Determination and evaluation of acidity constants of some imidazole and thiazole linked acetamide compounds

In this work, the effect of substituents on the acidity constants of some acetamide derivatives was investigated. The acidity constants of nine acetamide derivatives were determined at 25 °C using a UV spectrophotometric method. When the molecules possessed different substituents the values of the acidity constants changed from 6.01 to 8.22 for the first protonation and from 3.07 to 4.73 for the second protonation. The first protonation under these circumstances was observed to occur on the nitrogen atom of the 2-mercaptoimidazole ring. The second protonation was observed to occur on the nitrogen atom of the thiazole ring

Synthesis, antimicrobial and antioxidant activities of pyridyl substituted thiazolyl triazole derivatives

In this present study, 63 different 5-[4-methyl-2-(pyridin-3/4-yl)thiazole-5-yl]-4-substituted-3-substituted benzylthio-4H-1,2,4-triazole derivatives were synthesized, and evaluated for their in vitro antimicrobial activity against various human pathogenic microorganisms and antioxidant activity. The derivatives were synthesized in a multi-step synthesis procedure including triazole and thiazole ring closure reactions, respectively. The synthesized derivatives (A1-24; B1-39) were screened for their antibacterial, antifungal, and antioxidant activities compared to standard agents. The derivatives possessing 3-pyridyl moiety particularly exhibited relatively high antibacterial activity (MIC= < 3.09-500 µg/mL) against Gram-positive bacteria, and compounds possessing 4-pyridyl moiety showed remarkable antioxidant activity.Eskisehir Osmangazi Universit

Synthesis and antitumor activity evaluation of new 2-(4-aminophenyl)benzothiazole derivatives bearing different heterocyclic rings

WOS: 000359815200017PubMed ID: 25198890Twenty-five new N-[4-(benzothiazole-2-yl)phenyl]acetamide derivatives bearing different heterocyclic ring systems were synthesized using 2-(4-aminophenyl)benzothiazole structure as a pharmacophoric group. Final compounds were screened for their potential antitumor activity in vitro against approximately 60 human tumor cell lines derived from nine neoplastic diseases at National Cancer Institute, USA. 2-(4-Aminophenyl)benzothiazole structure was prepared by the reaction of 4-aminobenzoic acid and 2-aminothiophenol in polyphosphoric acid using microwave irradiation. After acetylation reaction, amide compounds 2a and 2b were obtained, which were then reacted with 2-mercapto(benz)imidazole/benzothiazole/benzoxazole derivatives in acetone with the presence of potassium carbonate to gain final compounds (3-27). Among all tested compounds, compound 10, namely N-[4-(benzothiazole-2-yl)-3-chlorophenyl]-2-[(benzimidazole-2-yl)thio]acetamide, and compound 16, namely N-[4(benzothiazole-2-yl)phenyl]-2-[(1,5-diphenyl-1H-imidazole-2-yl)thio]acetamide, were found to be of considerable anticancer activity against some cancer cell lines.Commission of Scientific Research Projects of Eskisehir Osmangazi University [ESOGU/200819010]; Eskisehir Osmangazi UniversityThis work was supported by the Commission of Scientific Research Projects of Eskisehir Osmangazi University (ESOGU/200819010). The authors gratefully acknowledge the financial support by Eskisehir Osmangazi University

A quantum chemical DFT/HF study on acidity constants of some benzothiazole and thiazole derivatives

WOS: 000330160400004The acid dissociation (K-a) constants of some 4-and/or 6-substituted-2-aminobenzothiazole compounds have been investigated theoretically. The gas and aqueous phase geometries, thermal and solvation free energies have been calculated with full geometry optimization by using HF (6-31G(d)) and B3LYP (6-31G(d)) methods for 2-aminobenzothiazole, 2-aminothiazole derivatives and their fixed models. From the calculated acidity constants of investigated compounds, it has been detected that the protonation occurs at the the nitrogen atom of the amino group for 2-aminobenzothiazoles and at ring nitrogen atom for 2-aminothiazoles. Acceptable correlations have been observed between theoretically (HF and B3LYP) and experimental pK(a) values of the molecules with regression coefficients (R-2 = 0.98, 0.86) and (R-2 = 0.98, 0.85) for the protonation of benzothiazole and thiazole molecules, respectively. Theoretical calculations also show that basicity of the studied compounds increase in the presence of electron donor substituents

Synthesis of some N-[4-(benzothiazole-2yl)phenyl]-2-aryloxyacetamide derivatives and their anticancer activities

WOS: 000306524200007PubMed ID: 21823837In this study, some N-[4-(Benzothiazole-2-yl)phenyl]-2-aryloxyacetamide derivatives were prepared by reacting N-[4-(benzothiazole-2yl)phenyl]-2-chloroacetamide and different substituent phenol or thiophenol derivatives. The anticancer activities of the compounds obtained were investigated. It was observed that some of the compounds, namely 25 and 38, showed notable anticancer activity.Eskisehir Osmangazi University [ESOGU/200819010]This work was supported by the Commission of Scientific Research Projects of Eskisehir Osmangazi University (ESOGU/200819010). The authors gratefully acknowledge the financial support by Eskisehir Osmangazi University. Authors also would like to thank to National Cancer Institue (NCI), Bethesda, MD, USA for in vitro screening of our compounds in human cancer cell lines.Eskisehir Osmangazi Universit

BAZI 4-AMİNOKİNAZOLİN TÜREVLERİNİN BAZLIK DAVRANIŞLARI ÜZERİNE TEORİK BİR ÇALIŞMA

The acidity constants (Ka) of some 6-substitue-4-aminoquinazoline compounds were investigated theoretically. The gas and aqueous phase geometries and the possible tautomeric forms were defined with full geometry optimization by using B3LYP/6-31G(d) method for 6-substitue-4-aminoquinazoline derivatives. It was found that most stable forms are amino form and the first protonation occurs at ring nitrogen atom(N1)

A quantum chemical DFT/HF study on acidity constants of some benzothiazole and thiazole derivatives

102-110The acid dissociation (Ka) constants of some 4-and/or 6-substituted-2-aminobenzothiazole compounds have been investigated theoretically. The gas and aqueous phase geometries, thermal and solvation free energies have been calculated with full geometry optimization by using HF (6-31G(d)) and B3LYP (6-31G(d)) methods for 2-aminobenzothiazole, 2-aminothiazole derivatives and their fixed models. From the calculated acidity constants of investigated compounds, it has been detected that the protonation occurs at the the nitrogen atom of the amino group for 2-aminobenzothiazoles and at ring nitrogen atom for 2-aminothiazoles. Acceptable correlations have been observed between theoretically (HF and B3LYP) and experimental <span style="mso-bidi-font-family: " times="" new="" roman";mso-fareast-language:tr"="" lang="EN-GB">pKa values of the molecules with regression coefficients (R2 = 0.98, 0.86) and (R2= 0.98, 0.85) for the protonation of benzothiazole and thiazole molecules, respectively. Theoretical calculations also show that basicity of the studied compounds increase in the presence of electron donor substituents. </span

Synthesis, structure elucidation and determination of acid dissociation constant, tautomerism of pyrido [1,2-a] benzimidazole-2,4-dione

The first starting material, 1H-2-acetylbenzimidazole, 4, was synthesized by o-phenylenediamine, 1, and lactic acid solution, 2, in hydrochloric acid medium on the first step than, oxidation reaction was performed by CrO3 in acetic acid medium on the second step. The last starting material, ethyl 2-(2-acetylbenzimidazol-1-yl) acetate, 6, was synthesized by using first starting material, 4, ethyl 2-bromoacetate, 5, and K2 CO3 in acetone medium. The target compound, pyrido[1,2-a] benzimidazole-2,4-dione, 7, was synthesized by using the last starting material, 5, in sodium ethoxide medium. The compound, 7, can be found in two forms which are keto and enol which would be evaluated in this study. For the evaluation, it was performed some spectroscopic studies. In addition, it was evaluated experimentally obtained acidity constant, pKa value and tautomeric equilibrium of the compound, 7, by using ultraviolet-visible (UV-Vis) spectrophotometer. All of these studies have shown that the valid form of the compound, 7, is keto form

DETERMINATION AND EVALUATION OF ACIDITY CONSTANTS OF SOME IMIDAZOLE AND THIAZOLE LINKED ACETAMIDE COMPOUNDS

In this work, the effect of substituents on the acidity constants of some acetamide derivatives was investigated. The acidity constants of nine acetamide derivatives were determined at 25 °C using a UV spectrophotometric method. When the molecules possessed different substituents the values of the acidity constants changed from 6.01 to 8.22 for the first protonation and from 3.07 to 4.73 for the second protonation. The first protonation under these circumstances was observed to occur on the nitrogen atom of the 2-mercaptoimidazole ring. The second protonation was observed to occur on the nitrogen atom of the thiazole ring