S-Methyl-(-N-aryl and -N-alkyl)isothioureas derived from 2-aminobenzothiazole (original) (raw)
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The preparation of some fused isothiazole derivatives
Canadian Journal of Chemistry, 1985
The treatment of di(2-amino-5-methylphenyl)methane with N-sulfinylmethanesulfonamide gives two materials, 3-(2-amino-5-methylphenyl)-5-methyl-2,1-benzisothiazole and what appears to be its tautomer, a 2,1-benzisothiazolo[2,3-b]-2,1-benzisothiazole derivative. Reaction of the former with methyl iodide gives mono-, di-, and trimethyl derivatives. The second of these also possesses the symmetrical 2,1-benzisothiazolo[2,3-b]-2,1-benztsothiazole structure. The structure of the other methylation product and of the acetylation products are discussed. Some 1,2-dithiol-3-ylidene-2-pyridylmethanes were made by condensation of 3-alkylthio-1,2-dithiolium salts with methyl 2-pyridylacetate. These demonstrate little sulphur–nitrogen interaction. 3-Methylthio-4-phenyl-1,2-dithiolium iodide reacts anomalously with methyl 2-pyridylacetate to form a quinolizinethione. 1,2-Benzisothiazolo[2,3-a]pyridintum triiodide was made by iodine oxidation of 2-(2-mercaptophenylpyridine).
Isothioureas, Ureas, and Their N-Methyl Amides from 2-Aminobenzothiazole and Chiral Amino Acids
Molecules, 2019
In this investigation, the reaction of 2-dithiomethylcarboimidatebenzothiazole with a series of six chiral amino-acids was studied. The reaction proceeds through the isolable sodium salt of SMe-isothiourea carboxylates as intermediates, whose reaction with methyl iodide in stirring DMF as solvent affords SMe-isothiourea methyl esters. The presence of water in the reaction leads to the corresponding urea carboxylates as isolable intermediates, whose methyl esters were obtained. Finally, the urea N-methyl amide derivatives were isolated when SMe-isothiourea or urea methyl esters were reacted with methylamine in the presence of water. The structures of synthesized compounds were established by 1H and 13C nuclear magnetic resonance and the structures of SMe-isothiourea methyl esters derived from (l)-glycine, (l)-alanine, (l)-phenylglycine, and (l)-leucine, by X-ray diffraction analysis. This methodology allows to functionalize 2-aminobenzothiazole with SMe-isothiourea, urea, and methyla...
Synthesis, Characterization and Antibacterial activity of Benzthiazole derivatives
A parent benzothiazole nucleus was synthesized by para amino acetanilide, then it is subjected to treatment with various substituted aromatic aldehydes to get the corresponding Schiff's bases followed by treatment with pthalic anhydride to form 2-(6-acetamidobenzo[d]thiazol-2ylcarbamoyl)benzoic acid. The structures of synthesized compounds were confirmed by various spectroscopic methods such as IR, 1 H NMR and mass spectroscopy. The products were evaluated for their antibacterial activity. Some of the compounds exhibited potent activity when compared with the standards.
CHEMICAL & PHARMACEUTICAL BULLETIN, 2011
During the last few decades, increased incidence of bacterial resistance to existing drugs has become a major concern throughout the world and necessitates continuing research into new classes of antibiotics. 1) Extensive use of antibacterial drugs and their resistance against bacterial infections has led to severe health problems. Of particular concern are severe infections caused by multidrug-resistant Gram-positive pathogens, such as Staphylococcus species, 2,3) which has become a serious problem in hospitals and in the community. Resistance of wide spectrum antibacterial agents has prompted discovery and modification toward new antibiotics with a potent, wide therapeutic window, broad spectrum activity, and new mode of action. The thiazole scaffold is an interesting building block in a variety of natural products and bioactive compounds that are useful as pharmaceuticals or agrochemical agents. Synthesis of thiazole analogues has attracted continuing interest over the years due to their wide range of pharmaceutical and biological properties, including antibacterial, 4-7) anti-human immunodeficiency virus (HIV), 8) hypertension, 9) anti-inflammatory, 10) anti-viral 11,12) and anticancer 13,14) activity. A survey of the literature also revealed that some new thiazole candidates showed adenosine receptor antagonists 15) and Src family kinase inhibitor activity. 16) More recently, Zhang et al. 17) reported that 2-aminothiazole analogues acted as potential neuroprotective agents for treatment of neurological diseases and Leone et al. 18) reported on modulators of transcriptional repression for treatment of Huntington's disease. The antimicrobial activities of different arylidenehydrazinyl-4-arylthiazoles were also reported. 19,20) Due to the observed wide range of biological activities of the thiazole derivatives and in continuation of our ongoing studies on novel biologically active molecules, we were prompted to design, synthesize, and perform antimicrobial evaluation of 2-arylidenehydrazinyl-4-arylthiazole analogues. Syntheses of desired analogues of 2-arylidenehydrazinyl-4-arylthiazole were carried out according to Hantzsch's method 21) and the structures of the new compounds were elucidated by IR, 1 H-NMR, mass spectrometry, and elemental analysis. In vitro antibacterial activities were screened against eight bacterial strains, e.g Bacillus cereus, Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, Pseudomonas aeruginosa, Shigella dysenteriae, Salmonella typhi, and Escherichia coli. Antifungal activity was determined against three different fungal strains, including Aspergillus oryzae, Candida albicans, and Saccharomyces cerevis. Finally, quantum-chemical and physicochemical calculations were carried out with the ab initio Hartree-Fock model to study the relationship between the electronic properties and antibacterial activity of 2-arylidenehydrazinyl-4arylthiazole analogues. Results and Discussion Synthesis The synthetic routes of arylidenethiosemicarbazones (1a-k) and 2-arylidenehydrazinyl-4-arylthiazoles (2a-k) are outlined in Chart 1. Arylidenethiosemicarbazones (1a-k) were prepared by condensation of thiosemicarbazide and substituted benzaldehyde in ethanol in excellent yield (86-98%). Structures of compounds 1a-k were determined using IR and 1 H-NMR spectral data. IR spectrum
Il Farmaco, 2004
The multistep synthesis of a series of new substituted-benzothiazoles as hydrochloride or quaternary salts is described. 6-Amidino substituted 2-aminobenzothiazoles (5, 6), N-methyl-2-(4-cyanostyryl)benzothiazolium iodide (8), cyano-substituted-2-styrylbenzothiazoles (9-11) and amidino and bis-amidino-substituted 2-styrylbenzothiazoles (12-17) were prepared. The crystal structure of amidino derivative was determined by single crystal X-ray analysis. All new prepared compounds were tested on the cytostatic activities against malignant cell lines: (SW620, colon carcinoma; Hep2, laryngeal carcinoma; HBL, melanoma; HeLa, cervical carcinoma and WI38, human normal fibroblasts). The compounds exerted a different inhibitory effect, depended on concentration and type of the cells. The best inhibitory effect was achieved with compounds (12-15), with slight differences among them. All of them inhibited the growth of examined tumor cell lines and also normal fibroblasts. Other examined compounds exhibited a moderate inhibitory effect, depending on type of the cells. Majority of them inhibited the growth of HeLa cells and WI38.
European Journal of Medicinal Chemistry, 2014
Key compound 2-(4-amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-tiazole-1-yl) acetohydrazide (3) was synthesized by reacting hydrazine hydrate with ethyl-2-(4amino-5-oxo-3-(thiophene-2-ylmethyl)-4,5-dihydro-1,2,4-tiazole-1yl)acetate (2), obtained in basic media from 4-amino-5-(thiophene-2-ylmethyl)-2H-1,2,4-triazole-3(4H)-one (1). Compound 3 was converted to thiosemicarbazide derivatives (4a-d) and Schiff base derivatives 6a-e and 7a-e. The treatment of compound 4 with NaOH gave 4-amino-2-((4-(4aryl)-5-mercapto-4H-1,2,4-triazole-3-yl)methyl)-5-(thiophene-2-ylmethyl)-2H-1,2,4-triazole-3(4H)-ones (5a-d). All newly compounds, well characterized by elemental analyses, IR, 1 H NMR, 13 C NMR and mass spectral studies were tested for their antioxidant and antimicrobial activities. Thiosemicarbazide derivatives (4a-d) were highly active in two antioxidant tests with 69.0-88.2% DPPH• scavenging and 503-1257 µM TEAC values, while the others showed lower or no activity. The results of the two antioxidant tests correlated well. Moreover, Thiosemicarbazide derivatives (4a-d) also showed antibacterial activity against S. aureus, B. cereus, and M. smegmatis. Thiosemicarbazide group deserves attention in the synthesis of bioactive compounds.
Monatshefte für Chemie - Chemical Monthly, 2008
A series of new N-and S-substituted 1,3,4-oxadiazole derivatives were synthesized. 5-Pyridin-3-yl-3-[2-(5-thioxo-4,5-dihydro-l,3,4-thiadiazol-2-yl)ethyl]-1,3,4-oxadiazole-2(3H)-thione and 5-[(5-(pyridin-3-yl)-1,3,4-oxadiazol-2-ylthio)methyl]-Nphenyl-1,3,4-thiadiazol-2-amine were formed by cyclization of 3-(5-pyridin-3-yl-2-thioxo-1,3,4-oxadiazol-3(2H)-ylpropanimidohydrazide and 2-[(5-pyridin-3-yl-1,3,4-oxadiazol-2-yl)thio]thiosemicarbazide with CS 2 and H 2 SO 4 . On the other hand, a number of new bicyclic 1,2,4-triazolo[3,4-b][1,3,4]thiadiazole derivatives were synthesized. 6-Pyridin-3-ylbis[1,2,4]triazolo[3,4-b:4 0 ,3 0 -d][1,3,4]thiadiazole-3(2H)-thione was synthesized by reaction of 6-(hydrazino)-3-pyridine-3-yl[1,2,4]triazolo [3,4-b][1,3,4]thiadiazole with CS 2 =KOH=EtOH. The structures of the newly synthesized compounds were elucidated by the spectral and analytical data IR, Mass, and 1 H NMR spectra.