- 4-PHENYL-N-(PHENYL)THIAZOL-2-AMINE DERIVATIVES AND RELATED COMPOUNDS AS ARYL HYDROCARBON RECEPTOR (AHR) AGONISTS FOR THE TREATMENT OF E.G. ANGIOGENESIS IMPLICATED OR INFLAMMATORY DISORDERS
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4-phenyl-N-(phenyl)thiazol-2-amine and 4-(pyridin-3-yl)-N-( phenyl) thiazol-2-amine derivatives and the corresponding thiadiazole, thiophene, oxazole, oxadiazole, imidazole and triazole derivatives and related compounds as aryl hydrocarbon receptor (AHR) agonists for the treatment of angiogenesis implicated disorders, such as e.g. retinopathy, psoriasis, rheumatoid arthritis, obesity and cancer, or inflammatory disorders.
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Paragraph 00221; 00311-00312
(2021/06/26)
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- Eco-efficient one-pot tandem synthesis of 1-aryl-1H-tetrazol-5-amine by CAN via in situ generated 1-phenylthiourea and heterocumulene
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A simple, cost-effective, environmentally benign, and efficient one-pot tandem approach to the synthesis of pharmaceutically important 1-aryl-1H-tetrazole-5-amines 3a-k and 4a-k has been described. The reaction utilized 1-phenyl thiourea, which was generated in situ from aqueous ammonia and isocyanates 1a-k, for the formation of heterocumenes using sodium azide, triethylamine, and ceric ammonium nitrate (CAN) to obtain various aryl-substituted 1H-tetrazole-5-amines (3a-k) in good to excellent yields.
- Kondhare, Dasharath D.,Bhadke, Venkat V.,Deshmukh, Sushma S.,Wakhradkar, Mahesh G.,Totawar, Balaji B.
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- Design, synthesis and antimicrobial study of novel 1-(1,3-benzothiazol-2-yl)-3-chloro-4H-spiro[azetidine-2,3'-indole]-2',4(1'H)-diones through ketene–imine cycloaddition reaction
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The present study deals with the synthesis of novel 1-(1,3-benzothiazol-2-yl)-3-chloro-4H-spiro[azetidine-2,3'-indole]-2',4(1'H)-dione derivatives from the reaction of 3-(1,3-benzothiazol-2-ylimino)-1,3-dihydro-2H-indol-2-one derivatives with chloroacetyl chloride in the presence of triethyl-amine (TEA). The mechanism involved simple acid or base catalysed reaction through the formation of Schiff base followed by cyclisation via ketene–imine cycloaddition reaction. All synthesized compounds were characterized by FT-IR,1H-NMR,13C-NMR, and elemental analysis. The antimicrobial activities of the synthesized derivatives 5a-5g were examined via Micro Broth Dilution method against bacterial strains Bacillius subtilis, Staphylcoccus aureus, E. coli, P. aeruginosa, and fungal strain Candida albicans for determining MIC values. Ampicillin, chloramphenicol, and griseofulvin were used as standard drugs. The MIC values for antimicrobial activity of synthesized compounds were examined using Micro Broth Dilution method. Compounds 5a, 5b, and 5c were found effective against E. coli (MTCC 442) and P.aeruginosa (MTCC 441) and all compounds showed moderate to excellent activity against Streptococcus aureus (MTCC 96) and Bacillius subtilis (MTCC 441). Regarding the antifungal screening, compounds 5a, 5b, and 5c exhibited excellent activity against Candida albicans MTCC 227. 1-(1,3-benzothiazol-2-yl)-3-chloro-4H-spiro[azetidine-2,3'-indole]-2',4(1'H)-dione derivatives may be used as potential lead molecules as effective antimicrobial agents.
- Agarwal, Dinesh Kr.,Agarwal, Shikha,Gandhi, Divyani,Prajapat, Prakash,Sethiya, Ayushi
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p. 141 - 148
(2020/02/04)
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- A novel one-pot synthesis of isothiocyanates and cyanamides from dithiocarbamate salts using environmentally benign reagent tetrapropylammonium tribromide
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A highly efficient and simple protocol for the synthesis of isothiocyanates and cyanamides from their respective amines in the presence of a mild, efficient, and non-toxic reagent tetrapropylammonium tribromide is described. High environmental acceptability of the reagents, cost effectiveness and high yields are the important attributes of this methodology.
- Kuotsu, Neivotsonuo Bernadette,Jamir, Latonglila,Phucho, Tovishe,Sinha, Upasana Bora
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p. 832 - 841
(2018/01/17)
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- Double three bromo 1,3-di-pyridine salt-based propane and its preparation method, method of use, recovery method and application
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The invention discloses a double tribromo 1,3-bipyridine onium salt dimethylmethane, and a preparation method, an application method, a recovery method and application thereof. The preparation method comprises the following steps: dissolving 1,3-bipyridine onium salt dimethylmethane by using water, and then adding potassium bromide; adding potassium peroxymonosulfate sulfate compound brine solution to prepare a clear solution after dissolving potassium bromide, and then stirring and reacting at -10 to 0 DEG C until solid is separated out; separating out solid, so as to obtain the double tribromo 1,3-bipyridine onium salt dimethylmethane. The product can be used for preparing isothiocyanate, aromatic thiourea or acetanilide. The preparation method disclosed by the invention is mild in condition, and simple to operate the reaction process, and raw materials are easily available. The double tribromo 1,3-bipyridine onium salt dimethylmethane not only can be used as a brominating reagent, but also can be used as organic synthesis intermediates, meanwhile, the reaction efficiency is improved, and the double tribromo 1,3-bipyridine onium salt dimethylmethane is convenient to recover and can be recycled.
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Paragraph 0215; 0216
(2016/10/07)
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- Synthesis of monosubstituted thioureas by vapour digestion and mechanochemical amination of thiocarbamoyl benzotriazoles
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Thiocarbamoyl benzotriazoles, as safe and easy-to-handle isothiocyanate equivalents, were quantitatively converted to N-monosubstituted thioureas by vapour digestion synthesis under an ammonia atmosphere. This simple, but timely process provided a synthetic platform that enabled the "slow" amination reaction to be successfully transformed into a rapid one aided by mechanochemical milling. The ammonium chloride/sodium carbonate equimolar mixture allowed in situ formation of ammonia under ball-milling conditions. This novel and green approach yielded aromatic and aliphatic primary thioureas in near-quantitative isolated yields with workup entirely based on using only water. In addition, the molecular and crystal structures of selected polyaromatic primary thioureas were determined from the synchrotron powder diffraction data.
- Dud, Mateja,Magdysyuk, Oxana V.,Margeti?, Davor,?trukil, Vjekoslav
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p. 2666 - 2674
(2016/05/24)
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- PHENYLIMIDE-CONTAINING BENZOTHIAZOLE DERIVATIVE OF ITS SALT AND PHARMACEUTICAL COMPOSITION COMPRISING THE SAME
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Provided is a phenylimide-containing benzothiazole derivative or its pharmaceutically acceptable salt, a process for the preparation thereof, and a pharmaceutical composition comprising the same. The phenylimide-containing benzothiazole derivative or its pharmaceutically acceptable salt can selectively inhibit the protein-protein interaction between KRS and a laminin receptor (LR), thereby inhibiting migration of cancer cells. Therefore, the phenylimide-containing benzothiazole derivative or its pharmaceutically acceptable salt may be usefully applied for preventing or treating the diseases associated with cancer cell metastasis.
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Paragraph 0187
(2015/02/18)
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- PHENYLIMIDE-CONTAINING BENZOTHIAZOLE DERIVATIVE OR ITS SALT AND PHARMACEUTICAL COMPOSITION COMPRISING THE SAME
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The present invention provides a phenylimide-containing benzothiazole derivative or its pharmaceutically acceptable salt, a process for the preparation thereof, and a pharmaceutical composition comprising the same. The phenylimide-containing benzothiazole derivative or its pharmaceutically acceptable salt can selectively inhibit the protein-protein interaction between KRS and a laminin receptor (LR), thereby inhibiting migration of cancer cells. Therefore, the phenylimide-containing benzothiazole derivative or its pharmaceutically acceptable salt may be usefully applied for preventing or treating the diseases associated with cancer cell metastasis.
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Paragraph 241; 242
(2013/04/10)
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- Biochemical and pharmacological evaluation of 4-hydroxychromen-2-ones bearing polar C-3 substituents as anticoagulants
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The objective of this study was to investigate in vitro and in vivo anticoagulant activity of sixteen 4-hydroxycoumarin derivatives bearing polar C-3 scaffolds. The activity was evaluated by measuring prothrombin time. Enhanced anticoagulant activity in vitro was observed for all tested compounds. Upon successive administration of 0.5 mg/kg of body weight to adult Wistar rats, over a period of five days, four derivatives (2b, 4c, 5c and 9c) presented anticoagulant activity in vivo. The most active compound was 2b, with PT = 30.0 s. Low or non-toxic effects in vivo were determined based on the catalytic activity of liver enzymes and the concentration of bilirubin, iron and proteins. Metabolic pathways of the most active compounds in vivo were determined after GC/MS analysis of collected rat urine samples. The excretion occurs by glucuronidation of 7-hydroxy forms of tested derivatives. In vivo results were described using PLS-based CoMFA and CoMSIA 3D-QSAR studies, which showed CoMFA-SE (q2 = 0.738) and CoMSIA-SEA (q2 = 0.763) to be the statistically most relevant models. Furthermore, molecular docking and DFT mechanistic studies performed on the rat VKORC1 homology model revealed interactions between the 4-OH coumarin group in the form of phenolic anion and the Cys135 catalytic site in the transition state.
- Mladenovic, Milan,Mihailovic, Mirjana,Bogojevic, Desanka,Vukovic, Nenad,Sukdolak, Slobodan,Matic, Sanja,Niciforovic, Neda,Mihailovic, Vladimir,Maskovic, Pavle,Vrvic, Miroslav M.,Solujic, Slavica
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scheme or table
p. 144 - 158
(2012/09/21)
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- Environmentally benign one-pot synthesis of cyanamides from dithiocarbamates using I2 and H2O2
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An environmentally benign reaction is devised for the synthesis of cyanamides from dithiocarbamate salts using iodine and H2O 2. Taylor & Francis Group, LLC.
- Jamir, Latonglila,Sinha, Upasana Bora,Nath, Jayashree,Patel, Bhisma K.
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p. 951 - 958
(2012/02/01)
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- Bromineless bromine as an efficient desulfurizing agent for the preparation of cyanamides and 2-aminothiazoles from dithiocarbamate salts
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In a one-pot procedure, bromineless brominating reagent 1,1'-(ethane-1,2-diyl)dipyridinium bistribromide (EDPBT) has been used as a desulfurizing agent in the preparation of organic cyanamides and substituted thiazoles starting from dithiocarbamic acid salts. In this approach, alkyl/aryl isothiocyantes were first obtained by the desulfurization of dithiocarbamic acid salts with EDPBT. The in situ-generated isothiocyanates reacts with an aqueous ammonia, forming alkyl or aryl thioureas, which on subsequent oxidative desulfurization with EDPBT led to the formation of corresponding cyanamides in good yields. Alternatively, an efficient one-pot synthesis of substituted thiazoles has been achieved by the condensation of the in situ-generated 1-aryl thioureas with the in situ-generated -bromoketones from ketones, again using EDPBT. The reagent EDPBT can be easily prepared from the readily available reagents. Desulfurizing ability dominates over its brominating ability for substrates amenable to bromination.
- Yella, Ramesh,Kavala, Veerababurao,Patel, Bhisma K.
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experimental part
p. 792 - 805
(2011/04/22)
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- Tandem regioselective synthesis of tetrazoles and related heterocycles using iodine
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A one-pot, tandem process has been developed for the synthesis of a library of tetrazoles from aryl isothiocyanates. Condensation of aryl isothiocyanates with ammonia, and aryl amines (R-NH2) provided mono, 1,3-disubstituted symmetrical and unsymmetrical thioureas, which on desulfurization with molecular iodine (I2) led to formation of the corresponding heterocumulene (cyanamides or carbodiimides). The in situ generated heterocumulene on subsequent treatment with sodium azide at room temperature gave corresponding tetrazoles. The product regioselectivity for unsymmetrical 1,3-disubstituted thioureas was found to be correlated with the basicities (pKa's) of the parent amines attached to the thiourea. Aryl-sec-alkyl unsymmetrical thioureas gave thioamido guanidino products rather than the 5-aminotetrazoles produced by HgCl2 mediation of the reaction. Bis-thioureas derived from aryl isothiocyanates and hydrazine gave thiadiazoles exclusively.
- Yella, Ramesh,Khatun, Nilufa,Rout, Saroj Kumar,Patel, Bhisma K.
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experimental part
p. 3235 - 3245
(2011/06/20)
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- 4-Pyridylanilinothiazoles that selectively target von Hippel - Lindau deficient renal cell carcinoma cells by inducing autophagic cell death
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Renal cell carcinomas (RCC) are refractory to standard therapy with advanced RCC having a poor prognosis; consequently treatment of advanced RCC represents an unmet clinical need. The von Hippel-Lindau (VHL) tumor suppressor gene is mutated or inactivated in a majority of RCCs. We recently identified a 4-pyridyl-2-anilinothiazole (PAT) with selective cytotoxicity against VHL-deficient renal cells mediated by induction of autophagy and increased acidification of autolysosomes. We report exploration of structure-activity relationships (SAR) around this PAT lead. Analogues with substituents on each of the three rings, and various linkers between rings, were synthesized and tested in vitro using paired RCC4 cell lines. A contour map describing the relative spatial contributions of different chemical features to potency illustrates a region, adjacent to the pyridyl ring, with potential for further development. Examples probing this domain validated this approach and may provide the opportunity to develop this novel chemotype as a targeted approach to the treatment of RCC. 2009 American Chemical Society.
- Hay, Michael P.,Turcotte, Sandra,Flanagan, Jack U.,Bonnet, Muriel,Chan, Denise A.,Sutphin, Patrick D.,Nguyen, Phuong,Giaccia, Amato J.,Denny, William A.
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supporting information; experimental part
p. 787 - 797
(2010/07/05)
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- Synthesis, characterization and biological evaluation of some thiourea derivatives bearing benzothiazole moiety as potential antimicrobial and anticancer agents
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Five series of thiourea derivatives bearing benzothiazole moiety (20 compounds) were efficiently synthesized and evaluated for antimicrobial and anticancer activities. The results indicated that the compounds possessed a broad spectrum of activity against the tested microorganisms and showed higher activity against fungi than bacteria. Compounds 1b, 2b, 3b, 4b and 5b exhibited the greatest antimicrobial activity. Preliminary study of the structure-activity relationship revealed that electronic factors in benzothiazole rings had a great effect on the antimicrobial activity of these compounds. In preliminary MTT cytotoxicity studies, the thiourea derivatives (2d, 5c and 5d) were found most potent. In MCF-7 and HeLa cells, the IC50 values were observed in the range of 18-26?μM and 38-46?μM, respectively.
- Saeed, Sohail,Rashid, Naghmana,Jones, Peter G.,Ali, Muhammad,Hussain, Rizwan
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experimental part
p. 1323 - 1331
(2010/05/18)
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- An efficient synthesis of cyanamide from amine promoted by a hypervalent iodine(III) reagent
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In a one-pot strategy we have achieved an efficient method for the synthesis of organic cyanamides starting from dithiocarbamic acid salts/amines. In this strategy the in situ generated alkyl or aryl isothiocyanates, obtained by the desulfurization of dithiocarbamic acid salts with diacetoxyiodobenzene (DIB) react with aqueous ammonia forming alkyl or aryl thiourea which on subsequent oxidative desulfurization with DIB led to the formation of corresponding cyanamide in good yields. Mild reaction conditions, shorter reaction time, an environmentally benign protocol, and easy isolation of the desired product make the present methodology a suitable alternative for the preparation of various organic cyanamides.
- Ghosh, Harisadhan,Yella, Ramesh,Ali, Abdur Rezzak,Sahoo, Santosh K.,Patel, Bhisma K.
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experimental part
p. 2407 - 2410
(2009/07/26)
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- NOVEL BIFUNCTIONAL COMPOUNDS WHICH INHIBIT PROTEIN KINASES AND HISTONE DEACETYLASES
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The present invention relates to a bifunctional compound of formula I or its pharmaceutically acceptable salts or solvates A-L-B (I) wherein A is a histone deacetylase (HDAC) inhibitory moiety, L is a single bond or a linker group and B is a protein kinase inhibitory moiety. The bifunctional compound according to formula (I) is useful for the treatment of malignant and non-malignant neoplasia and diseases related to abnormal cell growth
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Page/Page column 82
(2009/06/27)
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- Design of chimeric histone deacetylase- and tyrosine kinase-inhibitors: A series of Imatinib hybrides as potent Inhibitors of wild-type and mutant BCR-ABL, PDGF-Rβ, and histone deacetylases
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Inhibitors of histone deacetylases are a new class of cancer therapeutics with possibly broad applicability. Combinations of HDAC inhibitors with the kinase inhibitor 1 (Imatinib) in recent studies showed additive and synergistic effects. Here we present a new concept by combining inhibition of protein kinases and HDACs, two independent pharmacological activities, in one synthetic small molecule. In general, the HDAC inhibition profile, the potencies, and the probable binding modes to HDAC1 and HDAC6 were similar as for 6 (SAHA). Inhibition of Abl kinase in biochemical assays was maintained for most compounds, but in general the kinase selectivity profile differed from that of 1 with nearly equipotent inhibition of the wildtype and the Imatinib resistant Abl T315I mutant. A potent cellular inhibition of PDGFR and cytotoxicity toward EOL-1 cells, a model for idiopathic hypereosinophilic syndrome (HES), are restored or enhanced for selected analogues (12b, 14b, and 18b). Cytotoxicity was evaluated by using a broad panel of tumor cell lines, with selected analogues displaying mean IC50 values between 3.6 and 7.1 μM.
- Mahboobi, Siavosh,Dove, Stefan,Sellmer, Andreas,Winkler, Matthias,Eichhorn, Emerich,Pongratz, Herwig,Ciossek, Thomas,Baer, Thomas,Maier, Thomas,Beckers, Thomas
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supporting information; experimental part
p. 2265 - 2279
(2009/12/31)
-
- HETEROARYL COMPOUNDS, COMPOSITIONS, AND METHODS OF USE IN CANCER TREATMENT
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Provided herein are novel heteroaryl compounds, compositions comprising the compounds, and methods of treatment or prevention comprising administration of the compounds. The compounds are effective in the targeting of cells defective in the von Hippel-Lindau gene and in inducing autophagic cell death. The methods are directed to treating or preventing diseases such as cancer, and in particular cancers resulting from von Hippel-Lindau disease. The compounds of the invention may be administered in combination with another therapeutic agent.
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Page/Page column 147
(2009/10/22)
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- A one-pot preparation of cyanamide from dithiocarbamate using molecular iodine
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An efficient one-pot method for the synthesis of cyanamides from dithiocarbamate salts via a double desulfurization strategy using molecular iodine is disclosed. Dithiocarbamates, by the action of iodine yield isothiocyanates in situ, which on treatment with aqueous NH3 give thioureas. The thioureas so generated undergo further oxidative desulfurization with I2 giving corresponding cyanamides in good yields. Environmental benignity, cost effectiveness and high yields are the important attributes of this one pot procedure. The Royal Society of Chemistry 2009.
- Nath, Jayashree,Patel, Bhisma K.,Jamir, Latonglila,Sinha, Upasana Bora,Satyanarayana
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experimental part
p. 1503 - 1506
(2010/05/18)
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- A library of novel allosteric inhibitors against fructose 1,6-bisphosphatase
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The identification of a proper lead compound for fructose 1,6-bisphosphatase (FBPase) is a critical step in the process of developing novel therapeutics against type-2 diabetes. Herein, we have successfully generated a library of allosteric inhibitors against FBPase as potential anti-diabetic drugs, of which, the lead compound 1b was identified through utilizing a virtual high-throughput screening (vHTS) system, which we have developed. The thiazole-based core structure was synthesized via the condensation of α-bromo-ketones with thioureas and substituents on the two aryl rings were varied. 4c was found to inhibit pig kidney FBPase approximately fivefold better than 1b. In addition, we have also identified 10b, a tight binding fragment, which can be use for fragment-based drug design purposes.
- Heng, Sabrina,Gryncel, Kimberly R.,Kantrowitz, Evan R.
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experimental part
p. 3916 - 3922
(2009/10/02)
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- Design, synthesis, cytoselective toxicity, structure-activity relationships, and pharmacophore of thiazolidinone derivatives targeting drug-resistant lung cancer cells
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Ten cytoselective compounds have been identified from 372 thiazolidinone analogues by applying iterative library approaches. These compounds selectively killed both non-small cell lung cancer cell line H460 and its paclitaxel-resistant variant H460taxR at an IC50 between 0.21 and 2.93 μM while showing much less toxicity to normal human fibroblasts at concentrations up to 195 μM. Structure-activity relationship studies revealed that (1) the nitrogen atom on the 4-thiazolidinone ring (ring B in Figure 1) cannot be substituted, (2) several substitutions on ring A are tolerated at various positions, and (3) the substitution on ring C is restricted to the -NMe2 group at the 4-position. A pharmacophore derived from active molecules suggested that two hydrogen bond acceptors and three hydrophobic regions were common features. Activities against P-gp-overexpressing and paclitaxel-resistant cell line H460taxR and modeling using a previously validated P-gp substrate pharmacophore suggested that active compounds were not likely P-gp substrates.
- Zhou, Hongyu,Wu, Shuhong,Zhai, Shumei,Liu, Aifeng,Sun, Ying,Li, Rongshi,Zhang, Ying,Ekins, Sean,Swaan, Peter W.,Fang, Bingliang,Zhang, Bin,Yan, Bing
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p. 1242 - 1251
(2008/12/23)
-
- Synthesis and antimicrobial evaluation of some novel 2-aminothiazole derivatives of 4-hydroxy-chromene-2-one
-
Syntheses of 2-aminothiazole derivatives of 4-hydroxy-chromene-2-one 2c-10c are reported in this paper. These compounds 2c-10c were prepared from 3-(2-bromoacetyl)-4-hydroxy-chromene-2-one 1 and corresponding thiourea derivatives 2b-10b using Hantzsch reaction. The structures of all compounds were confirmed by IR and 1H-NMR spectroscopy and elemental analyses. The molecules 2c-10c were evaluated for in vitro antimicrobial activity against ten bacteria and twelve fungi. All tested compounds exhibited antibacterial and antifungal activity.
- Vukovic, Nenad,Sukdolak, Slobodan,Solujic, Slavica,Milosevic, Tanja
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experimental part
p. 491 - 496
(2009/04/04)
-
- NITROGEN-CONTAINING FUSED HETEROCYCLIC COMPOUNDS
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There is provided a CRF receptor antagonist comprising a compound of the formula (I): wherein, ring A is a 5-membered ring represented by the formula (A'): wherein X is a carbon and X is an oxygen, a sulfur or - NR -,or formula (A"): wherein X is a nitrogen and R is an optionally substituted hydrocarbyl, Ris an amino substituted by two optionally substituted hydrocarbyl groups, Ris an phenyl, Y is CR or a nitrogen, Y is CRor a nitrogen and Yis CRor a nitrogen, provided that one or less of Y, Y, and Y is nitrogen, W is a bond, -(CH2)n-, and Z is a bond, -NR -,etc.; or a salt thereof or a prodrug thereof.
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Page/Page column 108
(2010/02/11)
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- Benzodiazepine derivatives
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Compounds of Formula (I), and salts and prodrugs thereof, wherein said formula, R 1 represents certain optionally substituted alkyl or C 3-7 cycloalkyl; R 2 represents (II) or (III), where m is 0, 1, 2 or 3; R 9 is H or C 1-6 alkyl; R 10 is imidazolyl, triazolyl or tetrazolyl, and R 11 is H, C 1-6 alkyl or halo; R 3 is C 1-6 alkyl, halo or NR 6 R 7 ; R 4 is C 1-7 alkyl, C 3-10 cycloalkyl, C 3-10 cycloalkylC 1-4 alkyl, C 6-10 bicycloalkyl, optionally substituted aryl, or NR 12 R 13 ; R 5 is H or C 1-4 alkyl; n is 0, 1, 2 or 3; which are CCK and/or gastrin antagonists useful in therapy.
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- Cyclic guanidines; IV. Intramolecular nucleophilic aromatic substitution of hydrogen in (3-nitrophenyl)guanidines
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Cyclization of substituted (3-nitrophenyl)guanidines is achieved in basic medium by nucleophilic displacement of hydrogen. The reaction offers a new route to benzimidazoles as well as to tricyclic imidazo-, pyrimido- and diazepino-benzimidazoles with unco
- Esser,Pook
-
p. 596 - 601
(2007/10/02)
-
- KINETICS AND MECHANISM OF METHANOLYSIS OF BENZOYL DERIVATIVES OF SUBSTITUTED PHENYLUREAS AND PHENYLTHIOUREAS
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The methanolysis rate constants and dissociation constants have been measured of benzoyl derivatives of substituted phenylureas and phenylthioureas.The dissociation constants of the thio derivatives are higher by 1 order of magnitude and the rate constants are higher by 2 orders of magnitude than the respective values of the oxygen analogues.Logarithms of the rate and dissociation constants have been correlated with Hammett ? constant; the ρ constant of the methanolysis of the oxygen derivatives is almost 2 * higher than that of the thio derivatives, which is explained by a change in the rate-limiting step.Methylation of the phenyl nitrogen atom increases the acidity by almost 2 orders of magnitude.This effect is due obviously to steric hindrance to the conjugation with the adjacent carbonyl or thiocarbonyl group.
- Kavalek, Jaromir,El Bahaie, Said,Sterba, Vojeslav
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p. 2103 - 2110
(2007/10/02)
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