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Urea Derivatives (urea + derivative)
Selected AbstractsThree New Urea Derivatives from Pliocene-Fossil Pinus armandiiHELVETICA CHIMICA ACTA, Issue 2 2005You-Xing Zhao Three new urea derivatives, isolated from the Pliocene lignified wood of Pinus armandii, were identified as carbonylbis[imino(6-methyl-3,1-phenylene)]bis[carbamic acid] dimethyl ester (1), and as the corresponding dibutyl ester 2 and bis(2-methylpropyl) ester 3. Their structures were elucidated by spectroscopic methods, including MS and 1D- and 2D-NMR techniques. [source] ChemInform Abstract: Synthesis of Urea Derivatives from CO2 and Amines Catalyzed by Polyethylene Glycol Supported Potassium Hydroxide Without Dehydrating Agents.CHEMINFORM, Issue 36 2010De-Lin Kong Abstract A simple catalyst is developed and efficiently used for the fixation of carbon dioxide as symmetrical urea derivatives. [source] ChemInform Abstract: Urea Derivatives Are Highly Active Catalysts for the Base-Mediated Generation of Terminal Epoxides from Aldehydes and Trimethylsulfonium Iodide.CHEMINFORM, Issue 33 2008Sarah A. Kavanagh Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Microwave Promoted Solvent-Free One-Pot Synthesis of N,N,-Disubstituted Urea Derivatives.CHEMINFORM, Issue 37 2005Vinod H. Jadhav Abstract For Abstract see ChemInform Abstract in Full Text. [source] Regioselective and Enantioselective Synthesis of Seven-Membered Ring Cyclic Arylguanidine and Urea Derivatives.CHEMINFORM, Issue 20 2004Hai-Bing Zhou Abstract For Abstract see ChemInform Abstract in Full Text. [source] Urea derivatives on the move: cytokinin-like activity and adventitious rooting enhancement depend on chemical structurePLANT BIOLOGY, Issue 3 2009A. Ricci Abstract Urea derivatives are synthetic compounds, some of which have proved to be positive regulators of cell division and differentiation. N -phenyl- N,-(2-chloro-4-pyridyl)urea (forchlorofenuron, CPPU) and N -phenyl- N,-(1,2,3-thiadiazol-5-yl)urea (thidiazuron, TDZ), well known urea cytokinin representatives, are extensively used in in vitro plant morphogenesis studies, as they show cytokinin-like activity often exceeding that of adenine compounds. In recent years, renewed interest in structure,activity relationship studies allowed identification of new urea cytokinins and other urea derivatives that specifically enhance adventitious root formation. In this review, we report the research history of urea derivatives, new insights into their biological activity, and recent progress on their mode of action. [source] ChemInform Abstract: Design, Synthesis, and in vitro Antitumor Evaluation of Novel Diaryl Ureas Derivatives.CHEMINFORM, Issue 40 2010Min Sun Abstract Two series of diaryl ureas are synthesized and their antitumor effect against human non-small cell lung cancer cell line and breast cancer line is investigated. [source] Organocatalysis Mediated by (Thio)urea DerivativesCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2006Stephen J. Connon Dr. Abstract Over the last decade the potential for N,N -dialkyl(thio)urea derivatives to serve as active metal-free organocatalysts for a wide range of synthetically useful reactions susceptible to the influence of general acid catalysis has begun to be realised. This article charts the development of these catalysts (with emphasis on the design principles involved), from early "proof-of-concept" materials to contemporary active chiral (bifunctional) promoters of highly selective asymmetric transformations. [source] Discrepancy between acute and chronic toxicity induced by imidacloprid and its metabolites in Apis melliferaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2001Séverine Suchail Abstract Imidaclopridi a systemic nitroguanidine insecticide that belongs to theneonicotinoid family. As an agonist of the acetylcholine receptor, it attacks the insect nervous system and is extremely effective against various sucking and mining pests. Oral acute and chronic toxicity of imidacloprid and its main metabolites (5-hydroxyimidacloprid, 4,5-dihydroxyimidacloprid, desnitroimidacloprid, 6-chloronicotinic acid, olefin, and urea derivative) were investigated in Apis mellifera. Acute intoxication by imidacloprid or its metabolites resulted in the rapid appearance of neurotoxicity symptoms, such as hyperresponsiveness, hyperactivity, and trembling and led to hyporesponsiveness and hypoactivity. For acute toxicity tests, bees were treated with doses of toxic compounds ranging from 1 to 1,000 ng/bee (10,10,000 ,g/kg). Acute toxicity (LD50) values of imidacloprid were about 60 ng/bee (600 ,g/kg) at 48 h and about 40 ng/bee (400 ,g/kg) at 72 and 96 h. Out of the six imidacloprid metabolites tested, only two (5-hydroxyimidacloprid and olefin) exhibited a toxicity close to that of imidacloprid. Olefin LD50 values were lower than those of imidacloprid. The 5-hydroxyimidacloprid showed a lower toxicity than imidacloprid with a LD50 four to six times higher than that of imidacloprid. Urea also appeared as a compound of nonnegligible toxicity by eliciting close to 40% mortality at 1,000 ng/bee (10,000 ,g/kg). However, no significant toxicity was observed with 4,5-dihydroxyimidacloprid, 6-chloronicotinic acid, and desnitroimidacloprid in the range of doses tested. To test chronic toxicity, worker bees were fed sucrose solutions containing 0.1, 1, and 10 ,g/L of imidacloprid and its metabolites for 10 d. Fifty percent mortality was reached at approximately 8 d. Hence, considering that sucrose syrup was consumed at the mean rate of 12 ,l/d and per bee, after an 8-d period the cumulated doses were approximately 0.01, 0.1, and 1 ng/bee (0.1, 1, and 10 ,g/kg). Thus, all tested compounds were toxic at doses 30 to 3,000 (olefin), 60 to 6,000 (imidacloprid), 200 to 20,000 (5-OH-imidacloprid), and >1,000 to 100,000 (remaining metabolites) times lower than those required to produce the same effect in acute intoxication studies. For all products tested, bee mortality was induced only 72 h after the onset of intoxication. [source] 4-[18F]fluorophenyl ureas via carbamate-4-nitrophenyl esters and 4-[18F]fluoroaniline,JOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 12 2006Sebastian Olma Abstract Four different no carrier added (n.c.a.) 4-[18F]fluorophenylurea derivatives are synthesized as model compounds via two alternative routes. In both cases carbamate-4-nitrophenylesters are used as intermediates. Either n.c.a. 4-[18F]fluoroaniline reacts with carbamates of several amines, or the carbamate of n.c.a. 4-[18F]fluoroaniline is formed at first and an amine is added subsequently to yield the urea derivative. The choice of the appropriate way of reaction depends on the possibilities of precursor synthesis. The radiochemical yields reach up to 80% after 50 min of synthesis time while no radiochemical by-products can be determined. These high yields were possible due to an optimized preparation of n.c.a. 4-[18F]fluoroaniline with a radiochemical yield of up to 90%. From the various ways of its radiosynthesis, the substitution with n.c.a. [18F]fluoride on dinitrobenzene is chosen, using phosphorous acid and palladium black for reduction of the second nitro group. Copyright © 2006 John Wiley & Sons, Ltd. [source] Three New Urea Derivatives from Pliocene-Fossil Pinus armandiiHELVETICA CHIMICA ACTA, Issue 2 2005You-Xing Zhao Three new urea derivatives, isolated from the Pliocene lignified wood of Pinus armandii, were identified as carbonylbis[imino(6-methyl-3,1-phenylene)]bis[carbamic acid] dimethyl ester (1), and as the corresponding dibutyl ester 2 and bis(2-methylpropyl) ester 3. Their structures were elucidated by spectroscopic methods, including MS and 1D- and 2D-NMR techniques. [source] Synthesis, structure, and biological activity of novel 4,5-disubstituted thiazolyl urea derivativesHETEROATOM CHEMISTRY, Issue 1 2008Shao Ling Novel 1-(2,4-dichlorophenyl)-3-[4-aryl-5-(1H -1,2,4-triazol-1-yl)thiazol-2-yl] urea derivatives were synthesized by the reaction of 2-amino-4-sustituted phentyl-5-(1H -1,2,4-triazol-1-yl) thiazoles with 2,4-dichloro-1-isocyanatobenzene. Structures of the title compounds were confirmed by the elemental analysis, 1H NMR, and single crystal X-ray diffraction analysis. Biological evaluation showed that some of them possess promising antitumor activities. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:2,6, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20375 [source] Experimental and theoretical studies on some new pyrrol-2,3-diones formationHETEROATOM CHEMISTRY, Issue 1 2004Ismail Yildirim 4-Benzoyl-5-phenyl-2,3-furandione (1) reacts with asymmetric disubstituted urea derivatives like 1,1-dimethylurea (2a) and 1,1-diethylurea (2b) by the elimination of a H2O molecule to give the 4-benzoyl-1-(N,N -dialkylcarbamyl)-5-phenyl-2,3-pyrroldiones 3a and 3b. The structures of 3a,b were determined by the 13C NMR, 1H NMR, IR spectroscopic data and elemental analyses. The electronic structures of the reactants, their transition states, intermediate states, and final products of the reactions were investigated on the basis of AM1 and ab initio (DFT) methods. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 15:9,14, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10204 [source] Correlation between the predicted and the observed biological activity of the symmetric and nonsymmetric cyclic urea derivatives used as HIV-1 protease inhibitors.JOURNAL OF CELLULAR AND MOLECULAR MEDICINE, Issue 3 2003A 3D-QSAR-CoMFA method for new antiviral drug design Abstract The predicted inhibition constant (Ki) and the predicted inhibitor concentration (IC90) of the HIV-1 protease (HIV-1 PR) inhibitors: symmetric and nonsymmetric - benzyl, ketone, oxime, pyrazole, imidazole, and triazole cyclic urea derivatives, were obtained by the 3D-CoMFA (Comparative Molecular Field Analysis) method. The CoMFA statistical parameters: cross-validate correlation coefficient (q2), higher than 0.5, and the fitted correlation coefficient (r2), higher than 0.90 validated the predicted biological activities. The best predictions were found for the trifluoromethyl ketoxime derivative (log 1/Ki predict = 8.42), the m-pyridineCH2 pyrazole derivative (log 1/Ki predict = 9.77) and the 1,2,3 triazole derivative (log 1/Ki predict = 7.03). We attempted to design a new potent HIV-1 protease inhibitor by addition of o-benzyl to the (p-HOPhCH2) pyrazole 12f derivative inhibitor. A favorable steric area surrounded the o-benzyl, suggesting a possible new potent HIV-1 protease inhibitor. [source] Ethyl-3,4-diaroyl-2-cyanobutyrate: A Synthon for novel heterocyclesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2009Adivireddy Padmaja A new class of aminopyrazolones, aminoisoxazolones, aminopyrimidinones, and thioxopyrimidinones were synthesized from Michael adduct, ethyl-3,4-diaroyl-2-cyanobutyrate, on reaction with different nucleophiles, hydrazine hydrate, hydroxylamine hydrochloride, and urea derivatives. J. Heterocyclic Chem., (2009). [source] One-pot synthesis of [11C]ureas via triphenylphosphiniminesJOURNAL OF LABELLED COMPOUNDS AND RADIOPHARMACEUTICALS, Issue 4 2006Erica W. van Tilburg Abstract A series of 11C-labeled ureas was prepared using a rapid and efficient one-pot procedure. First, the intermediate [11C]phenylisocyanate was formed with phenyltriphenylphosphinimine and [11C]CO2. A range of amines was then reacted with the [11C]phenylisocyanate yielding the [11C]urea derivatives in short synthesis times. This easy-to-handle method circumvents disadvantages of known procedures and generates the possibility to prepare other kinds of 11C-labeled compounds using a variety of phenylphosphinimines in combination with different nucleophiles. The presented approach is an alternative to the use of established methods in 11C-labeling chemistry. Copyright © 2006 John Wiley & Sons, Ltd. [source] Influence of steric hindrance on enantioseparation of Dns-amino acids and pesticides on terguride based chiral selectors in capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 7 2005Honzátko Abstract Three urea derivatives of ergoline-based chiral selectors (CSs), differing in the size of the urea side chain, i. e. dimethyl- (CSI), diethyl- (CSII), and diisopropylurea (CSIII), were used to study the effect of steric hindrance on the enantioseparation of dansyl amino acids (Dns-AAs), pesticides, and mandelic acid under condition of capillary electrophoresis (CE) in linear polyacrylamide coated capillaries. A mixture of organic modifiers (MeOH/THF, 4 : 1 v/v) in a BGE consisting of 100 mM ,-alanine-acetate was used to increase the solubility of CSs up to 25 mM. The capillary was filled with CS (high UV absorption), and the inlet and outlet vials contained buffer solutions only. The best enantioseparation of Dns-AAs was achieved on CSI. Increased steric hindrance of the chiral binding site led to reduction of both enantioselectivity and resolution. The opposite pattern was observed for the separation of mandelic acid enantiomers, where the best enantioseparation and resolution was obtained with CSIII. Most of the pesticides studied reached maximum selectivity on the diethylurea ergoline derivative (CSII). Enantioseparation of fenoxaprop was found to be independent of steric hindrance. [source] In vivo distribution and metabolisation of 14C-imidacloprid in different compartments of Apis mellifera LPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2004Séverine Suchail Abstract In vivo distribution of the neonicotinoid insecticide, imidacloprid, was followed during 72 h in six biological compartments of Apis mellifera L: head, thorax, abdomen, haemolymph, midgut and rectum. Honeybees were treated orally with 100 µg of 14C-imidacloprid per kg of bee, a dose close to the median lethal dose. Elimination half-life of total radioactivity in honeybee was 25 h. Haemolymph was the compartment with the lowest and rectum that with the highest level of total radioactivity during the whole study, with a maximum 24 h after treatment. Elimination half-life of imidacloprid in whole honeybee was 5 h. Imidacloprid was readily distributed and metabolised only by Phase I enzymes into five metabolites: 4/5-hydroxy-imidacloprid, 4,5-dihydroxy-imidacloprid, 6-chloronicotinic acid, and olefin and urea derivatives. The guanidine derivative was not detected. The urea derivative and 6-chloronicotinic acid were the main metabolites and appeared particularly in midgut and rectum. The olefin derivative and 4/5-hydroxy-imidacloprid preferentially occurred in head, thorax and abdomen, which are nicotinic acetylcholine receptor-rich tissues. Moreover, they presented a peak value around 4 h after imidacloprid ingestion. These results explain the prolongation of imidacloprid action in bees, and particularly the differences between rapid intoxication symptoms and late mortality. Copyright © 2004 Society of Chemical Industry [source] Urea derivatives on the move: cytokinin-like activity and adventitious rooting enhancement depend on chemical structurePLANT BIOLOGY, Issue 3 2009A. Ricci Abstract Urea derivatives are synthetic compounds, some of which have proved to be positive regulators of cell division and differentiation. N -phenyl- N,-(2-chloro-4-pyridyl)urea (forchlorofenuron, CPPU) and N -phenyl- N,-(1,2,3-thiadiazol-5-yl)urea (thidiazuron, TDZ), well known urea cytokinin representatives, are extensively used in in vitro plant morphogenesis studies, as they show cytokinin-like activity often exceeding that of adenine compounds. In recent years, renewed interest in structure,activity relationship studies allowed identification of new urea cytokinins and other urea derivatives that specifically enhance adventitious root formation. In this review, we report the research history of urea derivatives, new insights into their biological activity, and recent progress on their mode of action. [source] Synthesis and Antiproliferative Activitiy of Novel Diaryl Ureas Possessing a 4H- Pyrido[1,2- a]pyrimidin-4-one GroupARCHIV DER PHARMAZIE, Issue 1 2010Peng Yao Abstract We herein disclose a series of novel diaryl urea derivatives possessing a 4H- pyrido[1,2 -a]pyrimidin-4-one group as novel potent anticancer compounds. The structures were confirmed by IR, 1H-NMR, and MS. All the compounds were screened for their antiprofilerative activity agaist the human breast cancer cell line (MDA-MB-231). The pharmacological results indicated that most of the compounds showed moderate activity. The best of this series is compound 4c (IC50 = 0.7 ,mol/L), with a potency 3.6-fold higher than Sorafenib (IC50 = 2.5 ,mol/L), which was approved in 2005. [source] ChemInform Abstract: Synthesis of Urea Derivatives from CO2 and Amines Catalyzed by Polyethylene Glycol Supported Potassium Hydroxide Without Dehydrating Agents.CHEMINFORM, Issue 36 2010De-Lin Kong Abstract A simple catalyst is developed and efficiently used for the fixation of carbon dioxide as symmetrical urea derivatives. [source] Organocatalysis Mediated by (Thio)urea DerivativesCHEMISTRY - A EUROPEAN JOURNAL, Issue 21 2006Stephen J. Connon Dr. Abstract Over the last decade the potential for N,N -dialkyl(thio)urea derivatives to serve as active metal-free organocatalysts for a wide range of synthetically useful reactions susceptible to the influence of general acid catalysis has begun to be realised. This article charts the development of these catalysts (with emphasis on the design principles involved), from early "proof-of-concept" materials to contemporary active chiral (bifunctional) promoters of highly selective asymmetric transformations. [source] Non-racemic atropisomeric (thio)ureas as neutral enantioselective anion receptors for amino-acid derivatives: Origin of smaller Kass with thiourea than urea derivativesCHIRALITY, Issue 9 2006Christian Roussel Abstract The synthesis of a limited series of non-racemic atropisomeric 1-(2-(4-methyl-2-thioxothiazol-3(2H)-yl)phenyl)-3-(hetero)aryl-(thio)ureas is described. Using NMR titration experiments monitoring the shift of the two NH of the (thio)urea and the C-5 hydrogen of the heterocycle, the binding constants for some optically pure (thio)-ureas with the enantiomers of N-protected amino acid tetrabutylammonium salts were determined in CD3CN. The obtained enantioselectivities were modest. Contrary to what was expected on the basis of the NH acidity in thiourea versus urea group, the association constants were smaller with the thiourea than with the corresponding urea. X-ray data, DFT calculations, and NMR provided the explanation of that unexpected behavior: the urea presents a pre-organized (Z,Z) conformation suitable for a double hydrogen bond with the carboxylate anion, the thiourea presents a (Z,E) conformation, which must be reorganized in a constrained (Z,Z) conformation in the complex. An intramolecular hydrogen bond between one NH and the thiocarbonyl group of the heterocycle, which is present in the thiourea and absent in the urea, might also contribute to the smaller Kass for the thiourea. The possible implication of these observations in the field of bifunctional organocatalysis is briefly discussed. Chirality, 2006. © 2006 Wiley-Liss, Inc. [source] | |||||||||||||||||||||||||