Arif Mermer

Synthesis and antimicrobial activity of new piperazine-based heterocyclic compounds

Abstract The hydrazide 5, that was obtained from 1-(4-fluorophenyl)piperazine (1), was converted to the corresponding carbothioamides 6a–c by the reaction with alkyl(aryl) isothiocyanates. The synthesis of conazole analogs 10a–f was performed via the intermediary of triazoles 7a–c. The condensation of triazoles 7a–c with several heterocyclic amines in the presence of formaldehyde afforded the corresponding N-aminoalkylated triazoles 11–14. The effect of different catalysts and solvents on conventional and microwave (MW)-prompted reactions was examined. The synthesized compounds were screened for their antimicrobial activities.

Microwave-assisted and conventional synthesis of novel antimicrobial 1,2,4-triazole derivatives containing nalidixic acid skeleton

Abstract Carbothioamides 4a,b, obtained from nalidixic acid, were converted to the corresponding 1,3-thiazolidine derivatives 5a,b by cyclocondensation with 2-bromo-1-(4-chlorophenyl)ethanone. Treatment of 4a,b with base afforded 1,2,4-triazoles 6a,b. The synthesis of 1,3-oxazolidine 7 was performed by the reaction of compound 4a with ethyl bromoacetate. Treatment of 4a with acid produced 1,3,4-thiadiazole 8. The reaction of compounds 6a and 6b with several heterocyclic amines in the presence of formaldehyde gave the corresponding Mannich bases 9–15 containing various pharmacophore groups. Conventional and microwave-assisted methods were used for the synthesis. The effect of an acid catalyst on Mannich reactions was investigated. The structures of the newly synthesized compounds were elucidated on the basis of 1H NMR, 13C NMR, FTIR, EIMS techniques, and elemental analysis. All compounds were screened for their antimicrobial activity.

The electrochemical and spectroelectrochemical properties of metal free and metallophthalocyanines containing triazole/piperazine units

The synthesis and characterization of novel peripherally tetra [1,2,4]-triazole substituted metal-free phthalocyanine and its metal complexes (Zn(II), Ni(II), Pb(II), Cu(II) and Fe(II)) and the investigation of electrochemical and spectroelectrochemical properties of metal-free, Zn(II), Pb(II), Fe(II) phthalocyanines were performed for the first time in this study. Electrochemical characterizations of the complexes were performed with voltammetric and in situ spectroelectrochemical measurements. Voltammetric responses of the complexes supported the proposed structures, since complexes bearing redox inactive Pc ring metal centers just gave Pc based electron transfer reactions, while iron phthalocyanine went to metal based electron transfer reaction in addition to the Pc based ones. Electron withdrawing nature of [1,2,4]-triazole substituents shifted the redox processes toward the positive potentials. All complexes were electropolymerized during the oxidation reactions in dichloromethane (DCM) solvent. Types of the metal center of the complexes altered the electropolymerization reactions of the complexes. Spectra and colors of the electrogenerated redox species of the complexes were also determined with in situ spectroelectrochemical and in situ electrocolorimetric measurements.

Conventional and microwave prompted synthesis, antioxidant, anticholinesterase activity screening and molecular docking studies of new quinolone-triazole hybrids

The synthesis of ethyl 4-oxo-1,4-dihydroquinoline-3-carboxylates (4, 5) was performed via the reaction of corresponding anilines with diethyl ethoxymethylenemalonate under conventional and also microwave promoted conditions. The treatment of 4 and 5 afforded the corresponding hydrazides (6 and 7). These hydrazides were converted to the corresponding carbo(thio)amides (9a-f and 10a-e) which were then subjected to an intramolecular cyclisation leading to the formation of quinolone-triazole hybrids (11a-f and 12a-e). The newly synthesized compounds were screened for their biological activities such as antioxidant capacity (AC) and acetylcholinesterase Activity. Inhibition of cholinesterases is an effective method to curb Alzheimers disease, a progressive and fatal neurological disorder. A series of some novel quinolonederivatives were designed, synthesized, and their inhibitory effects on AChE were evaluated. We obtained our compounds and determined their anticholinesterase activities according to the Ellmans method. 9b and 10c showed the best AChE inhibition with 0.48 ± 0.02 and 0.52 ± 0.07, respectively. Docking studies were performed for the most active compounds (9b, 10c) and interaction modes with enzyme active sites were determined. As a result of these studies, a strong interaction between these compounds and the active sites of AChE enzyme was revealed.

Synthesis, biological activity and structure activity relationship studies of novel conazole analogues via conventional, microwave and ultrasound mediated techniques

1,2,4-Triazole derivatives containing a piperazine nucleus (4a-d and 10) were prepared starting from 1-(2-methoxyphenyl)piperazine or ethyl 4-(4-amino-2-fluorophenyl)piperazine-1-carboxylate via several steps. The synthesis of fifteen compounds (7a-l and 13a-c), which can be considered as new analogues of azole class antifungals was performed starting from 1,2,4-triazoles (4a-d and 10) via three steps containing the condensation with 2-bromo-1-(4-chlorophenyl)ethanone, reduction of carbonyl group to alcohol and alkylation of OH group, respectively. All the reactions were examined under conventional, ultrasound and microwave irradiation conditions as green chemistry techniques, and optimum conditions were defined. The newly synthesized compounds were screened for their biological potentials including antimicrobial, antioxidant, antiurease and anti α-glucosidase activities and promising results were obtained. The enzyme inhibitory potentials of these compounds were further validated through molecular docking.