The oil showed significant antibacterial activity against Staphylococcus aureus, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa, while the β-glucosidase-liberated fraction was inactive.

Anti-Hepatitis B Virus Activity of New 1,2,4-Triazol-2-yl- and 1,3,4-Oxadiazol-2-yl-2-pyridinone Derivatives

A number of 1,3,4-oxadiazole, 3 - 9, and 1,2,4-triazole derivatives, 13 - 15, were synthesized starting form the acid hydrazide 1. The 1,3,4-thiadiazole derivative 12 was prepared from the substituted phenylthiosemicarbazide derivative 11 by treatment with sulfuric acid. The aryl hydrazone derivatives 10a - c were synthesized by reaction of the hydrazide 1 with the corresponding ketones. The thioalkyl derivatives 16a - e were prepared by akylation of the thiol derivatives 3 and 13 with different alkylating agents. The newly synthesized compounds were tested for their anti-HBV activity and some of these compounds showed high antiviral activity

Construction of 1,3-disubstituted 4-oxo-1,4-dihydroquinolines as a potential antibacterial agents

A novel series of 1,3-disubstituted 4-oxo-1,4-dihydroquinolines as antimicrobial agents were designed and synthesized. Their structures have been confirmed using spectroscopic analyses (IR, NMR, and EI-MS). Most of the newly prepared compounds were screened for their antimicrobial activities against two Gram-positive bacterial strains and six Gram-negative bacterial strains. Many of the synthesized compounds displayed a high antimicrobial activity in comparison with reference drugs, for example compounds 4–6, 15, 17, and 18.

Synthesis of some new quinazolin-4(3H)-one derivatives and evaluation of their anticonvulsant activity

We reported the synthesis of a novel series of quinazolin-4(3H)-one derivatives bearing oxadiazole, thiadiazole, and other moieties in the 3-position of the quinazolinone nucleus using appropriate synthetic route. The compounds were evaluated for their anticonvulsant activity using picrotoxin model, GABA-A receptor antagonist. Five compounds showed significantly prolonged times for convulsions compared with the standard drug phenobarbital.Graphical abstract

Formation of novel pyrido[3‘,2‘:4,5]thieno [2,3-e][1,2,4]triazolo[4,3-c]pyrimidines and their acyclic C-nucleosides analogues: synthesis of 3-(Alditol-1-yl)pyridothienotriazolopyrimidines

A series of the hydrazones were prepared by the reaction of 4-hydrazino-7,9-dimethylpyrido[3′,2′:4,5]thieno [2,3-d]pyrimidine (1) with monosaccharides, and their acetylation was studied. The oxidative cyclisation of the hydrazones 3a–c gave 3-(Alditol-1-yl)-pyridothienotriazolopyrimidenes 5a–c, whose acetylation was carried out. Also, oxidative cyclisation of arylidenes 7a,b gave the pyridothienotriazolopyrimidines 8a,b.

Synthesis of novel 3-substituted pyridothienopyrimidine derivatives with biological evaluation as antimicrobial agents

Novel 3-substituted pyridothienopyrimidine derivatives have been synthesized via the reaction of 2-{7,9-dimethyl-4-oxopyrido[3′,2′:4,5]thieno[3,2-d]pyrimidin-3(4H)-yl}acetohydrazide(5) with a variety of active reagents and chemicals. Structures of the newly synthesized compounds were established based on spectral data. The resulting pyridothienopyrimidine derivatives were evaluated for their possible antimicrobial activity and some of them represent a new class of potentially antimicrobial compounds, especially compounds 9 and 18 which displayed the highest activity against Gram-positive bacteria, Gram-negative bacteria, and Fungi in MIC range of 0.12―1.95 μg/mL.

Synthesis of New Isolated and Fused Tri- and Tetracyclic Pyridine Derivatives

A number of functionalized pyridine derivatives in which the pyridine ring is linked to triazole, thiadiazole, thiazole, and tetrazole moieties were synthesized by cyclization with carbon disulfide, phenylisothiocyanate, and sodium azide. Benzylation of the synthesized tetrazolylmethylpyridone derivative afforded the N(1)-benzylated product; its crystal structure is reported. The substituted fused tetracyclic pyridofuropyrimidine was synthesized by sequential reactions starting from the 2-pyridone derivative.

Synthesis of Functionalized Pyrano[3,2‐c]pyridines and Their Transformations to 4‐Hydroxy‐3[(1E)‐N‐hydroxyalkanimidoyl]pyridones

Abstract Reaction of 4‐hydroxy‐6‐methyl‐2(1H)‐pyridones 1a and 4‐hydroxy‐1,6‐dimethyl‐2(1H)‐pyridones 1b with diethyl malonates 2a–e leads to the formation of pyrano[3,2‐c]pyridines 4a–j. Degradation of 4a–i affords the corresponding ketones 6a–i. Condensation of ketones 6a–i with hydroxyl amine or phenyl hydrazine hydrochloride is described.