- Solid-phase synthesis of 2-methoxyaniline derivatives by the traceless silicon linker strategy
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Application of the silicon linkage strategy to the solid-phase synthesis of the rich-electron o-anisidine derivatives is described. The protective t-Boc group was easily removed with B-catechol borane and the isocyanate was successfully prepared with the mild reagent (t-Boc)2O/DMAP. Carbamates, ureas or amides were prepared and released by cleavage with TFA at room temperature. This method can be used to prepare small focused libraries with biological activity at serotonin receptors.
- Curtet, Sophie,Langlois, Michel
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- Photodecomposition of Pigment Yellow 74, a pigment used in tattoo inks
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Tattooing has become a popular recreational practice among younger adults over the past decade. Although some of the pigments used in tattooing have been described, very little is known concerning the toxicology, phototoxicology or photochemistry of these pigments. Seven yellow tattoo inks were obtained from commercial sources and their pigments extracted, identified and quantitatively analyzed. The mono- azo compound Pigment Yellow 74 (PY74; CI 11741) was found to be the major pigment in several of the tattoo inks. Solutions of commercial PY74 in tetrahydrofuran (THF) were deoxygenated using argon gas, and the photochemical reaction products were determined after exposure to simulated solar light generated by a filtered 6.5 kW xenon arc lamp. Spectrophotometric and high-pressure liquid chromatography (HPLC) analyses indicated that PY74 photodecomposed to multiple products that were isolated using a combination of silica chromatography and reversed-phase HPLC. Three of the major photodecomposition products were identified by nuclear magnetic resonance and mass spectrometry as N-(2-methoxyphenyl)-3-oxobutanamide (o-acetoacetanisidide), 2-(hydroxyimine)-N-(2-methoxyphenyl)-3-oxobutanamide and N,N″-bis(2- methoxyphenyl)urea. These results demonstrate that PY74 is not photostable in THF and that photochemical lysis occurs at several sites in PY74 including the hydrazone and amide groups. The data also suggest that the use of PY74 in tattoo inks could potentially result in the formation of photolysis products, resulting in toxicity at the tattoo site after irradiation with sunlight or more intense light sources.
- Cui, Yanyan,Spann, Andrew P.,Couch, Letha H.,Gopee, Neera V.,Evans, Frederick E.,Churchwell, Mona I.,Williams, Lee D.,Doerge, Daniel R.,Howard, Paul C.
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- Depalladation of neutral monoalkyne- and dialkyne-inserted palladacycles and alkyne insertion/depalladation reactions of cationic palladacycles derived from N, N ′, N ″-triarylguanidines as facile routes for guanidine-containing heterocycles/carbocycles: Synthetic, structural, and mechanistic aspects
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Depalladation of the monoalkyne-inserted cyclopalladated guanidines [κ2(C,N)Pd(2,6-Me2C5H3N)Br] (I and II) in PhCl under reflux conditions and that of the dialkyne-inserted cyclopalladated guanidine [κ2(C,N):n2(C=C)PdBr] (III) in pyridine under reflux conditions afforded a guanidine-containing indole (1), imidazoindole (2), and benzazepine (3) in 80%, 67%, and 76%, yields, respectively. trans-[L2PdBr2] species (L = 2,6-Me2C5H3N, C5H5N) were also isolated in the aforementioned reactions in 35%, 42%, and 40% yields. Further, the reaction of the cyclopalladated guanidine [κ2(C,N)Pd(μ-Br)]2 (IV) with AgBF4 in a CH2Cl2/MeCN mixture afforded the cationic pincer type cyclopalladated guanidine [κ3(C,N,O)Pd(MeCN)][BF4] (4) in 85% yield and this palladacycle upon crystallization in MeCN and the reaction of [κ2(C,N)Pd(μ-Br)]2 (V) with AgBF4 in a CH2Cl2/MeCN mixture afforded the cationic palladacycles [{κ2(C,N)Pd(MeCN)2][BF4] (5 and 6) in 89% and 91% yields, respectively. The separate reactions of 4 with 2 equiv of methyl phenylpropiolate (MPP) or diphenylacetylene (DPA) and the reaction of 5 with 2 equiv of MPP in PhCl at 110 °C afforded the guanidine-containing quinazolinium tetrafluoroborate 7 in 25-32% yields. The reaction of 6 with 2 equiv of DPA under otherwise identical conditions afforded the unsymmetrically substituted guanidinium tetrafluoroborate 8, containing a highly substituted naphthalene unit, in 82% yield. Compounds 1-8 were characterized by analytical and spectroscopic techniques, and all compounds except 4 were characterized by single-crystal X-ray diffraction. The molecular structures of 2 and 3 are novel, as the framework in the former arises due to the formation of two C-N bonds upon depalladation while the butadienyl unit in the latter revealed cis,cis stereochemistry, a feature unprecedented in alkyne insertion chemistry. Plausible pathways for the formation of heterocycles/carbocycles are proposed. The influence of substituents on the aryl rings of the cyclopalladated guanidine moiety and those on alkynes upon the nature of the products is addressed. Heterocycles 1 and 7 revealed the presence of two rotamers in about a 1.00:0.43 ratio in CDCl3 and in about a 1.00:0.14 ratio in CD3OD, respectively, as detected by 1H NMR spectroscopy while in CD3CN and DMSO-d6 (1) and CD3CN and CDCl3 (7), these heterocycles revealed the presence of a single rotamer. These spectral features are attributed to the restricted C-N single-bond rotation of the CN3 unit of the guanidine moiety, which possibly arises from steric constraint due to the formation of a N-H···Cl hydrogen bond with CDCl3 (1) and N-H···O and O-D···O hydrogen bonds with CD3OD (7).
- Saxena, Priya,Thirupathi, Natesan,Nethaji, Munirathinam
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- Method for photocatalytic synthesis of substituted urea compound
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The invention relates to the technical field of organic synthesis, in particular to a method for photocatalytic synthesis of a substituted urea compound. The method specifically comprises the following steps: mixing tetrahalomethane and a solvent, then adding an amine compound and a catalyst in sequence, stirring and reacting under an oxygen-containing atmosphere and an illumination condition, and then separating and purifying to obtain the substituted urea compound, according to the synthesis method, the raw materials are wide in source, by-products produced after the reaction are halogen simple substances and high in additional value, on one hand, phosgene, triphosgene and the like which are high in toxicity are prevented from being adopted as raw materials, on the other hand, generation of a large amount of waste is avoided, the catalyst can be recycled, the influence of the preparation process on the environment is reduced, and the atom utilization rate of the reaction is improved.
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Paragraph 0051-0052; 0057
(2021/06/09)
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- An Improved Synthesis of Urea Derivatives from N -Acylbenzotriazole via Curtius Rearrangement
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The good leaving tendency of the benzotriazole moiety has been exploited for the synthesis of symmetric, unsymmetric, N -acyl, and cyclic ureas in good yields from N -acylbenzotriazoles by treating the latter with various amines in the presence of TMSN 3 /Et 3 N in a sealed tube. The salient features of the devised protocol includes the high-yield, mild, metal-free, one-pot reaction conditions, and short reaction time. Furthermore, in many cases, no column chromatography is required for the purification.
- Agrahari, Anand K.,Singh, Anoop S.,Singh, Sumit K.,Tiwari, Vinod K.,Yadav, Mangal S.
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p. 3443 - 3450
(2019/09/07)
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- Sulfated polyborate-catalyzed efficient and expeditious synthesis of (un)symmetrical ureas and benzimidazolones
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The excellent catalytic potential of sulfated polyborate is utilized in the synthesis of (un)symmetrical ureas and benzimidazolones by heating amines or substituted OPDA and urea or N-phenylureas under a solvent-free condition at 120 °C is described. The key advantages of the present protocol are phosgene-free, and other hazardous reagents or organic solvent free, high reaction rates and yields, simple workup procedure, and recyclability of the catalyst.
- Rekunge, Deelip S.,Khatri, Chetan K.,Chaturbhuj, Ganesh U.
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supporting information
p. 4304 - 4307
(2017/10/12)
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- Aromatic oligureas as hosts for anions and cations
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Aromatic oligoureas 3 and 4 have urea moieties engaging in weak intramolecular H-bonding that constrains their backbones. The shorter 3a and 3b are able to bind chloride and acetate but not their corresponding counterion. The longer 4 binds both an anion
- Connor, Alan L.,Hu, Ting,Detchou, Cadnel S.F.,Liu, Rui,Pulavarti, Surya V.S.R.K.,Szyperski, Thomas,Lu, Zhonglin,Gong, Bing
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supporting information
p. 9905 - 9908
(2016/08/11)
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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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- A simple and efficient synthesis of diaryl ureas with reduction of the intermediate isocyanate by triethylamine
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Thirty symmetrical diaryl urea derivatives were synthesised in moderate to excellent yields from arylamine and triphosgene with triethylamine as a reducing agent for the intermediate, isocyanate. It was significant that part of the products could be collected in almost quantitative yield without column chromatography. The procedure under mild reaction conditions was tolerant of a wide range of functional groups. The structures of the compounds were determined by NMR, MS and X-ray crystallographic analyses.
- Zhou, Shuguang,Yao, Ting,Yi, Jicheng,Li, Dashuai,Xiong, Jing
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p. 315 - 319
(2013/07/27)
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- Palladium-catalyzed aromatic azidocarbonylation
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Aryl iodides smoothly react with NaN3 and CO in the presence of a Pd/Xantphos catalyst to give aroyl azides (ArCON3) in 75-92 % yield. The reaction occurs under mild reaction conditions (1 atm, 20-50 °C) and exhibits high functional-group tolerance. (Xantphos=9,9-dimethyl-4,5- bis(diphenylphosphino)xanthene)
- Miloserdov, Fedor M.,Grushin, Vladimir V.
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supporting information; experimental part
p. 3668 - 3672
(2012/05/20)
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- Palladium-catalyzed carbonylation of amines: Switchable approaches to carbamates and N,N′-disubstituted ureas
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Switchable access to carbamates and ureas has been developed by solvent control palladium-catalyzed carbonylation of aromatic amines under an atmosphere of carbon monoxide. A variety of N-phenylcarbamates and N,N′- diphenylureas was easily synthesized in good to excellent yields from readily available aromatic amines under mild conditions. Copyright
- Guan, Zheng-Hui,Lei, Hao,Chen, Ming,Ren, Zhi-Hui,Bai, Yinjuan,Wang, Yao-Yu
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supporting information; experimental part
p. 489 - 496
(2012/04/04)
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- Microwave-assisted preparation of quinolone and quinoline derivatives
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Quinolinone derivatives can be obtained in microwave-assisted syntheses by reaction of aniline derivatives with acetylene dicarboxylic esters, a malonic acid diester or -keto ester derivatives. The reaction proceeds under mild conditions in short reaction
- Albrecht, Markus,Osetska, Olga,Rantanen, Toni,Fr?hlich, Roland,Bolm, Carsten
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scheme or table
p. 1081 - 1084
(2010/07/02)
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- A rapid microwave assisted synthesis of N, N′-diarylureas under solvent-free condition
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A novel microwave assisted phosgene-free synthesis of N,N′- diarylureas under solvent-free conditions has been described.
- Sarveswari,Raja
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p. 546 - 547
(2007/10/03)
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- CeCl3 · 7H2O-KI-catalyzed, environmentally friendly synthesis of N,N′-disubstituted ureas in water under microwave irradiation
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N,N′-Disubstituted ureas were efficiently synthesized by reactions of urea with a variety of amines in water under microwave irradiation using CeCl3 · 7H2O-KI as catalyst. This protocol has advantages of not using toxic phosgene and hazardous organic solvents, high reaction rate, high yield, and a simple workup procedure. Copyright Taylor & Francis, Inc.
- Li, Zheng
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p. 2325 - 2331
(2007/10/03)
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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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- Variation of xantphos-based ligands in the palladium-catalyzed reaction of aryl halides with ureas
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A series of Xantphos-based ligands containing various substituents in the diphenylphosphino groups were synthesized, and their effect on the product yield and ratio in the palladium-catalyzed arylation of ureas with nonactivated aryl halides was studied. The arylation of urea and phenylurea in the presence of Pd2(dba)3-CHCl3, 3,5-(CF3) 2Xantphos, and Cs2CO3 in dioxane at 100°C gave the corresponding N,N′-diarylureas in 62-98% yield.
- Sergeev,Artamkina,Beletskaya
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p. 1741 - 1752
(2007/10/03)
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- Synthesis of functionalized carbamates through a palladium-catalyzed reductive carbonylation of substituted nitrobenzenes
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The palladium-catalyzed reductive carbonylation of ortho and para-substituted nitrobenzenes has proven to be an attractive route for the synthesis of functionalized carbamates. For the Pd(1,10-phenanthroline)2(triilate}2 catalyst system, the scope of the reaction has been studied. Substrates with electron-donating substituents at the para position were found to decrease the catalytic activity, most probably as a result of their relatively low oxidizing capacity. The selectivity towards the desired carbamate, however, was increased for these substrates. Under the influence of electron-withdrawing substituents the azoxybenzene and azobenzene derivatives became important side products. Introduction of large steric hindrance at the ortho position of the nitro substrates gave rise to an interesting side reaction, viz. methoxylation of the aromatic ring. The methoxylation reaction appeared to occur on an intermediate species in the catalytic cycle. Several functionalities have shown to be resistant to the reaction conditions required for the conversion of the nitro group. Especially with 4-nitrobenzoic acid, an extremely high activity and selectivity was found, thus yielding a very convenient synthesis for N-protected amines containing carboxylic acid functions. VCH Verlagsgesellschaft mbH.
- Wchman, Petra,Borst, Leo,Kamer, Paul C. J.,Van Leeuwen, Piet W. N. M.
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- NEW ROUTE FOR THE SYNTHESIS OF SYMMETRICAL DIARYLUREA
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Several esters of aryl carbamic acid were thermally dissociated into symmetrically diarylurea in high yields.The electronic effect and position of the substitution in the aryl groups as well as the role of the alkyl groups on the thermal reaction are discussed.
- Hassan, Alaa A.,Mourad, Aboul-Fetouh E.
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p. 397 - 404
(2007/10/02)
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- Benzimidazole derivatives, their preparation and use
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A compound having the formula STR1 wherein R 1 is hydrogen, NH 2 or C 1-6 -alkyl which may be branched;X is O, S, NCN;Y is O, S;R 4, R 5, R 6 and R 7 independently of each other are hydrogen, halogen, CF 3, NO 2, NH 2, OH, C 1-6 -alkoxy, C( O)-phenyl or SO 2 NR I R II wherein R I and R II independently are hydrogen or C 1-6 -alkyl;R 11 is hydrogen, halogen, NO 2 or SO 2 NR''R"" wherein R'' and R"" independently are hydrogen or C 1-6 -alkyl;R 13 is hydrogen, halogen, phenyl, CF 3, NO 2 ;R 12 is hydrogen or together with R 13 forms a C 4-7 -carbocyclic ring which may be aromatic or partially saturated;R 14 is hydrogen or together with R 13 forms a C 4-7 -carbocyclic ring which may be aromatic or partially saturated;pharmaceutical compositions thereof,and a method of treating a disease in a mammal, including a human, responsive to opening of potassium channels, which comprises administering to a mammal in need thereof an effective amount of a compound as first above indicated, are disclosed.
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- A new route for the synthesis of symmetrical diarylureas
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Several esters of arylcarbamic acid have been thermally dissociated into symmetrical diarylureas in high yields.The electronic effect and position of substitution in the aryl groups as well as the role of alkyl groups on thermal reaction have been discussed.
- Hassan, Alaa A,Mourad, Aboul-fetouh E
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p. 277 - 279
(2007/10/02)
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- Hydrogen bond directed cocrystallization and molecular recognition properties of diarylureas
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The hydrogen bond directed molecular recognition properties of a series of diarylurea (DAU) compounds have been studied using cocrystallization to probe hydrogen bond donor and acceptor selectivity of the host and guest molecules. Diarylureas with meta-substituted electron-withdrawing groups on the aryl rings are capable of forming cocrystal complexes with a wide variety of hydrogen bond acceptors. One particular DAU, 1,3-bis(m-nitrophenyl)urea, behaves primarily as a proton donor, one of the few organic molecules known to have this property. Its hydrogen bond accepting ability is drastically reduced, possibly because of two very weak CH?O interactions occurring in response to the presence of guest acceptor molecules and effectively negating the powerful proton-accepting ability of the urea carbonyl group. Only DAU compounds with meta-substituted electron-withdrawing groups have this property. The crystal structures of four DAU compounds and six of their cocrystal structures are reported. In addition, 19 other DAU cocrystals were prepared and characterized by chemical and spectroscopic means, and their hydrogen bond patterns were assigned based on spectroscopic analogies to those with known crystal structures. From this data hydrogen bond rules for diarylureas have been derived for use in predicting hydrogen bond patterns in related structures.
- Etter, Margaret C.,Urba?czyk-Lipkowska, Zofia,Zia-Ebrahimi, Mohammad,Panunto, Thomas W.
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p. 8415 - 8426
(2007/10/02)
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- The Application of N-Substituted Trichloroacetamides as in situ Isocyanate Generating Reagents for the Synthesis of Acylureas and Sulfonylureas
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In dimethylsulfoxide solution in the presence of excess of powdered sodium hydroxide, N-substituted trichloroacetamides 1 are used as in situ isocyanate generating reagents which can react with carboxamides or sulfonamides 2 to afford acylureas or sulfonylureas 3.
- Atanassova, Ivanka A.,Petrov, Jan S.,Mollov, Nikola M.
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p. 734 - 736
(2007/10/02)
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- Nucleophilic Substitutions at Carbonic Acid Derivatives. XX. Aminolysis of Bis(trichlormethyl)carbonate
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The rate constants for the two steps of the reaction of bis(trichlormethyl)carbonate with substituted anilines have been determinated by conductivity measurements.The first relatively fast step of the reaction is the nucleophilic attack of the amine to the bis(trichloromethyl)carbonate leading to trichloromethylurethane through a six or four centers transition state in wich the carbon-nitrogen bond is formed parallel with the transfer of the proton.In this reaction a phosgene molecule is also produced, which reacts very fast with amine to form a N,N'-diarylurea.The s econd, much slower step, is the nucleophilic attack of the amine to the trichloromethylurethane.Through a similar transition state in which the proton transfer has even a higher importance, a N,N'-disubstituted urea and an other molecule of phosgene are formed.
- Cotarca, Livius,Bacaloglu, R.,Csunderlik, C.,Marcu, N.,Tarnaveanu, A.
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p. 1052 - 1062
(2007/10/02)
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