Synthesis of Some Novel Thiadiazoles and Thiazoles Linked to Pyrazole Ring

New Antibacterial 1,3,4-Thiadiazole Derivatives With Pyridine Moiety

1,3,4-Thiadiazole compounds were synthesized using pyridine carboxylic acid derivatives and thiosemicarbazide derivatives. The molecular structures of the resulting compounds were characterized by spectroscopic methods such as ATR-FTIR, 1H-NMR, and elemental analysis. Its compounds were also examined for their antibacterial properties against some strains of bacteria. Five synthesized compounds showed varying antibacterial effects on Escherichia coli, Salmonella kentucky, Bacillus substilis and Klebsiella pneumoniae. This result revealed that some of the resulting compounds could be antibacterial agents.

The Chemistry of Acetylpyrazoles and Its Utility in Heterocyclic Synthesis

A literature survey revealed that a great deal of interest has been focused on the synthesis of functionalized pyrazole derivatives due to their synthetic and biological potentialities. The pharmacological activities that have been found for some pyrazole derivatives include selective enzyme inhibition, antiviral, estrogen receptor agonist, anti‐inflammatory, anticancer, antiobesity, and antitumor properties. Other activities such as potential inhibitors of HIV‐1, pesticides, fungicides, and antihypertensive agents were reported for other pyrazole derivatives. This review summarizes the synthetic methods and reactions of 3‐acetyl‐pyrazoles, 4‐acetyl‐pyrazoles, and 3,4‐di‐acetyl‐pyrazoles. Most reaction types have been successfully applied and used in the production of biologically active compounds. The aim of this review is to focus mainly on the utility of acetylpyrazole derivatives in the synthesis of heterocyclic compounds during the period 1990–2018.

Synthesis and Antimicrobial Activity of Novel Azolopyrimidines and Pyrido‐Triazolo‐Pyrimidinones Incorporating Pyrazole Moiety

A new series of azolopyrimidine derivatives incorporating pyrazole moiety were synthesized by reaction of 1‐(pyrazol‐3‐yl)‐2‐propenone with a number of heterocyclic amines in the presence of a catalytic amount of acetic acid. The mechanism of formation of the products was also discussed, and the structure assigned was elucidated based on both elemental and spectral analyses data. In addition, 7‐(pyrazolyl)‐2‐thioxo‐5‐phenyl‐1,3‐dihydropyrido[2,3‐d]pyrimidin‐4‐one was used as starting material for preparation of a new series of pyridotriazolopyrimidines via its reaction with a variety of hydrazonoyl chlorides in dioxane using triethylamines as catalyst. The assigned structure for these products was also proved via elemental analysis and spectroscopic techniques (IR, 1H NMR, and Mass). Moreover, the antimicrobial activity of some selected examples of the new products was evaluated, and the results obtained revealed high activity of compound 20a against the Gram positive bacteria Staphylococcus aureus and the Gram negative bacteria Klebsiella pneumonie. All the tested compounds have no antifungal activity.