Abstract
The key intermediates in the present study to synthesize the title bridge-head nitrogen heterocycle compounds were N-substituted semicarbazides 2(a-c), which prepared by hydrazinolysis of the ethyl substituted carbamates 1(a-c) with hydrazine hydrate. These carbamates were prepared by the reaction of proper amines and ethylchloroformate. The reaction of these semicarbazides with ethanolic solution of carbon disulfide under strong basic conditions at room temperature, followed by acidification resulted in the formation of the corresponding potassium (2-arylcarbamoyl)hydrazine carbodithioate 3(a-c), while refluxing the ethanolic solution for three hours afforded 5-(arylamino)-1,3,4-oxadiazole-2- thioles 4(a-c). The potassium salts 3(a-c) were cyclized with hydrazine hydrate to 4-amino-5-arylamino-1,2,4-triazole-3-thiones(thioles) 5(a-c). Compounds 5(a-c) were excellent precursors for 3-(arylamino)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazoles 6(a-c) by dehydrative ring closure of the proper triazole with formic acid in benzene in presence of phosphorous oxychloride or using microwave irradiation technique. Also, refluxing of the proper triazoles with carbon disulfide under basic conditions afforded 3-(arylamino)-[1,2,4]triazolo[3,4-b][1,3,4]thiadiazole-6-thiones 7(a-c). Finally 4-amino-3-(4-(5-(4-amino-5-thioxo-4,5-dihydro-1H-1,2,4-triazol-3-ylamino)-1,3,4-thiadiazol-2-yl)phenylamino)-1H-1,2,4-triazole-5(4H)-thione 5(d) were synthesized by the same procedures that were followed to synthesize its analogs starting from 5-(4-aminophenyl)-1,3,4-thiadiazole-2-amine and duplicated all the scales of the reactants. The structures of these compounds were confirmed by their physical properties in addition to the IR, UV and NMR spectra. All synthesized compounds were tested for their in vitro growth inhibitory activity against a panel of standard strains of pathogenic microorganism including bacteria Staphylococcus, Streptococcus and Salmonella. All these compounds were practically inactive against the tested microorganisms.
Highlights
الملخص المواد الوسطية المفتاح لهذه الدراسة لتحضير المركبات الحلقية غير المتجانـسة المهمـة ذات رأس- جسر نتروجين هي Nمعوضات سيمي كاربازيدات ) ،2(a-cوالتي حضرت بهدرزنـة اثيـل معوضـات
INTRODUCTION As part of the continuous program directed toward the synthesis of important heterocyclic compounds, oxygenous and nitrogenous five and six membered rings (Saied et al., 2010), it was became of interest to investigate the preparative routs to synthesize the title fused heterocyclic compounds
It was worthy to mention that semicarbazides converted to carbodithioate salts or cyclized to oxadiazole- 2- thiones by the same reagents, but by two different procedures, while the former involved the agitation at room temperature of the reaction mixture which led to precipitate of quantitative yield of potassium salt which was used in the step without further purification (Joshi et al, 1989)
Summary
الملخص المواد الوسطية المفتاح لهذه الدراسة لتحضير المركبات الحلقية غير المتجانـسة المهمـة ذات رأس- جسر نتروجين هي Nمعوضات سيمي كاربازيدات ) ،2(a-cوالتي حضرت بهدرزنـة اثيـل معوضـات. 1H NMR (DMSO-d6, δ ppm) for ethyl thiazol-5-yl carbamate 1(b) as a representative of these compounds: 11.68 (s, 1H, NH), 7.38 and 7.17(two s, 2H, thiazole ring), 2.12 (q, 2H, CH2) and 1.25(t, 3H, CH3), other physical and spectral data were listed in Table (1).
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
