- “Urea to Urea” Approach: Access to Unsymmetrical Ureas Bearing Pyridyl Substituents
-
A protocol for the synthesis of unsymmetrical ureas substituted by pyridyl/quinolinyl moiety has been developed. This method concluded in metal- and base-free reamination of N,N-dimethyl-N‘-hetaryl ureas with a wide range of aryl and alkyl amines. The isolated yields vary from 40 to 96% depending on the nucleophilicity of the amines. The scope of this method includes more than 50 examples. The reaction is not hindered by either donor or acceptor groups as well as diverse functionalities. The synthesis can be easily scaled to gram quantities. Theoretical calculations supported by experimental data allowed us to propose a plausible mechanism for the process. This reaction takes place through the intermediate formation of hetaryl isocyanate. (Figure presented.).
- Kasatkina, Svetlana O.,Geyl, Kirill K.,Baykov, Sergey V.,Novikov, Mikhail S.,Boyarskiy, Vadim P.
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supporting information
p. 1295 - 1304
(2022/03/15)
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- Hydroamination and Hydrophosphination of Isocyanates/Isothiocyanates under Catalyst-Free Conditions
-
Symmetrical and unsymmetrical N,N’-disubstituted as well as trisubstituted ureas/thioureas by the hydroamination of isocyanates/isothiocyanates, and various phosphathioureas by the hydrophosphination of isothiocyanates have been synthesized in good to excellent yields under catalyst-free and mild conditions. This protocol is also applicable for the efficient synthesis of chiral ureas and thioureas and common herbicides, such as fenuron and monuron.
- Zhu, Xiancui,Xu, Mengchen,Sun, Jinrong,Guo, Dianjun,Zhang, Yiwei,Zhou, Shuangliu,Wang, Shaowu
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p. 5213 - 5218
(2021/10/19)
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- Palladium-Catalyzed cascade carbonylative synthesis of 1,2,4-triazol-3-ones from hydrazonoyl chlorides and NaN3
-
A palladium-catalyzed three-component carbonylative reaction for the synthesis of 3H-1,2,4-triazol-3-ones from hydrazonoyl chlorides and NaN3 has been achieved. The reaction presumably proceeds through a cascade carbonylation, acyl azide format
- Du, Shiying,Wang, Wei-Feng,Song, Yufei,Chen, Zhengkai,Wu, Xiao-Feng
-
supporting information
p. 974 - 978
(2021/02/01)
-
- Nitroarenes as versatile building blocks for the synthesis of unsymmetrical urea derivatives and N-Arylmethyl-2-substituted benzimidazoles
-
In this contribution, a fast and simple method for the synthesis of unsymmetrical urea derivatives and N-arylmethyl-2-substituted benzimidazoles was developed starting from nitroarenes. The reaction of nitroarenes and phenyl isocyanate or phenyl isothiocyanate in tin (II) chloride dihydrate/choline chloride eutectic mixture afforded the expected urea and thiourea derivatives, while the reaction of different aldehydes with o-nitroaniline or 4-methoxy-2-nitroaniline shows a markedly high preference for the obtention of N-arylmethyl-2-substituted benzimidazoles over the 2-substituted analogues. This method offers a straightforward alternative to obtain the target compounds in good to excellent yields with short reaction times employing an operationally simple experimental set-up. Graphic abstract: [Figure not available: see fulltext.] A series of unsymmetrical urea and thiourea derivatives together with 1,2-disubstituted benzimidazoles are easily obtained in good yields starting from nitroarenes employing the eutectic mixture tin (II) chloride dihydrate/choline chloride as reductive reaction media.
- Rodríguez-Huerto, Paula A.,Pe?a-Solórzano, Diana,Ochoa-Puentes, Cristian
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p. 6275 - 6283
(2021/07/29)
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- Searching for small molecules as antibacterials: Non-cytotoxic diarylureas analogues of triclocarban
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Triclocarban (TCC), a broad-spectrum lipophilic antimicrobial agent, is a diarylurea derivative that has been used for more than 60 years as a major ingredient of toys, clothing, food packaging materials, food industry floors, medical supplies and especially of personal care products, such as soaps, toothpaste and shampoo. In September 2016, the U.S. FDA banned nineteen antimicrobial ingredients, including TCC, in over-the-counter consumer antiseptic wash products, due to their toxicity. Withdrawal of TCC has prompted efforts to search for new antimicrobial compounds. In this paper, we present the synthesis and biological evaluation, as antibiotic and non-cytotoxic agents, of a series of diarylureas, analogues of TCC. These compounds are characterized by an intriguingly simple chemistry and can be easily synthesized. Among the synthesized compounds, 1ab and 1bc emerge as the most interesting compounds as they show the same activity of TCC (MIC = 16 μg/mL) against Staphylococcus aureus, and a higher activity than TCC against Enterococcus faecalis (MIC = 32 μg/mL versus MIC = 64 μg/mL). Moreover, 1ab and 1bc show no cytotoxicity towards the human mammary epithelial cells MCF-10A and embryonic kidney epithelial cells Hek-293, in opposition to TCC, which exhibits a marked cytotoxicity on the same cell lines and shows a good antitumor activity on a panel of cell lines tested.
- Catalano, Alessia,Iacopetta, Domenico,Rosato, Antonio,Salvagno, Lara,Ceramella, Jessica,Longo, Francesca,Sinicropi, Maria Stefania,Franchini, Carlo
-
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- Hydroamination of isocyanates and isothiocyanates by alkaline earth metal initiators supported by a bulky iminopyrrolyl ligand
-
A series of new heteroleptic alkaline earth (Ae) metal complexes of general formula [{(Ph2CHN-CH)2C4H2N}AeI(THF)3] {Ae = Ca (2), Sr (3), and Ba (4)} were synthesizedviasalt metathesis by reacting potassium salt of ligand1-K[{(Ph2CHN-CH)2C4H2N}K(THF)2] with anhydrous alkaline earth metal diiodides (AeI2). The homoleptic calcium and barium complexes [{(Ph2CHN-CH)2C4H2N}2Ae] [Ae = Ca (5), Ba (6)] were prepared by treating metal bis-hexamethyldisilazide [Ae{N(SiMe3)2}2(THF)2] with the protic ligand1-H[(Ph2CH-N-CH)2C4H2NH] in a 1:2 molar ratio. Calcium complex5was used as an active pre-catalyst for the addition of N-H bond of arylamines across the heterocumulenes such as phenylisocyanate (PhNCO) and phenylisothiocyanate (PhNCS) under neat conditions, and up to 99% yields of the corresponding urea and thiourea derivatives were obtained.
- Bano, Kulsum,Anga, Srinivas,Jain, Archana,Nayek, Hari Pada,Panda, Tarun K.
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supporting information
p. 9419 - 9428
(2020/06/17)
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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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- Palladium-Catalyzed Synthesis of Symmetrical and Unsymmetrical Ureas Using Chromium Hexacarbonyl as a Convenient and Safe Alternative Carbonyl Source
-
Pd-catalyzed synthesis of urea derivatives from aryl iodides and different aliphatic and aromatic amines using sodium azide and chromium hexacarbonyl is described. In this process, carbonylation of aryl iodides, Curtius rearrangement of aroyl azides, and nucleophilic addition of amines sequentially occur to afford the products in good to excellent yields. This protocol is operationally simple and displays a broad substrates scope.
- Mozaffari, Mozhdeh,Nowrouzi, Najmeh
-
supporting information
p. 7541 - 7544
(2019/12/12)
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- Direct conversion of carboxylic acids to various nitrogen-containing compounds in the one-pot exploiting curtius rearrangement
-
Herein we report, a single-pot multistep conversion of inactivated carboxylic acids to various N-containing compounds using a common synthetic methodology. The developed methodology rendered the use of carboxylic acids as a direct surrogate of primary amines, for the synthesis of primary ureas, secondary/tertiary ureas, O/S-carbamates, benzoyl ureas, amides, and N-formyls, exploiting the Curtius reaction. This approach has a potential to provide a diversified library of N-containing compounds, starting from a single carboxylic acid, based on the selection of the nucleophile.
- Kumar, Arun,Kumar, Naveen,Sharma, Ritika,Bhargava, Gaurav,Mahajan, Dinesh
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p. 11323 - 11334
(2019/09/10)
-
- Synthetic method and application of urea compound
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The invention relates to a synthetic method of a urea compound, comprising the following steps: adding substituted oxazolone and sodium acetate into a methanol solution, and adding substituted amine under the stirring condition, reacting and carrying out column chromatography to obtain the urea compound. The defect that dangerous compounds need to be used during existing synthetic process is overcome, and a one-pot method is adopted to replace an existing reaction with low yield. The method of the invention has mild reaction condition, the operation is simple, raw materials are easily available, and the substrate can be converted into various other useful molecules. The compound has strong practicality, and can be applied to synthesis of the pesticide daimuron, dieresis long and the anti-cancer drug Sorafenib. The invention relates to a green and environmentally-friendly unsymmetrical urea compound synthesis method with simple process and low cost.
- -
-
Paragraph 0078-0080; 0082
(2019/06/07)
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- An efficient one-pot synthesis of N,N′-disubstituted phenylureas and N-aryl carbamates using hydroxylamine-O-sulfonic acid
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We have developed an efficient one-pot method for the microwave-assisted synthesis of ureas and carbamates via a proposed Lossen rearrangement. Herein we report the first examples of the direct conversion of benzoyl chlorides into N,N′-disubstituted ureas and N-aryl carbamates using hydroxylamine-O-sulfonic acid as reagent. Using our general method, we have produced 11 examples of N,N′-disubstituted phenylureas in yields up to 95% using various substituted anilines, and primary and secondary amines. Additionally, we were able to generate a series of N-aryl carbamates in moderate yields using primary, secondary and tertiary alcohols.
- Bao, Jennifer,Kuik, Dale,Tranmer, Geoffrey K.
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supporting information
p. 5546 - 5553
(2018/06/12)
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- Spontaneous and direct transformation of N,O-diaryl carbamates into N,N′-diarylureas
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We have discovered a spontaneous reaction of N,O-diaryl carbamates to afford symmetrical N,N′-diarylureas. Optimization of the conditions indicated that N,N-dimethylformamide (DMF) was the best solvent and triethylamine (Et3N) was the best additive for this transformation. The reaction requires the presence of aryl groups on the nitrogen and oxygen atoms of carbamates. Substrates bearing an electron-donating methoxy group on either of the aryl groups reacted slowly under these conditions.
- Yamasaki, Ryu,Honjo, Yutaka,Ito, Ai,Fukuda, Kazuo,Okamoto, Iwao
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p. 880 - 884
(2018/09/10)
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- Facile direct synthesis of unsymmetrical ureas from N-Alloc-, N-Cbz-, and N-Boc-protected amines using DABAL-Me3
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A practical synthetic method for the direct synthesis of unsymmetrically substituted ureas from N-Alloc-, N-Cbz-, and N-Boc-protected amines is described. In this study, efficient direct conversion of the Alloc-, Cbz-, and Boc-carbamate compounds to ureas was achieved in the presence of DABAL-Me3, an air stable and easily handled reagent. Using this reaction method, both protected aromatic and aliphatic amines were successfully transformed into various trisubstituted and tetrasubstituted ureas with high yields without side product. Our findings offer promising guidelines for direct preparation of useful ureas from N-Alloc-, N-Cbz-, and N-Boc-carbamates.
- Kang, Soosung,Kim, Hee-Kwon
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p. 4036 - 4046
(2018/06/13)
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- Investigation of O-Sulfonylation-promoted Heterolytic N?O Bond Cleavage of Amidoximes and Ketoximes
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Two different reaction pathways were observed in the sulfonylation of N-phenylbenzamidoximes. The reaction with o-NsCl at a heating temperature gave N,N′-diphenylureas via Tiemann rearrangement, while the reaction with Ts2O at a lower temperature formed 2-phenylbenzimidazoles via intramolecular electrophilic aromatic substitution. When the amide nitrogen was replaced with carbon substituents, oxime derivatives of benzoins and benzils underwent Beckmann fragmentation reactions upon sulfonylation, whereas sulfonylation of 2-phenylacetophenone oxime afforded exclusively the Beckmann rearrangement adduct.
- Hsieh, Tsung-Han,Liao, Pen-Yuan,Liu, Yu-Ting,Wang, Chien-Hong,Lin, Chia-Chi,Chien, Tun-Cheng
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p. 325 - 330
(2017/10/11)
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- Chloromethylated polystyrene immobilized ruthenium complex of 2-(2-pyridyl)benzimidazole catalyst for the synthesis of bioactive disubstituted ureas by carbonylation reaction
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Polymer supported transition metal complex catalysts have numerous applications as heterogeneous catalysts due to their ease of synthesis and commercial availability. Ru-Py-Merf was synthesized by anchoring 2-(2-pyridyl)benzimidazole to the polymer matrix, followed by loading of ruthenium salt. This Ru-Py-Merf material was thoroughly characterized by FTIR spectroscopy, UV-vis absorption spectroscopy, FE-SEM analysis, EDAX analysis, CHN analysis, AAS spectroscopy and TGA. Ru-Py-Merf showed excellent catalytic activity in the synthesis of symmetric and asymmetric disubstituted ureas by reductive carbonylation of nitrobenzenes and anilines. The as-synthesized Ru-Py-Merf catalyst is entirely heterogeneous in nature, thermally stable and can be easily reused up to six times.
- Dey, Tusar Kanto,Ghosh, Kajari,Basu, Priyanka,Molla, Rostam Ali,Islam, Sk. Manirul
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p. 9168 - 9176
(2018/06/08)
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- Synthesis and architecture of polystyrene-supported Schiff base-palladium complex: Catalytic features and functions in diaryl urea preparation in conjunction with Suzuki-Miyaura cross-coupling reaction by reductive carbonylation
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This work represents an efficient and unique phosphine-free approach for the polystyrene embedded Schiff-base palladium catalyzed diaryl urea synthesis and Suzuki-Miyaura cross-coupling reaction by reductive carbonylation process. The careful instrumental investigations with FE-SEM, TEM, EDAX, TGA, UV–Vis, FTIR, AAS, and elemental analysis precisely characterized the developed heterogeneous catalyst. Reaction parameters, like catalytic natures, starting materials, reaction environment, and solvent were examined sequentially. The present work has been adequately addressed to account for the generation and characterization of a new polymer bound Pd-catalyst and using it in the synthesis of diaryl ureas and diaryl ketones, with no substantial decay of catalytic activity.
- Basu, Priyanka,Riyajuddin, Sk,Dey, Tusar Kanto,Ghosh, Aniruddha,Ghosh, Kaushik,Islam, Sk Manirul
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- Scalable, One-Pot, Microwave-Accelerated Tandem Synthesis of Unsymmetrical Urea Derivatives
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We report a facile, microwave-accelerated, one-pot tandem synthesis of unsymmetrical ureas via a Curtius rearrangement. In this method, one-pot microwave irradiation of commercially available (hetero)aromatic acids and amines in the presence of diphenylphosphoryl azide enabled extremely rapid (1-5 min) construction of an array of unsymmetrical ureas in good to excellent yields. We demonstrate the utility of our method in the efficient, gram-scale synthesis of key biologically active compounds targeting the cannabinoid 1 and α7 nicotinic acetylcholine receptors.
- Kulkarni, Abhijit R.,Garai, Sumanta,Thakur, Ganesh A.
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p. 992 - 999
(2018/06/18)
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- An efficient synthesis of nitrile, tetrazole and urea from carbonyl compounds
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An efficient conversion of carbonyl compounds (aldehydes and ketones) to nitrile, tetrazole, and urea was developed with the use of a POCl3 and sodium azide mixture using a convergent and microwave method. This is the first report on the direct conversion of ketone to urea. The synthesized compounds were characterized by 1H NMR, 13C NMR, mass and IR spectroscopies and were found to be in agreement with reported compounds.
- Sribalan, Rajendran,Sangili, Arumugam,Banuppriya, Govindharasu,Padmini, Vediappen
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p. 3414 - 3421
(2017/07/13)
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- Oximes as reusable templates for the synthesis of ureas and carbamates by an: In situ generation of carbamoyl oximes
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Oximes have been identified as reusable templates for the synthesis of ureas and carbamates by an in situ generation of carbamoyl oximes under metal-free conditions. The recovered oxime has been utilised for three trials in the synthesis of urea derivatives without any loss in the yield and efficiency. In addition, this template approach could override the usage of hazardous and less stable isocyanates as substrates.
- Senadi, Gopal Chandru,Mutra, Mohana Reddy,Lu, Ting-Yi,Wang, Jeh-Jeng
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supporting information
p. 4272 - 4277
(2017/09/28)
-
- Highly Regioselective Iodination of N-Phenylureas with Iodine/Trichloroisocyanuric Acid
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An efficient regioselective iodination of N-phenylureas was developed using iodine/trichloroisocyanuric acid in acetonitrile at room temperature. This protocol proved to be effective on a broad range of substituted N-phenylureas, forming the p-iodinated compounds in 65-96% yield under mild and neutral conditions.
- Sanabria, Carlos M.,do Casal, Mariana T.,De Souza, Raphael B. A.,De Aguiar, Lúcia C. S.,De Mattos, Marcio C. S.
-
supporting information
p. 1648 - 1654
(2017/03/21)
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- Ethyl 2-(tert-Butoxycarbonyloxyimino)-2-cyanoacetate (Boc-Oxyma): An Efficient Reagent for the Racemization Free Synthesis of Ureas, Carbamates and Thiocarbamates via Lossen Rearrangement
-
Boc-Oxyma (Ethyl 2-(tert-butoxycarbonyloxyimino)-2-cyanoacetate) has been reported previously as an efficient coupling reagent for the synthesis of amides, peptides, esters, thioesters and hydroxamic acids. It is known for its excellent racemization suppression capability, and also as an environment friendly reagent as it generates only Oxyma as solid byproduct that can be recovered easily and recycled for the synthesis of the same reagent. In this update, we report a simple, efficient, environment friendly, chemoselective and racemization free method for the synthesis of ureas, carbamates and thiocarbamates from hydroxamic acids via Lossen rearrangement by using Boc-Oxyma. We have achieved racemization free di- and tri-peptidyl ureas with very good yield by using this protocol. A rigorous mechanistic investigation is also incorporated. (Figure presented.).
- Manne, Srinivasa Rao,Thalluri, Kishore,Giri, Rajat Subhra,Chandra, Jyoti,Mandal, Bhubaneswar
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p. 168 - 176
(2017/01/14)
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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)
-
- A Facile and Efficient Method for the Formation of Unsymmetrical Ureas Using DABAL-Me3
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A practical synthetic method for the formation of unsymmetrical-substituted ureas is described. The synthesis of the unsymmetrical ureas was readily performed from 2,2,2-trichloroethyl carbamate compounds by treatment of amines with bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane (DABAL-Me3). Using this reaction protocol, various trisubstituted and tetrasubstituted ureas were synthesized in high yields. This study offers a promising approach for the facile synthesis of a variety of unsymmetrical ureas from 2,2,2-trichloroethyl carbamates.
- Jeong, Byung-Hoon,Kim, Hee-Kwon,Thompson, David H.
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p. 805 - 810
(2016/08/09)
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- Synthesis of unsymmetrical ureas and S-thiocarbamates under catalyst-free conditions in a [BMIM]BF4 ionic liquid
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Unsymmetrical ureas and Sthiocarbamates were prepared in good to excellent yields by direct condensation of phenylurea with amines and thiols in 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]BF4) without the addition of any additives. The [BMIM]BF4 ionic liquid is a mild medium and can be recycled and reused several times.
- Hosseinzadeh, Rahman,Tajbakhsh, Mahmood,Aghili, Nora
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p. 175 - 182
(2015/05/27)
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- Polystyrene anchored ruthenium(II) complex catalyzed carbonylation of nitrobenzene and amines for the synthesis of disubstituted ureas
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The catalytically active complex [Ru(PS-imd)(CO)2Cl2] (PS-imd = polystyrene anchored imidazole) was synthesized and characterized using various spectroscopic techniques. The complex is well characterized and highly stable. The catalytic activity of the resulting species was investigated towards the synthesis of diphenyl urea and other disubstituted ureas. The experiments were carried out under high CO pressure, high temperature condition in mild coordinating media. The catalyst was found to produce excellent yields with high product selectivity. Variable yields are obtained depending on the substituent on nitrobenzene and aniline. The effects of co-solvent and co-catalyst were also studied. The catalyst was very stable and could be reused for more than five times without any noticeable loss of its catalytic activity.
- Islam, Sk Manirul,Ghosh, Kajari,Roy, Anupam Singha,Molla, Rostam Ali,Salam, Noor,Chatterjee, Tanmay,Iqubal, Md. Asif
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p. 152 - 160
(2015/01/09)
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- Polystyrene anchored ruthenium(II) complex catalyzed carbonylation of nitrobenzene and amines for the synthesis of disubstituted ureas
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The catalytically active complex [Ru(PS-imd)(CO)2Cl2] (PS-imd = polystyrene anchored imidazole) was synthesized and characterized using various spectroscopic techniques. The complex is well characterized and highly stable. The catalytic activity of the resulting species was investigated towards the synthesis of diphenyl urea and other disubstituted ureas. The experiments were carried out under high CO pressure, high temperature condition in mild coordinating media. The catalyst was found to produce excellent yields with high product selectivity. Variable yields are obtained depending on the substituent on nitrobenzene and aniline. The effects of co-solvent and co-catalyst were also studied. The catalyst was very stable and could be reused for more than five times without any noticeable loss of its catalytic activity.
- Islam, Sk Manirul,Ghosh, Kajari,Roy, Anupam Singha,Molla, Rostam Ali,Salam, Noor,Chatterjee, Tanmay,Iqubal, Md. Asif
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p. 152 - 160
(2015/01/30)
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- Practical synthesis of N -substituted cyanamides via tiemann rearrangement of amidoximes
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A facile and general synthesis of various N-substituted cyanamides was accomplished by the Tiemann rearrangement of amidoximes with benzenesulfonyl chlorides (TsCl or o-NsCl) and DIPEA.
- Lin, Chia-Chi,Hsieh, Tsung-Han,Liao, Pen-Yuan,Liao, Zhen-Yuan,Chang, Chih-Wei,Shih, Yu-Chiao,Yeh, Wen-Hsiung,Chien, Tun-Cheng
-
p. 892 - 895
(2014/03/21)
-
- Benzoic acid-catalyzed transamidation reactions of carboxamides, phthalimide, ureas and thioamide with amines
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An efficient and simple method for the transamidation of carboxamides, phthalimide, ureas and thioamide with amines catalyzed by commercially available benzoic acid under metal-free conditions is described. Furthermore, to the best of our knowledge, this is the first report about the transamidation of an aromatic thioamide with amines.
- Wu, Ji-Wei,Wu, Ya-Dong,Dai, Jian-Jun,Xu, Hua-Jian
-
supporting information
p. 2429 - 2436
(2014/09/30)
-
- Cu(acac)2-catalyzed N-arylations of phenylurea with aryl boronic acid
-
Cu(acac)2 activates aryl boronic acids for the reaction with NH2-phenylurea without additional ligand and heating. The procedure is simple, general, ligand-free, milder than the palladium-catalyzed arylation, and avoids the use of toxic phosphine ligands. Copyright Taylor & Francis Group, LLC.
- Gavade, Sandip,Balaskar, Ravi,Mane, Madhav,Pabrekar, Pramod N.,Mane, Dhananjay
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experimental part
p. 1704 - 1714
(2012/05/05)
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- Synthesis of unsymmetrical biaryl ureas from N-carbamoylimidazoles: Kinetics and application
-
N-Carbamoylimidazoles dissociate in solution to yield imidazole and an isocyanate that may be reacted with another aryl amine to form an unsymmetrical biaryl urea. This paper investigates the reaction kinetics and the influence of electron withdrawing/donating substituents on the reaction of N-carbamoylimidazoles with aniline. The overall reaction mechanism involves two zwitterionic intermediates, formed during dissociation and upon reaction of the liberated isocyanate with aniline. The rate limiting step for the reaction is a base catalysed proton transfer from the second zwitterionic intermediate. Although electron withdrawing substituents on the aryl group hinder dissociation, they significantly increase reaction rates compared to compounds bearing electron donating substituents. The imidazole liberated upon dissociation catalyses the rate determining step so that reactions of dissociated N-carbamoylimidazoles proceed more rapidly than those involving only isocyanates. In addition, the imidazole eliminates the need for anhydrous reaction conditions. The N-carbamoylimidazole methodology was demonstrated by preparing sorafenib, a biaryl urea kinase inhibitor, in good yield and excellent purity.
- Rawling, Tristan,McDonagh, Andrew M.,Tattam, Bruce,Murray, Michael
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p. 6065 - 6070
(2012/09/22)
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- Bromodimethylsulfonium bromide (BDMS)-mediated Lossen rearrangement: Synthesis of unsymmetrical ureas
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Bromodimethylsulfonium bromide (BDMS) was found to be a very efficient reagent for Lossen rearrangement of hydroxamic acids to the corresponding isocyanates which were subsequently trapped in situ with various amines to afford unsymmetrical ureas in good to excellent yields (64-89%). The protocol is experimentally simple, mild, and represents valuable alternative to the existing methods for in situ activation of hydroxamic acids promoting Lossen rearrangement.
- Yadav, Deepak K.,Yadav, Arvind K.,Srivastava, Vishnu P.,Watal, Geeta,Yadav, Lal Dhar S.
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experimental part
p. 2890 - 2893
(2012/07/27)
-
- Efficient copper(II)-catalyzed transamidation of non-activated primary carboxamides and ureas with amines
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Amid(e) them all: Primary carboxamides and ureas react with aromatic and aliphatic amines in the presence of a copper catalyst to give a wide range of functionalized amides (see scheme). Copyright
- Zhang, Min,Imm, Sebastian,Baehn, Sebastian,Neubert, Lorenz,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 3905 - 3909
(2012/06/04)
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- Microwave assisted, ligand free, copper catalyzed reaction of aryl halides with phenyl urea
-
The ligand free coupling reaction of phenyl urea with different functionalized aryl halides in the presence of air stable Cu2O and t-BuOK as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields. This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligand.
- Gavade, Sandip N.,Balaskar, Ravi S.,Mane, Madhav S.,Pabrekar, Pramod N.,Shingare, Murlidhar S.,Mane, Dhananjay V.
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experimental part
p. 292 - 295
(2012/01/05)
-
- Microwave assisted, solvent- and ligand-free copper catalyzed N-arylation of phenylurea with aryl halides
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An inexpensive and efficient catalyst system has been developed for the N-arylation of phenylurea including a variety of aryl halides. This simple protocol uses Cu2O as the catalyst, microwave assisted, solvent- and ligand-free, K3PO4.H2O as the base.
- Gavade, Sandip,Shingare, Murlidhar,Mane, Dhananjay
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experimental part
p. 4167 - 4170
(2012/02/16)
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- An efficient method for the N-arylation of phenylurea via copper catalyzed amidation
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The coupling reaction of phenylurea with different functionalized aryl halides in the presence of air stable CuI, N,N-dimethylethylenediamine as a ligand, and K3PO4 as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields. This method is milder than the palladium catalyzed arylation and avoids the use of toxic phosphine ligands.
- Gavade, Sandip N.,Balaskar, Ravi S.,Mane, Madhav S.,Pabrekar, Pramod N.,Shingare, Murlidhar S.,Mane, Dhananjay V.
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experimental part
p. 675 - 678
(2012/01/13)
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- Flash vacuum pyrolysis of 1,2,5-oxadiazole 2-oxides and 1,2,3-triazole 1-oxides
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The flash vacuum pyrolysis (FVP, 450-600 °C/10-3 mmHg) of 3,4-diaryl- and 3,4-dialkyl-1,2,5-oxadiazole 2-oxides (furoxans) has been investigated. In all cases the 1,2,5-oxadiazole ring cleaved cleanly at O(1)-N(2) and C(3)-C(4) to afford two nitrile oxide fragments, which were trapped in high yield (75-97%) as their isoxazoline cycloadducts by reaction with alk-1-enes. At higher temperatures (700-800 °C) isocyanates were formed as by-products. The dimerisation of acetonitrile oxide to dimethylfuroxan was followed by 1H NMR spectroscopy, and the rate constant for the 2 nd order reaction determined. The furoxans were converted into isocyanates in good yield (61-95%) by FVP, followed by sulfur dioxide-mediated isomerisation of the resulting nitrile oxides. 2,4,5-Trisubstituted-1,2,3- triazole 1-oxides showed greater thermal stability, but at 700-800 °C decomposition of the 4,5-dimethyl compound 25b lead to 1,2-di(5-methyl-2-phenyl- 1,2,3-triazol-2-yl)ethane as the major product; attempts to trap acetonitrile oxide were unsuccessful. ARKAT USA, Inc.
- Mitchell, William R.,Paton, R. Michael
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experimental part
p. 34 - 54
(2011/02/21)
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- An efficient and mild protocol for the synthesis of unsymmetrical ureas in the absence of catalyst and additives
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A new practical method for the synthesis of unsymmetrical ureas was achieved by reaction of phenylurea with primary and secondary amines under neutral and mild condition in very good yields. The reaction took place in refluxing dioxane and does not require any catalyst or additives.
- Hosseinzadeh, Rahman,Sarrafi, Yaghoub,Aghili, Nora
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experimental part
p. 1171 - 1174
(2011/10/04)
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- Trapping! of isocyanates with benzotriazole in situ - Preparation of carbamoyl benzotriazoles as an isocyanate alternative via curtius rearrangement
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N-Aryl and N-alkenyl carbamoyl benzotriazoles were prepared in good to excellent yields from acyl azides and benzotriazole via Curtius rearrangement, while N-alkylcarbamoyl benzotriazoles were formed from N-alkanoyl benzotriazoles and sodium azide in one
- Zhong, Zhiyun,Wang, Xiaoxia,Kong, Lichun,Zhu, Xiangming
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experimental part
p. 2461 - 2464
(2010/01/07)
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- A general method for the synthesis of unsymmetrically substituted ureas via palladium-catalyzed amidation
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A general and practical method for the preparation of unsymmetrically substituted ureas has been developed utilizing palladium-catalyzed amidation. Both aryl bromides and chlorides, as well as heteroaryl chlorides, have been coupled to aryl, benzyl, and a
- Kotecki, Brian J.,Fernando, Dilinie P.,Haight, Anthony R.,Lukin, Kirill A.
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supporting information; experimental part
p. 947 - 950
(2009/08/07)
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- Kinetics and mechanism of the anilinolysis of S-aryl N-arylthiocarbamates in acetonitrile
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The aminolysis reactions of S-aryl N-arylthiocarbamates (YC 6H4NH-C(=O)-SC6H4Z, 1) with anilines in acetonitrile are studied. The reaction rates are more influenced by the nucleophilicity of the nucleophile than the nucleofugality of the leaving group, but the change In the effective charge from reactants to the TS for formation of the tetrahedral intermediate is slightly greater in the leaving group (βz from-0.07 to -0.14) than In the nucleophile (βx = 0.04-0.12). The magnitude of the Broensted coefficients are in the range of values that are consistent for a stepwise mechanism with rate-limiting formation of the zwitterionic tetrahedral intermediate. Signs of cross-interaction constants, ρxy (>0), ρxz (>0) and ρyz (0), are all consistent with a stepwise mechanism. It Is concluded that the change of the amine from benzylamines to anilines causes a shift of the aminolysis mechanism from a concerted to a stepwise process. Copyright
- Sung, Dae Dong,Jang, Hee Man,Jung, Dae Il,Leeb, Ikchoon
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supporting information; experimental part
p. 1014 - 1019
(2009/10/26)
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- Copper-catalyzed arylation of phenylurea using KF/Al2O3
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A mild and efficient method for the copper-catalyzed arylation of phenylurea is described. The coupling reaction of phenylurea with different functionalized aryl iodides in the presence of air stable CuI, N,N′-dibenzylethylenediamine as a ligand, and KF/Al2O3 as a base gives symmetrical and unsymmetrical diarylureas in relatively high yields.
- Hosseinzadeh, Rahman,Sarrafi, Yaghoub,Mohadjerani, Maryam,Mohammadpourmir, Fatemeh
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p. 840 - 843
(2008/04/13)
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- Silica gel confined ionic liquid + metal complexes for oxygen-free carbonylation of amines and nitrobenzene to ureas
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A new kind of silica gel confined ionic liquid containing a metal complex as heterogenized catalysts was prepared for the carbonylation of amines and nitrobenzene without molecular oxygen to afford the corresponding ureas with greatly enhanced catalytic activity (TOF exceeded 11000 mol·mol -1· h-1), with a much lower amount of ionic liquids being needed, with easy catalyst separation and possible reusability, and avoidance of the using of explosive CO + O2 gas mixtures. Such an enhancement in catalytic activity may be derived from the effect of a high concentration of ionic liquid containing a metal complex due to the confinement into the nanopores or cavities of the silica gel matrix.
- Shi, Feng,Zhang, Qinghua,Gu, Yanlong,Deng, Youquan
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p. 225 - 230
(2007/10/03)
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- Variation of xanthene-based bidentate ligands in the palladium-catalyzed arylation of ureas
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A series of xanthene-based bidentate ligands containing various substituents on diphenylphosphino groups were synthesized and tested in the palladium-catalyzed arylation reaction of urea with unactivated aryl bromides. It was found that both steric and electronic properties of the ligands have a pronounced effect on the yields and ratios of the products. Arylation of urea and phenylurea with unactivated aryl bromides in the presence of Pd2dba3·CHCl3/3,5-(CF3) 2Xantphos and Cs2CO3 as base in dioxane at 100°C gave the corresponding N,N′-diarylureas in 62-98% yields.
- Sergeev, Alexey G.,Artamkina, Galina A.,Beletskaya, Irina P.
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p. 4719 - 4723
(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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- Palladium-catalyzed arylation of ureas
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Urea arylation with aryl halides in the presence of catalyst precursor Pd2dba3-CHCl3/Xantphos and Cs 2CO3 in dioxane at 100°C affords symmetrical N,N′-diarylureas in 64-92% yield. With the same cataly
- Artamkina,Sergeev,Beletskaya
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p. 538 - 545
(2007/10/03)
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- Palladium-catalyzed reaction of aryl halides with ureas
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A new method for the palladium-catalyzed arylation of ureas is described. The coupling reaction of urea and phenylurea with aryl halides containing electron-withdrawing groups in the p-position in dioxane in the presence of 0.5-1.0 mol% of Pd2dba3·CHCl3, Xantphos and Cs2CO3 as a base gives N,N′-diarylureas in yields of 64-92%.
- Artamkina, Galina A.,Sergeev, Alexey G.,Beletskaya, Irina P.
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p. 4381 - 4384
(2007/10/03)
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- Acyl Carbamoyl Selenides and Related Sulfur Isologues: Synthesis and X-Ray Structural Analyses
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Selenocarboxylic acids [RC(=O)SeH] were found to readily react with aryl, acyl, and arenesulfonyl isocyanates to give the corresponding acyl carbamoyl selenides 3 [RC(=O)SeC(=O)NHR', R'= aryl, C6H5CO, and 4-MeC6H4SO2] in good yields. Their tautomers [RC(=O)SeC(=NR')OH] were also detected by 1H, 13C, and 77Se NMR spectroscopies. The structure of 3 [R = 2,6-(MeO)2C6H3, R' = 4-MeC6H4] was characterized by X-ray crystallography, which showed that this molecule is stabilized by an intramolecular hydrogen bond between the carbonyl oxygen and the NH hydrogen to form a planar six-membered ring and by nonbonded interaction of ortho methoxy oxygen with the carbonyl oxygen or the selenium atoms. 4-Methoxybenzoyl and 4-methoxythiobenzoyl N-(4-methylphenyl)carbamoyl sulfides (4 and 5) were shown by X-ray crystallography to similarly have a planar intramolecular six-membered ring formed by a hydrogen bond between the carbonyl oxygen or thiocarbonyl sulfur and NH hydrogen atoms. The tautomers [RC(=E)SC(=NR')OH; E = O or S] of 4 and 5 also were detected spectroscopically. The recations of 3h (R = 4-MeOC6H4, R' = Ph) with sodium methoxide and p-toluidine gave sodium selenocarboxylate and the corresponding amides and urea as main products, respectively.
- Kageyama, Hideki,Tani, Kazuyasu,Kato, Shinzi,Kanda, Takahiro
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p. 250 - 258
(2007/10/03)
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- Ruthenium catalysed N,N'-Diarylurea Synthesis from N-Aryl substituted Formamides and Aminoarenes
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N-Aryl substituted formamides react smoothly with aminoarenes in the presence of a catalytic amount of dichlorotris(triphenylphosphine)ruthenium to afford various N,N'-diarylureas in good yields.
- Kotachi, Shinji,Tsuji, Yasushi,Kondo, Teruyuki,Watanabe, Yoshihisa
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p. 549 - 550
(2007/10/02)
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- The reaction of imidates with isocyanates
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Derivatives of isocyanates were prepared by reaction with imidates. Fragmentation reactions and behaviour in a simple biological test were examined.
- Schweim
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p. 319 - 321
(2007/10/02)
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- Formation of Imidates, Amides, Amines, Carbamates, and Ureas from the μ3-NPh Ligands of Fe3(μ-NPh)2(CO)9
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The bis(nitrene) cluster Fe3(μ3-NPh)2(CO)9 (1) reacts with Li, MeLi, PhLi, and NaOMe to form the formyl and acyl clusters 3-NPh)2(CO)8CR>- (4, R=H; 6, R=Ph; 7, R=Me; 8, R=OMe).Formyl cluster 4 is unstable at room temperature and slowly loses CO to form the hydride cluster 3-NPh)2(CO)8>-.The benzoyl cluster 7 reacts with EtOTf to yield the nitrene-carbene cluster Fe3(μ3-NPh)2(CO)8(CPh) (9) which has been structurally characterized: Pbca, a=13.668(6) Angstroem, b=17.588(7) Angstroem, c=25.644(8) Angstroem, V=6164(7) Angstroem3, Z=8, R=0.060, Rw=0.075 for 2982 reflections with Fo>2?(Fo).The carbene ligand is bound to a basal iron atom, and the carbene carbon lies within the Fe3 plane.The carbene and nitrene ligands in 9 couple to form the imidate PhN=C(OEt)Ph when 9 is exposed to air or allowed to stand in solution for prolonged periods under CO or N2 atmospheres.A crossover experiment showed this coupling to be strictly intramolecular.Similar nitrene-benzoyl coupling from 7 gives benzanilide, and the methoxycarbonyl and nitrene ligands in 8 couple to give methyl N-phenylcarbamate when the clusters are oxidatively degraded with +.The latter reaction models mechanictis suggestions previously made for the M3(CO)12 (M=Fe, Ru) catalyzed carbonylation of PhNO2 to yield carbamates.The bis(phosphinidene) cluster Fe3(μ-PPh)2(CO)9 (2) also reacts with PhLi to yield a benzoyl derivative, 3-PPh)2(CO)8(CPh)>-.However, addition of EtOTf to this species does not result in a carbene cluster analogous to 9, but instead phosphinidene-carbene coupling occurs to give Fe3(μ3-PPh)(μ3-PhPCPh)(CO)9 which has been structurally characterized: P, a=9.241(2) Angstroem, b=10.233(3) Angstroem, c=19.564(5) Angstroem, α=84.53(2) deg, β=84.43(2) deg, γ=76.41(2) deg, V=1784.7(8) Angstroem3, Z=2, R=0.0557, Rw=0.0602 for 3710 reflections with Fo>3?(Fo).The phosphorous atom of the μ3-PhPCPh ligand bridges two iron atoms, and the ethoxy-substituted carbon is attached to the third iron atom.
- Williams, Gregory D.,Whittle, R. R.,Geoffroy, Gregory L.,Rheingold, Arnold L.
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p. 3936 - 3945
(2007/10/02)
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