- Urea-Catalyzed Vinyl Carbocation Formation Enables Mild Functionalization of Unactivated C-H Bonds
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Herein we report the 3,5-bistrifluoromethylphenyl urea-catalyzed functionalization of unactivated C-H bonds. In this system, the urea catalyst mediates the formation of high-energy vinyl carbocations that undergo facile C-H insertion and Friedel-Crafts re
- Bagdasarian, Alex L.,Popov, Stasik,Wigman, Benjamin,Wei, Wenjing,Lee, Woojin,Nelson, Hosea M.
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supporting information
p. 7775 - 7779
(2020/07/15)
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- Synthesis of Urea Derivatives from CO2 and Silylamines
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A series of thirty-three N,N′-diaryl, dialkyl, and alkyl-aryl ureas have been prepared in pyridine or toluene by reaction of silylamines with CO2. This protocol is shown to provide facile access to 13C-labeled ureas, as well as chiral and macrocyclic ureas. These reactions proceed through initial generation of the corresponding silylcarbamates, which subsequently react with silylamine under thermal conditions to afford the thermodynamically favored urea and disilyl ether.
- Xu, Maotong,Jupp, Andrew R.,Ong, Maegan S. E.,Burton, Katherine I.,Chitnis, Saurabh S.,Stephan, Douglas W.
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supporting information
p. 5707 - 5711
(2019/04/16)
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- Stoichiometric Reactions of CO2 and Indium-Silylamides and Catalytic Synthesis of Ureas
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The indium compounds In(N(SiMe3)2)2Cl?THF (2) and In(N(SiMe3)2)Cl2?(THF)n (3) were shown to react with CO2 to give [(Me3Si)2N)InX(μ-OSiMe3)]2 (X=N(SiMe3)2 4, Cl 5). 0.05–2.0 mol % of the species 3 acts as a pre-catalyst for the conversion of aryl and alkyl silylamines under CO2 (2–3 atm) to give the corresponding ureas in 70–99 % yields. A proposed mechanism is supported by experimental and computational data.
- Xu, Maotong,Jupp, Andrew R.,Stephan, Douglas W.
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p. 14277 - 14281
(2017/10/31)
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- An efficient one-pot synthesis of: N, N ′-disubstituted ureas and carbamates from N -acylbenzotriazoles
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A facile and high-yielding one-pot synthesis of carbamates and N,N′-disubstituted symmetrical ureas from N-acylbenzotriazoles has been devised. It is believed that, the intermediate acyl-azide undergo Curtius rearrangement and in different solvents gives different products i.e. carbamates in alcohols and N,N′-disubstituted symmetrical urea in THF.
- Singh, Anoop S.,Kumar, Dhananjay,Mishra, Nidhi,Tiwari, Vinod K.
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p. 84512 - 84522
(2016/10/12)
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- Palladium-catalyzed synthesis of symmetrical urea derivatives by oxidative carbonylation of primary amines in carbon dioxide medium
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An efficient palladium-catalyzed synthesis of symmetrically disubstituted ureas via oxidative carbonylation of primary amines is described. The reactions are carried out in the presence of a large excess of carbon dioxide as reaction medium or under solvent-free conditions. The adopted catalyst such as potassium tetraiodopalladate, stable and easy to prepare, allows the use of air as a cheap oxidizing agent. The reactions yield urea and water as the only by-product and proceed with high efficiency with aliphatic and aromatic amines as well. While with primary aliphatic amines, no significant improvement on reactivity is observed when carbon dioxide is used as a solvent, in comparison with the conventional ones, a remarkable high efficiency is obtained with aromatic amines, which shows a dramatic increase in the performance of the catalyst, in terms of turnover number (TON), the highest known so far for this kind of process. Reactions take place in two-phase systems consisting of a homogeneous liquid phase formed by the CO2 expanded amine solution containing the catalyst and a supercritical phase of CO2, CO, O2, and N2.
- Ca', Nicola Della,Bottarelli, Paolo,Dibenedetto, Angela,Aresta, Michele,Gabriele, Bartolo,Salerno, Giuseppe,Costa, Mirco
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experimental part
p. 120 - 127
(2011/09/16)
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- Selenium-catalyzed carbonylation of nitroarenes to symmetrical 1,3-diarylureas under atmospheric pressure
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Selenium-catalyzed carbonylation of nitrobenzene and substituted nitroarenes with CO under atmospheric pressure afforded symmetrical 1,3-diarylureas in yields up to 94%. A mechanism has been proposed to demonstrate the formation of symmetrical ureas.
- Wang, Xiaofang,Lu, Shiwei,Yu, Zhengkun
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p. 929 - 932
(2007/10/03)
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- Copper catalyzed arylation of urea
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An efficient copper catalyzed amidation of aryl iodides with urea is described. This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.
- Nandakumar, Mecheril V.
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p. 1989 - 1990
(2007/10/03)
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- Phosphate transport inhibitors
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Disclosed are compounds which have been identified as inhibitors of phosphate transport. Many of the compounds are represented by Structural Formula (I): Ar1—W—X—Y—Ar2; or a pharmaceutically acceptable salt thereof. Ar1 and Ar2 are independently a substituted or unsubstituted aryl group or an optionally substituted five membered or six membered non-aromatic heterocylic group fused to an optionally substituted monocylic aryl group. W and Y are independently a covalent bond or a C1-C3 substituted or unsubstituted alkylene group. X is a heteroatom-containing functional group, an aromatic heterocyclic group, substituted aromatic heterocyclic group, non-aromatic heterocyclic group, substituted non-aromatic heterocyclic group, an olefin group or a substituted olefin group. Also disclosed are methods of treating a subject with a disease associated with hyperphosphatemia, as well as a disease mediated by phosphate-transport function. The methods comprise the step of administering an effective amount of the one of the compounds described above.
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- Some structural changes on triazolyl-benzotriazoles and triazolyl-benzimidazolones as potential potassium channel activators. III
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This paper reports the synthesis and pharmacological evaluation of some compounds, obtained by structural modifications of 1,2,3-triazolyl-benzotriazoles and 1,2,3-triazolyl-benzimidazolones, which had shown activity as potential activators of the big-con
- Biagi, Giuliana,Calderone, Vincenzo,Giorgi, Irene,Livi, Oreste,Scartoni, Valerio,Baragatti, Barbara,Martinotti, Enrica
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p. 841 - 849
(2007/10/03)
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- REACTION OF AMINES WITH N-ARYLUREAS, ALKYL N-ARYLCARBAMATES, AND SALTS OF THIOCARBAMIC ACIDS
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The reaction of amines with N-arylureas, alkyl N-arylcarbamates, and salts of thiocarbamic acids is studied. The regularities found are explained by the characteristic features of hydrogen bond formation.
- Manov-Yuvenskii, V. I.,Kuznetsov, S. L.
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p. 1063 - 1069
(2007/10/02)
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- USE OF ISOCYANIC ACID FOR THE PREPARATION OF SUBSTITUTED UREAS
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A thermogravimetric study was carried out on the thermolysis of cyanuric acid and conditions were found for carrying out this reaction to give gaseous isocyanic acid.Dosing this acid in the vapor of inert organic solvents gave systems used for the selective synthesis of monosubstituted ureas.The reaction of gaseous isocyanic acid with amine vapor selectively gave highly pure N-cyclohexylurea and N,N'-bis(3-trifluoromethylphenyl)urea.
- Kirpichev, V. P.,Karachinskii, S. V.,Dragalov, V. V.,Peshkova, O. Yu.
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p. 1651 - 1653
(2007/10/02)
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- RELATIONSHIPS OF TRANSAMINATION OF SUBSTITUTED UREAS. V. THERMODYNAMICS OF TRANSAMINATION OF DIARYLUREAS BY DIALKYLAMINES
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The equilibrium constant of the transamination of N,N'-diarylureas by dialkylamines in o-dichlorobenzene in the range of 120-158 deg C depends significantly on the nature of both reagents.The enthalpy of activation and the entropy of dissociation of diarylureas are proportional to the thermal effect of the transamination of these ureas by diisobutylamine.The same relationships is observed between the enthalpy of activation of the bimolecular reaction of N,N'-diphenylurea with dialkylamines and the enthalpy of the process.The established relationships between the enthalpies of activation and the enthalpy of equilibrium are explained satisfactorily in terms of the Hammond-Thornton model.
- Chimishkyan, A. L.,Gulyaev, N. D.,Leonova, T. V.
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- THERMAL DECOMPOSITION OF SUBSTITUTED UREAS
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The thermal dissociation of N,N'-diaryl- and N,N-dimethyl-N'-aryl-ureas was investigated under isothermal conditions in absence of solvent.In the case of N,N-dimethyl-N'-arylureas enthalpies of reaction were determined, and their relation to Hammett ? constants was shown.
- Chimishkyan, A. L.,Svetlova, L. P.,Leonova, T. V.,Gluyaev, N. D.
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p. 1317 - 1320
(2007/10/02)
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- SUBSTITUENT EFFECTS ON HYDROLYTIC STABILITY AND HERBICIDAL ACTIVITY OF 3-ARYLIMIDAZOLIDINE-2,4-DIONES
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Twenty-one derivatives of imidazolidine-2,4-dione have been prepared by reactions of substituted amino acids with aryl isocyanates in aqueous medium.Pre- and post-emergent herbicidal activities of all the compounds have been tested, and stability of five derivatives has been followed in aqueous medium within the pH range from 7.6 to 13.0.The highest pre-emergent herbicidal activity has been found with the derivatives XI-XVI which inhibit the growth of most indicator plants at the doses of 1.6 kg/ha.The derivatives studied are relatively stable in aqueous medium, the hydrolysis half-life of the compound XI being 9 days at pH 8.
- Cegan, Alexandr,Vecera, Miroslav
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p. 1521 - 1528
(2007/10/02)
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- Investigations of the Products of Isocyanates with Hydroxylamine
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The reactions of isocyanates with hydroxylamine give rise to several compounds according to the different conditions involved when starting with the primary reaction products, the hydroxy-ureas.The pure compounds have been isolated.An interesting reaction of N-phenyl-N'-phenylcarbamoyloxyurea with sodium hydroxide has been observed.This compound is converted to 3-hydroxy-1,5-diphenylbiuret under conditions described.
- Becker, Alfred,Heizler, Werner
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p. 1011 - 1017
(2007/10/02)
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