- A pentaammineruthenium(III) dimer with the novel bridging ligand 4,4′-dicyanamidobiphenyl dianion
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The novel ligand 4,4′-dicyanamidobiphenyl dianion (bp2-) has been synthesized and characterized by 13C NMR spectroscopy, cyclic voltammetry, and crystallography. The crystal structure of [Ph4As]2[bp]·H2O showed that bp2- is approximately planar with a dihedral angle of 8.2° between phenyl ring planes and the cyanamide groups in an ami conformation. The water of crystallization is asymmetrically hydrogen bonded between cyanamide groups of adjacent bp2- ions. The crystal data for C62H48N4As2+H2O are monoclinic crystal system and space group P21/c with a = 12.998(5) A?, b = 13.465(4) A?, c = 28.703(13) A?, β = 98.94(3)°, V = 4963(3) A?3, and Z = 4. The structure was refined by using 4555 reflections with I > 2.5σ(I) to an R factor of 0.058. The complex, [{(NH3}5Ru}2(μ-bp)][X]4, where X = tosylate or PF6- ions, was also synthesized and characterized by 1H NMR spectroscopy, cyclic voltammetry, spectroelectrochemistry, and temperature-dependent magnetic susceptibility measurements. From cyclic voltammetry measurements, the comproportionation constants to form the mixed-valence complex [{(NH3}5Ru)2(μ-bp)]3+ were estimated to be 4.1, 16, and 22 in water, acetonitrile, and nitromethane, respectively. The trend and magnitude of Kc suggests solvent valence trapping of a weakly coupled Class II ion. The MMCT band of the mixed-valence complex had to be deconvoluted from the low-energy LMCT band and had the following properties in acetonitrile, νmax = 8400 cm-1, εmax = 3300 M-1 cm-1, and Δν1/2 = 3300 cm-1. The weak superexchange mediating properties of bp2- compared to 1,4-dicyanamidobenzene dianion were suggested to arise from the larger barrier to the formation of the radical anion bp-.
- Aquino, Manuel A.S.,White, Christopher A.,Bensimon, Corinne,Greedan,Crutchley, Robert J.
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Read Online
- N-benzoylthiourea
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In the title compound, C8H8N2OS, strong intramolecular N - H...O hydrogen bonds [N...O = 2.669 (3) and 2.618 (3) A] form almost planar six-membered rings and enforce the conformation of the molecule. Two kinds of intermolecular N-H...S hydrogen bonds [N...S = 3.309 (3)-3.456 (2) A] between two symmetry-independent molecules form consecutive dimers that expand in ribbons along the [100] direction.
- Wagner, Pawel,Niemczyk-Baltro, Sabina,Kubicki, Maciej
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Read Online
- Iodine-mediated multi-component reactions: Readily access to tetrazoles and guanidines
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Environmentally benign syntheses of One-pot sequential reactions of benzoyl chloride with amines followed by the treatment of molecular I2 reagent under basic conditions provide benzoyl tetrazoles and guanidines in moderate to excellent yields. This one-pot synthesis has several advantages such as mild reaction conditions, short reaction time, convenient workup, high yields, using cheap and readily available reagent molecular Iodine. In addition, functional group tolerance has been explored.
- Kammela, Prasad Rao,Seelam, Mohan,Shaik, Bajivali,Tamminana, Ramana
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p. 382 - 388
(2021/09/07)
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- Synthesis and structure-activity relationship studies of n-monosubstituted aroylthioureas as urease inhibitors
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Background: Thiourea is a classical urease inhibitor which is usually used as a positive control, and many N,N'-disubstituted thioureas have been determined as urease inhibitors. However, due to steric hindrance, N,N'-disubstituted thiourea motif could not bind urease as thiourea. On the contrary, N-monosubstituted thiourea with a tiny thiourea motif could theoretically bind into the active pocket as thiourea. Objective: A series of N-monosubstituted aroylthioureas were designed and synthesized for evaluation as urease inhibitors. Methods: Urease inhibition was determined by the indophenol method and IC50 values were calculated using computerized linear regression analysis of quantal log dose-probit functions. The kinetic parameters were estimated via surface plasmon resonance (SPR) and by nonlinear regression analysis based on the mixed type inhibition model derived from Michaelis-Menten kinetics. Results: Compounds b2, b11, and b19 reversibly inhibited urease with a mixed mechanism, and showed excellent potency against both cell-free urease and urease in the intact cell, with IC50 values being 90-to 450-fold and 5-to 50-fold lower than the positive control acetohydroxamic acid, respectively. The most potent compound b11 showed an IC50 value of 0.060 ± 0.004μM against cell-free urease, which bound to urea binding site with a very low KD value (0.420±0.003nM) and a very long residence time (6.7 min). Compound b11 was also demonstrated to have very low cytotoxicity to mammalian cells. Conclusion: The results revealed that N-monosubstituted aroylthioureas bound to the active site of urease as expected, and represent a new class of urease inhibitors for the development of potential therapeutics against infections caused by urease-containing pathogens.
- Dawalamu,Fang, Hai-Lian,Fu, Zi-Juan,Li, Fang,Li, Ke,Li, Wei-Yi,Liu, Li,Ni, Wei-Wei,Ouyang, Hui,Xiao, Zhu-Ping,Ye, Ya-Xi,Zhu, Hai-Liang,Zhu, Wen-Yan,Zou, Xia
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p. 1046 - 1059
(2021/11/30)
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- ω-Quinazolinonylalkyl aryl ureas as reversible inhibitors of monoacylglycerol lipase
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The serine hydrolase monoacylglycerol lipase (MAGL) is involved in a plethora of pathological conditions, in particular pain and inflammation, various types of cancer, metabolic, neurological and cardiovascular disorders, and is therefore a promising target for drug development. Although a large number of irreversible-acting MAGL inhibitors have been discovered over the past years, there are only few compounds known so far which inhibit the enzyme in a reversible manner. Therefore, much effort is put into the development of novel chemical entities showing reversible inhibitory behavior, which is thought to cause less undesired side effects. To explore a wide range of chemical structures as MAGL binders, we have applied a virtual screening approach by docking small molecules into the crystal structure of human MAGL (hMAGL) and envisaged a library of 45 selected compounds which were then synthesized. Biochemical investigations included the determination of the inhibitory potency on hMAGL and two related hydrolases, i.e. human fatty acid amide hydrolase (hFAAH) and murine cholesterol esterase (mCEase). The most promising candidates from theses analyses, i.e. three ω-quinazolinonylalkyl aryl ureas bearing alkyl spacers of three to five methylene groups, exhibited IC50 values of 20–41 μM and reversible, detergent-insensitive behavior towards hMAGL. Among these compounds, the inhibitor 1-(3,5-bis(trifluoromethyl)phenyl)-3-(4-(4-oxo-3,4-dihydroquinazolin-2-yl)butyl)urea (96) was selected for further kinetic characterization, yielding a dissociation constant Ki = 15.4 μM and a mixed-type inhibition with a pronounced competitive component (α = 8.94). This mode of inhibition was further supported by a docking experiment, which suggested that the inhibitor occupies the substrate binding pocket of hMAGL.
- Dato, Florian M.,Neud?rfl, J?rg-Martin,Gütschow, Michael,Goldfuss, Bernd,Pietsch, Markus
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supporting information
(2019/11/13)
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- Identification of novel thiourea-stilbene-triazine conjugates as persuasive lymphoid tyrosine phosphatase inhibitors
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A library of novel thiourea-based symmetrical stilbene-triazines (5a-i) was synthesized in an effort to develop new protein tyrosine phosphatase LYP inhibitors. The versatile nature of 2,4,6-trichloro-1,3,5-triazine allows considerable scope for derivatization and hence exploration of structure activity relationships. A convenient and versatile three-step synthetic approach involved the successive replacement of the two chloro groups of 2,4,6-trichloro-1,3,5-triazine by a variety of substituents for structural modification. The newly synthesized derivatives were subjected to tyrosine phosphatase LYP inhibition studies. The results for the in vitro bioassays were promising with the identification of compound 5k and 5l having a 4-methyl and 4-methoxy substituent on phenyl ring, as the lead and selective candidate for LYP inhibition with an IC50 value of 2.1 ± 0.05 μM and 28 ± 3.3 μM, respectively. Moreover, docking studies were carried out to determine the possible interaction sites of thiourea-based stilbene-triazine compounds with Lymphoid Tyrosine Phosphatase. Results of docking computations further ascertained the inhibitory potential of compound 5k and 5l. The results indicated that the compound 5k may serve as a structural model for the design of most potent LYP inhibitors.
- Batool, Iram,Jabeen, Farukh,Saeed, Aamer,Shabir, Ghulam,Vellore, Nadeem Ahmed
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p. 3400 - 3411
(2020/08/19)
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- Benzoylthioureas: Design, synthesis and antimycobacterial evaluation
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Background: New drugs and strategies to treat tuberculosis (TB) are urgently needed. In this context, thiourea derivatives have a wide range of biological activities, including anti-TB. This fact can be illustrated with the structure of isoxyl, an old anti-TB drug, which has a thiourea as a pharmacophore group. Objective: The aim of this study is to describe the synthesis and the antimycobacterial activity of fifty-nine benzoylthioureas derivatives. Methods: Benzoylthiourea derivatives have been synthesized and evaluated for their activity against Mycobacterium tuberculosis using the MABA assay. After that, a structure-activity relationship study of this series of compounds has been performed. Results and Discussion: Nineteen compounds exhibited antimycobacterial activity between 423.1 and 9.6 μM. In general, we observed that the presence of bromine, chlorine and t-Bu group at the para-position in benzene ring plays an important role in the antitubercular activity of Series A. These substituents were fixed at this position in benzene ring and other groups such as Cl, Br, NO2 and OMe were introduced in the benzoyl ring, leading to the derivatives of Series B. In general, Series B was less cytotoxic than Series A, which indicates that the presence of a substituent at benzoyl ring contributes to an improvement in both antimycobacterial activity and toxicity profiles. Conclusion: Compound 4c could be considered a good prototype to be submitted to further structural modifications in the search for new anti-TB drugs, since it is 1.8 times more active than the first line anti-TB drug ethambutol and 0.65 times less active than isoxyl.
- Abreu, Lethícia O.,Bispo, Marcelle L. F.,Brito, Tiago O.,Gomes, Karen M.,Louren?o, Maria C. S.,Macedo, Fernando,Pereira, Patricia M. L.,Tisher, Cesar A.,Yamada-Ogatta, Sueli F.,de Fátima, ?ngelo
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- Catalytic Assessment of Copper(I) Complexes and a Polymer Analog towards the One-Pot Synthesis of Imines and Quinoxalines
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Three copper(I) complexes, [CuCl(L)(PPh3)2] [L = FL (1), BL (2) or TL (3)] were prepared from [(PPh3)2Cu(μ-Cl)2Cu(PPh3)] and N-carbamothioylfuran-2-carboxamide (FL), N-carbamothioylbenzamide (BL) or N-carbamothioylthiophene-2-carboxamide (TL) ligands in benzene and four-coordinated tetrahedral copper complexes were well characterized by various spectroscopic techniques (UV/Vis, FT-IR, 1H NMR, 13C NMR and 31P NMR). The molecular structure of the ligands (FL and BL) and complexes was established from single-crystal X-ray diffraction studies. Copper complexes have been shown to catalyse the one-pot synthesis of imines and quinoxalines. Heterogenized catalyst (4) was prepared by reacting more active complex 3 with polystyrene supported triphenylphosphane, and characterized by elemental analyses, and DRS-UV, FT-IR, ICP-OES, and solid-state NMR techniques. Catalytic activity of the complexes (3 and 4) was tested in the formation of imines from alcohols and amines, and quinoxalines from hydroxy ketones and diamines. Heterogeneity and reusability of catalyst 4 were evaluated, and the catalyst can be reused for four runs without any loss in activity.
- Sindhuja, Dharmalingam,Vasanthakumar, Punitharaj,Bhuvanesh, Nattamai,Karvembu, Ramasamy
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p. 3588 - 3596
(2019/08/20)
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- Chalcone-Thiazole Hybrids: Rational Design, Synthesis, and Lead Identification against 5-Lipoxygenase
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A hybrid pharmacophore approach is used to design and synthesize novel chalcone-thiazole hybrid molecules. Herein, thiazole has been hybridized with chalcone to obtain a new class of 5-LOX inhibitors. In vitro biological evaluation showed that most of the compounds were better 5-LOX inhibitors than the positive control, Zileuton (IC50 = 1.05 ± 0.03 μM). The best compounds in the series, namely, 4k, 4n, and 4v (4k: IC50 = 0.07 ± 0.02 μM, 4n: IC50 = 0.08 ± 0.05 μM, 4v: 0.12 ± 0.04 μM) are found to be 10 times more active than previously reported 2-amino thiazole (2m: IC50 = 0.9 ± 0.1 μM) by us. Further, 4k has redox (noncompetitive) while 4n and 4v act through a competitive inhibition mechanism. SAR indicated that the presence of methoxy/methyl either in the vicinity of chalcone or both thiazole and chalcone contributed to the synergistic inhibitory effect.
- Doble, Mukesh,Manju, S. L.,Sinha, Shweta
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supporting information
(2019/10/08)
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- Design, syntheses and evaluation of benzoylthioureas as urease inhibitors of agricultural interest
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Urea is one of the most used nitrogen fertilizers worldwide. However, occurrence of urea hydrolysis to ammonia and carbon dioxide on soil surface, catalyzed by soil ureases, considerably reduces nitrogen availability to crops. In this study, we describe the design, synthesis and screening of sixty five benzoylthioureas (BTUs) for their ability to inhibit purified jack bean and soil ureases. BTUs were readily obtained in one pot, two steps synthesis with no need of cumbersome procedures for product purification. In vitro assays revealed BTUs 11, 12, 14, 19-22 and 37 as the most active jack bean urease inhibitors. Such BTUs were found to be able to bind to both catalytic and allosteric sites of urease, acting therefore as mixed-type inhibitors. Out of 28 compounds that effectively inhibited soil ureases activity, BTUs 3, 6, 10, 12, 16, 19 and 22 were determined to be more potent than the reference inhibitor N-(butyl) thiophosphoric triamide (NBPT; 40%). The other 22 BTUs were as potent as NBPT on soil ureases. The temperature-tolerance of BTUs, along with their ability to inhibit soil ureases, makes of this class of compounds potential additive for urea-based fertilizers.
- Brito, Tiago O.,Souza, Aline X.,Mota, Yane C. C.,Morais, Vinicius S. S.,De Souza, Leandro T.,De Fátima, ?ngelo,Macedo, Fernando,Modolo, Luzia V.
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p. 44507 - 44515
(2015/06/02)
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- ACCELERATORS FOR CURABLE COMPOSITIONS
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Benzoylthiourea or benzoylthiourethane derivatives as cure accelerators for curable compositions are provided.
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Paragraph 0049
(2014/01/17)
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- ACCELERATORS FOR TWO PART CURABLE COMPOSITIONS
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Benzoylthiourea or benzoylthiourethane derivatives as cure accelerators for two part curable compositions are provided.
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Paragraph 0049
(2014/01/17)
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- Synthesis, supramolecular structure, antimicrobial and plant-growth regulation activities of n-benzoylthiourea
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N-Benzoylthiourea has been synthesized and characterized by elemental analysis, IR and 1H NMR etc. The X-ray crystallography of the compound indicates that the carbonyl group forms an intramolecular hydrogen bond with the N2-H2 group, which forms a six-membered ring (C7/N1/C8/N2/H2/O1) srtucture. Each molecule are linked by the intermolecular N2-H2A...S2 and N4-H4A...S1 hydrogen bonds to form a dimer, adjacent dimers are linked by the intermolecular N1-H1N...S2 and N3-H3N...S1 hydrogen bonds, leading to a hydrogenbonded netty structure. The results indicated that the N-benzoylthiourea played the important role in plant-growth regulators and may be a potential source of active antimicrobial agents.
- Zhao, Meng-Meng,Dong, Xiu-Yan,Yang, U-Hua,Li, Gang,Zhang, U-Jie
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p. 237 - 240
(2014/03/21)
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- Antituberculosis and antifungal activities of synthesized, benzoylthiourea derivatives
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A series of benzoylthiourea derivatives have been synthesized from benzoyl isothiocyanate and phenyleneamine in CH2Cl2 medium under solid-liquid phase transfer catalysis conditions. Structures of these compounds have been characterized by elemental analyses as well as IR and 1H NMR spectroscopy. All the compounds were tested for their antibacterial and antifungal activities, the results indicated that most of the compounds have antibacterial and antifungal activities close to the standard drugs, especially they were found to have remarkable antituberculosis and antifungal activities.
- Zhao, Meng-Meng,Dong, Xiu-Yan,Li, Gang,Yang, Yu-Hua,Zhang, Yu-Jie,Yang, Xiao-Qin
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p. 7548 - 7550
(2013/08/23)
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- Design and synthesis of a hybrid potentiator-corrector agonist of the cystic fibrosis mutant protein ΔF508-CFTR
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A developing therapy of cystic fibrosis caused by the ΔF508 mutation in CFTR employs correction of defective CFTR chloride channel gating by a 'potentiator' and of defective CFTR protein folding by a 'corrector'. Based on SAR data for phenylglycine-type potentiators and bithiazole correctors, we designed a hybrid molecule incorporating an enzymatic hydrolysable linker to deliver the potentiator (PG01) fragment 2 and the corrector (Corr-4a) fragment 13. The hybrid molecule 14 contained PG01-OH and Corr-4a-linker-CO2H moieties, linked with an ethylene glycol spacer through an ester bond. The potentiator 2 and corrector 13 fragments (after cleavage) had low micromolar potency for restoration of ΔF508-CFTR channel gating and cellular processing, respectively. Cleavage of hybrid molecule 14 by intestinal enzymes under physiological conditions produced the active potentiator 2 and corrector fragments 13, providing proof-of-concept for small-molecule potentiator-corrector hybrids as a single drug therapy for CF caused by the ΔF508 mutation.
- Mills, Aaron D.,Yoo, Choong,Butler, Jeffrey D.,Yang, Baoxue,Verkman,Kurth, Mark J.
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scheme or table
p. 87 - 91
(2010/04/05)
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- Clobenpropit analogs as dual activity ligands for the histamine H3 and H4 receptors: Synthesis, pharmacological evaluation, and cross-target QSAR studies
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Previous studies have demonstrated that clobenpropit (N-(4-chlorobenzyl)-S-[3-(4(5)-imidazolyl)propyl]isothiourea) binds to both the human histamine H3 receptor (H3R) and H4 receptor (H4R). In this paper, we describe the synthesis and pharmacological characterization of a series of clobenpropit analogs, which vary in the functional group adjacent to the isothiourea moiety in order to study structural requirements for H3R and H4R ligands. The compounds show moderate to high affinity for both the human H3R and H4R. Furthermore, the changes in the functional group attached to the isothiourea moiety modulate the intrinsic activity of the ligands at the H4R, ranging from neutral antagonism to full agonism. QSAR models have been generated in order to explain the H3R and H4R affinities.
- Lim, Herman D.,Istyastono, Enade P.,van de Stolpe, Andrea,Romeo, Giuseppe,Gobbi, Silvia,Schepers, Marjo,Lahaye, Roger,Menge, Wiro M.B.P.,Zuiderveld, Obbe P.,Jongejan, Aldo,Smits, Rogier A.,Bakker, Remko A.,Haaksma, Eric E.J.,Leurs, Rob,de Esch, Iwan J.P.
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experimental part
p. 3987 - 3994
(2009/10/02)
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- 4′-Methyl-4,5′-bithiazole-based correctors of defective ΔF508-CFTR cellular processing
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The synthesis and ΔF508-CFTR corrector activity of a 148-member methylbithiazole-based library are reported. Synthetic routes were devised and optimized to generate methylbithiazole analogs in four steps. Corrector potency and efficacy were assayed using epithelial cells expressing human ΔF508-CFTR. These structure-activity data establish that the bithiazole substructure plays a critical function; eight novel methylbithiazole correctors were identified with low micromolar potencies.
- Yoo, Choong Leol,Yu, Gui Jun,Yang, Baoxue,Robins, Lori I.,Verkman,Kurth, Mark J.
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p. 2610 - 2614
(2008/12/21)
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- A facile synthesis of substituted N-benzoylthiourea
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One pot reaction of benzoyl isothiocyanate and Tris(hydroxymethyl)aminomethane (Tris) at room temperature with polyethylene glycol-400 (PEG-400) as solid-liquid phase-transfer catalyst produced substituted N-benzoylthioureas with high yield. A reasonable pathway for their formation has been suggested.
- Xu, Xiaoyong,Zhongli,Yang, Zhengyu,Chen, Gang,Qian, Xuhong
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p. 2585 - 2592
(2007/10/03)
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- THERMOLYSIS AND PHOTOLYSIS OF SOME THIOUREA DERIVATIVES (PART I)
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Thermolysis od N-benzoyl-N'-phenylthiourea (BPTU) on heating in air at 230 deg C gives NH3, H2S, benzaldehyde, benzil, aniline, azobenzene, benzamide, benzanilide, phenylisothiocyanate, phenylcyanamide, thiocarbanilide and benzoylisothiocyanate, whereas thermolysis of N-benzoyl-N'-benzylthiourea (BBTU) affords NH3, H2S, benzaldehyde, benzil, toluene, bibenzyl, stilbene, benzamide, cyanamide, benzylisothiocyanate, benzoylthiourea and benzoylisothiocyanate.Thermolysis of N-benzoyl-N'-α-naphthylthiourea (BNTU) under the same conditions gives NH3, H2S, benzaldehyde, benzil, benzamide, α-naphthylisothiocyanate, α-naphthanilide, α-naphthylcyanamide, benzoylisothiocyanate, α-naphthylamine and N,N'-di-α,α'-naphthylthiourea.Analogous results were also obtained on photolysis of (BPTU), (BBTU) and (BNTU) with the exception of NH3 and the photodegradation products of phenylthiourea, benzylthiourea and α-naphthylthiourea respectively.The main feature of these pyrolyses is the homolysis of the amide and thioamide bonds providing free radicals that undergo different reactions involving H-abstraction, dimerization, coupling, fragmentation, rearrangement and disproportionation to yield the identified products.
- Aly, M. M.,Fahmy, A. M.,Gaber, A. M.
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p. 253 - 258
(2007/10/02)
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- Substituted guanidinedicarbonyl derivatives
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This disclosure describes novel substituted guanidinedicarbonyl derivatives which possess anxiolytic activity and are also useful as agents for the treatment of cognitive and related neural behavioral problems in mammals.
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- REACTIONS OF 1,3-DIACYLTHIOUREAS WITH METHOXIDE ION AND WITH AMINES
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Rate constants of base-catalyzed methanolysis and dissociation constants in methanol have been determined for benzylthiourea (II), 1,3-diacetylthiourea (III), 1,3-dibenzoylthiourea (IV), and 1-acetyl-3-benzoylthiourea (V).With the diacyl derivatives III and IV, the reaction of methoxide ion with the neutral substrate is accompanied by that of methoxide with the substrate anion (at higher alkoxide concentrations).Above 0.1 mol l-1 CH3O(-), the rate constants are also affected by medium.The rate of the reaction of neutral diacyl derivative is decreased, and that of the reacti on of methoxide with the substrate anion is rapidly increased.The dissociation constant of II is higher than that of acetylthiourea (I) by about one order of magnitude, but the attack of methoxide on the carbonyl group of II is about three times slower than that in I.The benzoyl group at the N1 nitrogen exhibits a greater activating influence (in both the rate and the equilibrium constants) on the other NHCOR group than the acetyl group does.With V the ratio of methanolysis rate constants is 9:1 in favour of the acetyl group.The reaction of diacetyl derivative III with 1-butanamine has been followed in butanamine buffers.At the lowest butanamine concentrations, the reaction is second order in the amine, and the rate-limiting step is the proton transfer from the intermediate to the second amine molecule.At the highest butanamine concentrations the reaction becomes first order in the amine, and the rate limiting step changes to the attack of butanamine on the carbonyl group of diacetyl derivative III.
- Kavalek, Jaromir,Jirman, Josef,Sterba, Vojeslav
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p. 120 - 131
(2007/10/02)
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- Substituted 5-Imino-3,3-pentamethylene-1,2,4-thiadiazolidines by Amination of Thiourea Derivatives
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N-Acylthioureas 2a-b and thiosemicarbazones of aldehydes, ketones, and esters 4a-g are aminated at the potential SH-group by 3,3-pentamethyleneoxaziridine yielding substituted 5-imino-3,3-pentamethylene-1,2,4-thiadiazolidines 3 and 6 the latter via the intermediates 5.The reaction of the thiosemicarbazones 4 is a very general one, but only two acylthioureas 2 could be converted into the title compounds.
- Andreae, Siegfried,Schmitz, Ernst
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p. 1008 - 1014
(2007/10/02)
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- Reaction of β-Nitro Enamines with Isocyanates, Isothiocyanates and Dimethyl Acetylenedicarboxylate
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β-Nitro enamines (1) reacted with isocyanates and isothiocyanates to give β-(substituted carbamoyl) and β-(substituted thiocarbamoyl) β-nitro enamines, respectively.The reaction of 1 with benzoyl isothiocyanate gave β-(benzoylthiocarbamoyl) β-nitro enamines (8) and/or a mixture of 8 and 4(1H)-pyrimidinethione derivatives (9), which were cyclization products of 8.The isolated 8 afforded the corresponding 9 in high yields upon heating in DMF.The reaction of 1 with dimethyl acetylenedicarboxylate gave cycloadducts (12) and/or a mixture of 12 and δ-nitro dienamino diesters (13) which were ring cleavage products of 12.Compounds 12 afforded 13 upon heating in toluene or xylene.
- Tokumitsu, Takao
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p. 3871 - 3876
(2007/10/02)
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- 1,2,4-Thiadiazolylureas. A Postcript to the Oxidative Cyclisation of Thionoamidines
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The identity of authentic 5-phenyl-3-ureido-1,2,4-thiadiazole synthesized from the pre-formed heterocycle, and of the product of the oxidative cyclisation of N1-carbamoyl-N3-thiobenzoylguanidine, confirms the structure of 5-substituted-3-ureido-1,2,4-thiadiazoles obtained by either route.
- Kurzer, Frederick
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p. 311 - 314
(2007/10/02)
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- CYCLIZATION KINETICS AND MECHANISM OF N-BENZOYL-N'-(1,2-DIMETHYL-3-OXO-1-BUTENYL)THIOUREA
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Cyclization kinetics of N-benzoyl-N'-(1,2-dimethyl-3-oxo-1-butenyl)thiourea have been studied in aqueous and methanolic solutions of acids and bases.In all cases the cyclization product is 4,5,6-trimethyl-2,5-dihydro-2-thioxopyrimidine or its protonated or deprotonated forms.In dilute methanolic and aqueous hydrochloric acid the substrate reacts in its monoprotonated form.The cyclization in basic media is catalyzed by methoxide or hydroxyl ion and also by primary and secondary amines at such pH values were the catalysis by lyate ion is practically insignificant.Tertiary amines and acetate ion do not catalyze the cyclization.
- Kavalek, Jaromir,Potesil, Tomas,Sterba, Vojeslav
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p. 578 - 585
(2007/10/02)
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- KINETICS OF HYDROLYSIS AND REARRANGEMENTS OF S-ACYLTHIOURONIUM SALTS
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Kinetics of transformation of S-acetyl- and S-benzoylisothiouronium chlorides have been followed, and its reaction products in dilute hydrochloric acid media and aqueous buffers have been identified.In dilute hydrochloric acid the reaction rate is pH-independent, and the acetyl derivative reacts 8 times as rapidly as the benzoyl derivative.In acetate and phosphate buffers the decomposition rate of the both derivatives increases linearly with the buffer concentration.In acetate buffers the reaction rate is pH-independent, and acetate ion reacts as a nucleophile, In phosphate buffers the rate increases with increasing pH.The reaction catalyzed by the basic buffer component produces thiourea and carboxylic acid, that catalyzed by hydroxyl ion produces N-acetyl- or N-benzoylthiourea.The solvolysis rates of the both S-acyl derivatives depend on percent composition of water-methanol solvent.The maximum solvolysis rate is reached in methanol with 25percent (v/v) water.
- Kavalek, Jaromir,Novak, Jaroslav,Sterba, Vojeslav
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p. 2702 - 2710
(2007/10/02)
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