- 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
-
p. 5213 - 5218
(2021/10/19)
-
- 2,2,2-Trifluroenthanol promoted synthesis of unsymmetrical ureas from dioxazolones and amines via tandem lossen rearrangement/condensation process
-
A 2,2,2-trifluroenthanol (TFE) promoted synthesis of unsymmetric ureas was described. This approach enabled the construction of a variety of ureas from the readily prepared and easy-to-handle dioxazolones and amines via tandem Lossen rearrangement/condensation process. The reaction featured mild conditions for the urea synthesis under metal-free conditions, which was successively applied in the scale-up synthesis of herbicides Monuro and Isoproturon.
- Li, Jian,He, Wang,Lei, Pan,Song, Jiacheng,Huo, Jiyou,Wei, Hongbo,Bai, Hongjin,Xie, Weiqing
-
supporting information
p. 3590 - 3600
(2021/10/07)
-
- Photocatalyzed synthesis of unsymmetrical ureas via the oxidative decarboxylation of oxamic acids with PANI-g-C3N4-TiO2 composite under visible light
-
The synthesis of unsymmetrical ureas via the photocatalyzed oxidative decarboxylation of oxamic acids has been developed. The carbamoyl radicals were generated from oxamic acids in the presence of a hypervalent iodine reagent and the PANI(Polyaniline)-g-C3N4-TiO2 composite under visible light irradiation. The radicals were converted in situ into the corresponding isocyanates, which were then trapped by amines to afford the corresponding products in moderate to good yields. This protocol avoided the direct use of environmentally unfriendly isocyanates and a series of substrates were tolerated. Moreover, the photocatalyst could be readily recovered by simple filtration and be reused for several runs with only a slight decrease in the catalytic activity.
- Wang, Liang,Wang, Hao,Wang, Yaoyao,Shen, Minggui,Li, Shubai
-
supporting information
(2020/04/28)
-
- Electrochemical Synthesis of Carbodiimides via Metal/Oxidant-Free Oxidative Cross-Coupling of Amines and Isocyanides
-
This work discloses an electrochemical oxidative cross-coupling of amines with aryl and aliphatic isocyanides. In an undivided cell, the reaction proceeds without involving any transition-metal catalyst, oxidant, or toxic reagents providing carbodiimides in good yields, thereby circumventing stoichiometric chemical oxidants, with H2 as the only byproduct. Moreover, carbodiimides were in situ converted into unsymmetrical ureas in moderate to good yields using an electricity ON-OFF strategy.
- Badsara, Satpal Singh,Jaiswal, Pradeep K.,Malviya, Bhanwar Kumar,Sharma, Siddharth,Verma, Ved Prakash
-
supporting information
(2020/03/19)
-
- Lanthanum(III) Trifluoromethanesulfonate Catalyzed Direct Synthesis of Ureas from N-Benzyloxycarbonyl-, N -Allyloxycarbonyl-, and N -2,2,2-Trichloroethoxycarbonyl-Protected Amines
-
A novel lanthanum triflate mediated conversion of N -benzyloxycarbonyl-, N -allyloxycarbonyl-, and N -trichloroethoxycarbonyl-protected amines into nonsymmetric ureas was discovered. In this study, lanthanum triflate was found to be an effective catalyst for preparing various nonsymmetric ureas from protected amines. A variety of protected aromatic and aliphatic carbamates reacted readily with various amines in the presence of lanthanum triflate to generate the desired ureas in high yields. This result demonstrated that this novel lanthanum triflate catalyzed preparation of ureas from Cbz, Alloc, and Troc carbamates can be employed for the formation of various urea structures.
- Bui, Tien Tan,Kim, Hee-Kwon
-
supporting information
p. 997 - 1002
(2020/06/17)
-
- Visible-light-promoted oxidative desulphurisation: A strategy for the preparation of unsymmetrical ureas from isothiocyanates and amines using molecular oxygen
-
A green and efficient visible-light promoted oxidative desulphurisation protocol has been proposed for the construction of unsymmetrical ureas under mild conditions with broad substrate scope and good functional group tolerance. Most appealingly, the reaction can proceed smoothly without adding any strong oxidants. Control experiments and computational studies support a mechanism involving water-assisted in situ generation of thioureas and photocatalytic oxidative desulphurisation. The present method provides a promising synthesis strategy for the formation of diverse and useful unsymmetrical urea derivatives in the fields of pharmaceutical and synthetic chemistry.
- Deng, Weiseng,Gan, Ziyu,Jiang, Yuan-Ye,Li, Guoqing,Yan, Qiuli,Yang, Daoshan
-
supporting information
p. 2956 - 2962
(2020/06/17)
-
- Facile synthesis of phthalidyl fused spiro thiohydantoins through silica sulfuric acid induced oxidative rearrangement of ninhydrin adducts of thioureas
-
A one-pot three-component sequential synthetic protocol produces structurally and biologically important phthalidyl fused spiro N,N′-disubstituted thiohydantoins from readily available aromatic isothiocyanates, primary amines and ninhydrin. In this three-step synthesis while the initial two steps are catalyst-free, in the final step silica sulfuric acid (SSA) induces an oxidative rearrangement in [3.3.0]-bicyclic 1,2-diol adducts of ninhydrin and thioureas under solvent-free condition to generate the final products spiro-fused thiohydantoins. The adequate acidity of SSA in cooperation with moderate oxidizing property promotes a facile oxidative rearrangement in 1,2-diol intermediates to produce the spiro-fused thiohydantoins with diverse functionalities. Easy recyclability of SSA, good to excellent yield of the products, wider substrate scope, shorter reaction time, solvent-free two steps out of three and high atom economy make this method attractive and practicable.
- Mandal, Subhro,Pramanik, Animesh
-
-
- Dual palladium-photoredox catalyzed chemoselective C-H arylation of phenylureas
-
A highly chemoselective C-H arylation of phenylureas has been accomplished using dual palladium-photoredox catalysis at room temperature without any additives, base or external oxidants. Regioselective C-H arylation ofN,N'-diaryl substituted unsymmetrical phenylureas has also been accomplished by a careful choice of aryl groups.
- Babu, Sakamuri Sarath,Shahid,Gopinath, Purushothaman
-
supporting information
p. 5985 - 5988
(2020/06/04)
-
- 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
-
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 0187-0190
(2019/06/07)
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- Biochemical and microbiological evaluation of: N-aryl urea derivatives against mycobacteria and mycobacterial hydrolases
-
A focused library of 24 N-aryl urea derivatives was prepared and evaluated against serine esterases of Mycobacterium tuberculosis (Mtb) Rv3802c and Mtb Ag85C. The members of the library were evaluated for both selectivity and mode of inhibition. Furan-bas
- Vartak, Abhishek,Goins, Christopher,De Moura, Vinicius Calado Nogueira,Schreidah, Celine M.,Landgraf, Alexander D.,Lin, Boren,Du, Jianyang,Jackson, Mary,Ronning, Donald R.,Sucheck, Steven J.
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p. 1197 - 1204
(2019/07/25)
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- Pd/C-Catalyzed Domino Synthesis of Urea Derivatives Using Chloroform as the Carbon Monoxide Source in Water
-
A Pd/C-catalyzed domino synthesis of symmetrical and unsymmetrical ureas from aryl iodides, sodium azide, amines and CHCl3 in water has been developed. This reaction proceeds with sequential carbonylation, Curtius rearrangement and nucleophilic addition. CHCl3 serves as a convenient and safe alternation of CO gas in the presence of KOH. A series of urea derivatives were obtained in moderate to good yields with good functional group tolerance. Furthermore, the Pd/C catalyst could be readily recovered with slight decrease in the catalytic activity after six consecutive runs. (Figure presented.).
- Wang, Liang,Wang, Hao,Li, Guiqing,Min, Shuliang,Xiang, Fangyuan,Liu, Shiqi,Zheng, Waigang
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p. 4585 - 4593
(2018/10/31)
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- Chemoselective isocyanide insertion into the N-H bond using iodine-DMSO: Metal-free access to substituted ureas
-
Insertion of isocyanides into the N-H bond gives access to many medicinally important and structurally diverse complex nitrogen-containing heterocycles. Although the transition metal catalyzed isocyanide insertion into the N-H bond is very common, polymerization of isocyanides in the presence of a transition metal and their strong coordination with metals are the common drawbacks. On the other hand, the inertness of most of the isocyanides towards amines in the absence of a metal catalyst has stymied the growth of the metal-free approach for isocyanide insertion into amines. As a result, only a handful of metal catalysed methods with limited substrate scopes have been reported for the synthesis of ureas via isocyanide insertion into amines and no metal-free version has been reported yet. Interestingly, chemoselective isocyanide insertion into amines has not been reported in the literature. We employed the I2-DMSO reagent system for the chemoselective synthesis of ureas, where isocyanides react with aliphatic amines only, while aromatic amines need a nucleophilic activator (DABCO) to facilitate the formation of ureas. This method gave direct and chemoselective access to ureas by evading the commonly used yet toxic isocyanates.
- Bora, Porag,Bez, Ghanashyam
-
supporting information
p. 8363 - 8366
(2018/08/03)
-
- Chloromethylated polystyrene immobilized ruthenium complex of 2-(2-pyridyl)benzimidazole catalyst for the synthesis of bioactive disubstituted ureas by carbonylation reaction
-
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
-
p. 9168 - 9176
(2018/06/08)
-
- 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
-
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
-
-
- 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
-
p. 168 - 176
(2017/01/14)
-
- Alkyl Isocyanates via Manganese-Catalyzed C-H Activation for the Preparation of Substituted Ureas
-
Organic isocyanates are versatile intermediates that provide access to a wide range of functionalities. In this work, we have developed the first synthetic method for preparing aliphatic isocyanates via direct C-H activation. This method proceeds efficiently at room temperature and can be applied to functionalize secondary, tertiary, and benzylic C-H bonds with good yields and functional group compatibility. Moreover, the isocyanate products can be readily converted to substituted ureas without isolation, demonstrating the synthetic potential of the method. To study the reaction mechanism, we have synthesized and characterized a rare MnIV-NCO intermediate and demonstrated its ability to transfer the isocyanate moiety to alkyl radicals. Using EPR spectroscopy, we have directly observed a MnIV intermediate under catalytic conditions. Isocyanation of celestolide with a chiral manganese salen catalyst followed by trapping with aniline afforded the urea product in 51% enantiomeric excess. This represents the only example of an asymmetric synthesis of an organic urea via C-H activation. When combined with our DFT calculations, these results clearly demonstrate that the C-NCO bond was formed through capture of a substrate radical by a MnIV-NCO intermediate.
- Huang, Xiongyi,Zhuang, Thompson,Kates, Patrick A.,Gao, Hongxin,Chen, Xinyi,Groves, John T.
-
supporting information
p. 15407 - 15413
(2017/11/06)
-
- Oximes as reusable templates for the synthesis of ureas and carbamates by an: In situ generation of carbamoyl oximes
-
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
-
supporting information
p. 4272 - 4277
(2017/09/28)
-
- Urea anions: Simple, fast, and selective catalysts for ring-opening polymerizations
-
Aliphatic polyesters and polycarbonates are a class of biorenewable, biocompatible, and biodegradable materials. One of the most powerful methods for accessing these materials is the ring-opening polymerization (ROP) of cyclic monomers. Here we report that the deprotonation of ureas generates a class of versatile catalysts that are simultaneously fast and selective for the living ring-opening polymerization of several common monomers, including lactide, δ-valerolactone, ε-caprolactone, a cyclic carbonate, and a cyclic phosphoester. Spanning several orders of magnitude, the reactivities of several diaryl urea anions correlated to the electron-withdrawing substituents on the aryl rings. With the appropriate urea anions, the polymerizations reached high conversions (~90%) at room temperature within seconds (1-12 s), yielding polymers with narrow molecular weight distributions (Crossed D sign = 1.06 to 1.14). These versatile catalysts are simple to prepare, easy to use, and exhibit a range of activities that can be tuned for the optimal performance of a broad range of monomers. (Chemical Equation Presented).
- Lin, Binhong,Waymouth, Robert M.
-
supporting information
p. 1645 - 1652
(2017/02/10)
-
- A facile method for the preparation of unsymmetrical ureas utilizing zirconium (IV) chloride
-
A facile synthetic method for the preparation of unsymmetrical ureas from amines is described. Carbamoyl imidazole compounds were prepared by the reaction of 1, 1-carbonyldiimidazole with primary or secondary amines, and further activation by treatment with zirconium(IV) chloride to generate the desired urea. This reaction protocol was applied to the synthesis of tri and tetrasubstituted ureas with high yields. This study provides an alternative guideline for the practical preparation of various unsymmetrical ureas.
- Lee, Anna,Kim, Hee-Kwon,Thompson, David H.
-
p. 154 - 160
(2016/02/26)
-
- Ethyl 2-cyano-2-(4-nitrophenylsulfonyloxyimino)acetate-mediated lossen rearrangement: Single-pot racemization-free synthesis of hydroxamic acids and ureas from carboxylic acids
-
Ethyl 2-cyano-2-(4-nitrophenylsulfonyloxyimino)acetate (4-NBsOXY) mediated Lossen rearrangement and its application for the synthesis of ureas is demonstrated. Required hydroxamic acids for the Lossen rearrangements were synthesized from carboxylic acids using the same reagent. Finally, reaction of an amine with the produced isocyanate resulted in urea. Good yields without racemization were achieved under milder and simpler reaction conditions. Reactions are compatible with common N-protecting groups, such as Boc, Fmoc, Cbz, and benzyl, as well as various OH protecting groups, such as tBu and Bzl. Conversion from carboxylic acid to urea is achieved in one pot. Most importantly, byproducts Oxyma [ethyl 2-cyano-2-(hydroxyimino)acetate] and 4-nitrobenzenesulfonic acid can be recovered easily and can be recycled to prepare the reagent. Thus, the method is environmentally friendly and cost-effective.
- Thalluri, Kishore,Manne, Srinivasa Rao,Dev, Dharm,Mandal, Bhubaneswar
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p. 3765 - 3775
(2014/05/20)
-
- Polystyrene anchored ruthenium(II) complex catalyzed carbonylation of nitrobenzene and amines for the synthesis of disubstituted ureas
-
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)
-
- Polystyrene anchored ruthenium(II) complex catalyzed carbonylation of nitrobenzene and amines for the synthesis of disubstituted ureas
-
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)
-
- Bromodimethylsulfonium bromide (BDMS)-mediated Lossen rearrangement: Synthesis of unsymmetrical ureas
-
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.
-
experimental part
p. 2890 - 2893
(2012/07/27)
-
- Palladium-catalyzed cross-coupling of aryl chlorides and triflates with sodium cyanate: A practical synthesis of unsymmetrical ureas
-
An efficient method for palladium-catalyzed cross-coupling of aryl chlorides and triflates with sodium cyanate is reported. The protocol allows for the synthesis of unsymmetrical N,N'-di- and N,N,N'-trisubstituted ureas in one pot and is tolerant of a wide range of functional groups. Insight into the mechanism of aryl isocyanate formation was gleaned through studies of the transmetalation and reductive elimination steps of the reaction, including the first demonstration of reductive elimination from an arylpalladium isocyanate complex to produce an aryl isocyanate.
- Vinogradova, Ekaterina V.,Fors, Brett P.,Buchwald, Stephen L.
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p. 11132 - 11135
(2012/08/28)
-
- Highly efficient synthesis of ureas and carbamates from amides by iodosylbenzene-induced hofmann rearrangement
-
A simple and efficient method for the synthesis of 1,3-disubstituted ureas and carbamates from amides by using iodosylbenzene as the oxidant is described. Symmetric and asymmetric ureas and carbamates can be prepared by this procedure in up to 98 % yield. Ureidopeptides can also be prepared in good yield by this method. A simple and efficient method for the synthesis of 1,3-disubstituted ureas and carbamates from amides by using iodosylbenzene as the oxidant is described. By using this method, heterocyclic products can be easily obtained in excellent yield. Ureidopeptides can also be prepared in good yield by this procedure. Copyright
- Liu, Peng,Wang, Zhiming,Hu, Xianming
-
experimental part
p. 1994 - 2000
(2012/05/05)
-
- Synthesis of urea derivatives from amines and CO2 in the absence of catalyst and solvent
-
Urea derivatives are obtained in mild to good yield from the reactions of primary aliphatic amines with CO2 in the absence of any catalysts, organic solvents or other additives. To optimize reaction conditions, experimental variables including temperature, pressure, the concentration of amine, reaction time etc. were studied. Satisfactory yields were obtained at the optimized conditions that are comparable to the presence of catalyst and solvent. The preliminary investigation of the reaction mechanism showed that alkyl ammonium alkyl carbamate was quickly formed as the intermediate, and then the final product was formed by the intramolecular dehydration.
- Wu, Chaoyong,Cheng, Haiyang,Liu, Ruixia,Wang, Qiang,Hao, Yufen,Yu, Yancun,Zhao, Fengyu
-
scheme or table
p. 1811 - 1816
(2011/02/22)
-
- Cyanuric chloride: an efficient reagent for the Lossen rearrangement
-
An efficient method for the Lossen rearrangement that uses 2,4,6-trichloro-1,3,5-triazine (TCT) as a promoter is reported. This procedure allowed the preparation of various carbamates, thiocarbamates, and ureas in good yields directly from the correspondi
- Hamon, Florian,Prié, Gildas,Lecornué, Frédéric,Papot, Sébastien
-
experimental part
p. 6800 - 6802
(2010/04/27)
-
- Phenyl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylate as carbonyl source: Facile and selective synthesis of carbamates and ureas under mild conditions
-
The selective syntheses of carbamates, symmetric -ureas, and unsymmetrical ureas have been accomplished by the -reaction of amines with phenyl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylate as a carbonyl source under mild conditions. It is noteworthy that this process is mild, economic, and convenient.
- Lee, Hyung-Geun,Kim, Min-Jung,Park, Song-Eun,Kim, Jeum-Jong,Kim, Bo Ram,Lee, Sang-Gyeong,Yoon, Yong-Jin
-
experimental part
p. 2809 - 2814
(2010/03/03)
-
- A general method for the synthesis of unsymmetrically substituted ureas via palladium-catalyzed amidation
-
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.
-
supporting information; experimental part
p. 947 - 950
(2009/08/07)
-
- Multicomponent, one-pot sequential synthesis of 1,3,5- and 1,3,5,5-substituted barbiturates
-
(Chemical Equation Presented) Carbodiimides and malonic acid monoethylesters readily react to afford N-acylurea derivatives that could be cyclized in situ by addition of a suitable base. This process represents a general and straightforward one-pot sequential synthesis of 1,3,5-trisubstituted barbiturates in very mild conditions (organic solvent/2 N NaOH aqueous solution, 20°C). Performing the reaction in the presence of an electrophile resulted in the formation of fully substituted (namely, 1,3,5,5- tetrasubstituted) barbiturates through a three-component one-pot sequential process. The latter, however, occurred only with highly reactive electrophiles, such as benzyl and, in some instances, allyl halides. In order to expand the scope of the process, we sought to develop a general method for the C-alkylation of 1,3,5-trisubstituted barbiturates. We found that C-alkylation occurred upon treatment of 1,3,5-trisubstituted barbiturates with an alkyl halide in CH 3CN at 120°C in the presence of anhydrous K2CO 3 affording the target 1,3,5,5-tetrasubstituted barbiturates in good yields. The multicomponent process was accomplished by combining the three steps in a one-pot sequential fashion, i.e., the condensation of carbodiimides with malonic acid monoethylesters, the cyclization of the resulting N-acylureas, and the C-alkylation of the resulting 1,3,5-substituted barbiturates. A detailed study of the influence of the structure of the reactants on the reaction outcome and mechanism is presented. By selective N′-deprotection of 1,3,5,5-tetrasubstituted barbiturates, the corresponding 1,5,5-trisubstituted barbiturates were also prepared.
- Volonterio, Alessandro,Zanda, Matteo
-
p. 7486 - 7497
(2008/12/22)
-
- Thiol on silica as a 'catch and release' support for isocyanates to afford ureas
-
Silica-bound thiocarbamates were prepared by Curtius rearrangement of carboxylic acids in the presence of thiol on silica gel. The solid supported thiocarbamates were found to be stable isocyanate equivalents, which upon treatment with amines efficiently afforded di- and tri-substituted ureas. The urea products released from the catch and release support were, in the majority of cases, greater than 95% pure and required no further work up.
- Bolshan, Yuri,Tomaszewski, Miroslaw J.,Santhakumar, Vijayaratnam
-
p. 4925 - 4927
(2008/02/08)
-
- A new practical method for the synthesis of unsymmetrical ureas via high-pressure-promoted condensation of 2,2,2-trichloroethyl carbamates (Troc-carbamates) with amines
-
A new practical method for the synthesis of unsymmetrical ureas was achieved by condensation between 2,2,2-trichloroethyl carbamates (Troc-carbamates) and primary or secondary amines under high-pressure conditions.
- Azad, Saleha,Kumamoto, Koji,Uegaki, Kaoru,Ichikawa, Yoshiyasu,Kotsuki, Hiyoshizo
-
p. 587 - 590
(2007/10/03)
-
- Synthetic studies toward aryl-(4-aryl-4H-[1,2,4]triazole-3-yl)-amine from 1,3-diarylthiourea as urea mimetics
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A thiophile-promoted synthesis of disubstituted 4H-[1,2,4]triazole-3-yl- amines as urea mimetics from the corresponding 1,3-disubstituted thioureas has been studied, and the scope and limitations of this reaction are presented. The reaction proceeds through the formation of a carbodiimide, followed by a sequential addition-dehydration with acyl hydrazides. 1,3-Branched dialkylthioureas result in the formation of the corresponding ureas. The electronic and steric effects of the substitution on the phenyl rings of the 1,3-diarylthioureas play an important role in the formation of the intermediary carbodiimde and the direction of the subsequent ring closure of the N-acyl hydrazide adduct.
- Natarajan, Amarnath,Guo, Yuhong,Arthanari, Haribabu,Wagner, Gerhard,Halperin, Jose A.,Chorev, Michael
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p. 6362 - 6368
(2007/10/03)
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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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- 1,2,3- and 1,2,4-triazolium salts, pyrazoles, and quinoxalines from diarylnitrilimines and isocyanides: A study of the scope
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Formation of the four title compounds has been found to be strongly dependent on substituents: 1,2,3-Triazolium salts 6 do not arise from nitrilimines 2 that have an electron- acceptor attached to either the C- or the N-phenyl group. Likewise tert-butyl and aryl isocyanides do not afford this class of compounds; from the former isocyanide, dequaternization products 7 are obtained instead, whereas from the latter 1,2,4-triazolium salts 11 are formed. Compounds 11 with a tert-butyl group at the ring are unstable too, giving rise to triazoles 13. Pyrazole formation (analogues of 14) is completely suppressed when both tert-butyl and aryl isocyanides are used, whereas access to this ring system works best with sec-alkyl isocyanides (the influence of substituents of 2 being almost negligible in this case). Formation of quinoxalines 23 which arise from intermediary 1,2-diazets 22 by ring expansion is much favoured on employment of 2 that bears a donator substituent at the N-phenyl group, and under this premise ring closure to 22 is virtually independent on the nature of the isocyanide. Formation of 23 is not observed with 2 having acceptor groups.
- Moderhack, Dietrich,Daoud, Ali
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p. 625 - 637
(2007/10/03)
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- Structural refinement of inhibitors of urea-based soluble epoxide hydrolases
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The soluble epoxide hydrolase (sEH) is involved in the metabolism of arachidonic, linoleic, and other fatty acid epoxides, endogenous chemical mediators that play an important role in blood pressure regulation and inflammation. 1,3-Disubstituted ureas, carbamates, and amides are new potent and stable inhibitors of sEH. However, the poor solubility of the lead compounds limits their use. Inhibitor structure-activity relationships were investigated to better define the structural requirements for inhibition and to identify points in the molecular topography that could accept polar groups without diminishing inhibition potency. Results indicate that lipophilicity is an important factor controlling inhibitor potency. Polar groups could be incorporated into one of the alkyl groups without loss of activity if they were placed at a sufficient distance from the urea function. The resulting compounds had a 2-fold higher water solubility. These findings will facilitate the rational design and optimization of sEH inhibitors with better physical properties.
- Morisseau, Christophe,Goodrow, Marvin H.,Newman, John W.,Wheelock, Craig E.,Dowdy, Deanna L.,Hammock, Bruce D.
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p. 1599 - 1608
(2007/10/03)
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- Novel substituted 4-aminomethylpiperidines as potent and selective human β3-agonists. Part 1: Aryloxypropanolaminomethylpiperidines
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The synthesis and SAR of a series of human β3 adrenoreceptor agonists based on a template derived from a common pharmacophore coupled with 4-aminomethylpiperidine is described. Potent and selective agents were identified such as 26 that was in vitro active in CHO cells expressing human β3-AR (EC50=49 nM, IA=1.1), and in vivo active in a transgenic mouse model.
- Steffan, Robert J.,Ashwell, Mark A.,Solvibile, William R.,Matelan, Edward,Largis, Elwood,Han, Stella,Tillet, Jeffery,Mulvey, Ruth
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p. 2957 - 2961
(2007/10/03)
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- A novel ZrO2-SO42- supported palladium catalyst for syntheses of disubstituted ureas from amines by oxidative carbonylation
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The syntheses of disubstituted ureas by carbonylation of a series of amines in the presence of a sulfate modified zirconia supported palladium catalyst was investigated at an initial total pressure of 4.0 MPa and 135°C. High conversions and yields were achieved for the synthesis of symmetric dialkylureas. This supported catalyst could also be easily separated and recovered after reaction.
- Shi, Feng,Deng, Youquan,SiMa, Tianlong,Yang, Hongzhou
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p. 2161 - 2163
(2007/10/03)
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- 3-D QSAR analysis of inhibition of murine soluble epoxide hydrolase (MsEH) by benzoylureas, arylureas, and their analogues
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Two hundred and seventy-one compounds including benzoylureas, arylureas and related compounds were assayed using recombinant murine soluble epoxide hydrolase (MsEH) produced from a baculovirus expression system. Among all the insect growth regulators assayed, 18 benzoylphenylurea congeners showed weak activity against MsEH. Newly synthesized cyclohexylphenylurea, 1-benzyl-3-phenylurea, and 1,3-dibenzylurea analogues were rather potent. The introduction of a methyl group at the para-position of the phenyl ring of cyclohexylphenylurea enhanced the activity 6-fold, though similar substituent effects were not seen for any of the benzoylphenylureas. The activities of these compounds, including several previously reported compounds, such as dicyclohexylurea, diphenylurea, and their related analogues (Morisseau et al., Proc. Natl. Acad. Sci., 1999, 96, 8849), were quantitatively analyzed using comparative molecular field analysis (CoMFA), a three-dimensional quantitative structure-activity relationship (3-D QSAR) method. Both steric and electrostatic factors contributing to variations in the activity were visualized using CoMFA. CoMFA results showed that one side of the cyclohexylurea moiety having a trans-amide conformation (A-ring moiety) is surrounded by large sterically unfavorable fields, while the other side of A-ring moiety and the other cyclohexyl group (B-ring moiety) is encompassed by sterically favored fields. Electrostatically negative fields were scattered around the entire molecule, and a positive field surrounds the carbon of the carbonyl group. Hydrophobic fields were visualized using Kellogg's hydropathic interaction (HINT) in conjunction with CoMFA. Hydrophobically favorable fields appeared beside the 4- and 4'-carbon atoms of the cyclohexyl groups, and hydrophobically unfavorable fields surrounded the urea bridge. The addition of the molecular hydrophobicity, it> /it>, to CoMFA did not improve the correlation significantly. The ligand-binding interactions shown by X-ray crystallographic data were rationalized using the results of the CoMFA and HINT analyses, and the essential physicochemical parameters for the design of new MsEH inhibitors were disclosed. Copyright (C) 2000 Elsevier Science Ltd.
- Nakagawa, Yoshiaki,Wheelock, Craig E.,Morisseau, Christophe,Goodrow, Marvin H.,Hammock, Bruce G.,Hammock, Bruce D.
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p. 2663 - 2673
(2007/10/03)
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- 2-chloro-1,3-dimethylimidazolinium chloride. 3. Utility for chlorination, oxidation, reduction, and rearrangement reactions
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2-Chloro-1,3-dimethylimidazolinium chloride (1), which can act as a powerful dehydrating equivalent to DCC (2), is also applicable to chlorination, oxidation, reduction, and rearrangement under nearly neutral conditions. The utility of 1 for these reactions is described.
- Isobe, Toshio,Ishikawa, Tsutomu
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p. 5832 - 5835
(2007/10/03)
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- Selenium-catalyzed reductive carbonylation of nitrobenzene with amines as coreagents to give unsymmetric phenylureas
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The reductive carbonylation of nitrobenzene catalyzed by selenium to yield unsymmetric phenylureas has been studied. When secondary amines were used as coreagents, a single product, PhNHCONR2, was formed; when primary amines were chosen as coreagents, mixed products, including RNHCONHR, RNHCONHPh and PhNHCONHPh, were obtained.
- Yang, Ying,Lu, Shiwei
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p. 4845 - 4846
(2007/10/03)
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- New synthetic strategy for urea herbicides
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This work describes an effective and a safe procedure for the preparation of commercially applicable trisubstituted ureas derived from their thio analogues which result from the thiuram disulfides in quantitative yields.
- Ramadas,Janarthanan
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p. 2357 - 2362
(2007/10/03)
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- A New Convenient Method for the Synthesis of Symmetrical and Unsymmetrical N,N'-Disubstituted Ureas
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A new method is described for the preparation of symmetrically and unsymmetrically disubstituted ureas by aminolysis of bis(4-nitrophenyl) carbonate.The second substitution is slower than the first one, and it is possible to isolate monosubstituted intermediates when equimolar amounts of substrates are used.The reaction of the intermediates with different amines give unsymmetrical derivatives of urea.
- Izdebski, Jan,Pawlak, Danuta
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p. 423 - 425
(2007/10/02)
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- Ureas from Lossen Rearrangements of Hydroxamic Acids Induced by p-Toluenesulfonyl Chloride or 2-Chloro-1-methylpyridinium Iodide in the Presence of Amines: A Correction
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Hydroxamic acids reacted with amines in the presence of either p-toluenesulfonyl chloride or 2-chloro-1-methylpyridinium iodide to produce compounds whose structures are different from those which had been reported.These reactive halides converted hydroxamic acids first to Lossen-type of intermediates, which rearranged spontaneously in basic media to isocyanates which reacted further.In the absence of primary or secondary amines in the medium, the intermediate isocyanates acylated the starting hydroxamic acids to form O-carbamyl hydroxamic acids.However, when the reaction mixtures contained either primary or secondary amines, addition to the intermediate isocyanates provided ureas.Furthermore, it was found that amines caused the O-carbamyl hydroxamic acids to undergo facile Lossen degradations to furnish ureas.
- Pihuleac, Justin,Bauer, Ludwig
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- NOVEL DESULFURIZATION OF THIOCARBONYL COMPOUNDS INTO THEIR CORRESPONDING OXO-DERIVATIVES USING A PEROXY-SULFUR INTERMEDIATE GENERATED FROM 2-NITROBENZENESULFONYL CHLORIDE AND SUPEROXIDE ANION.
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Thiocarbonyl compounds such as substituted-thioureas, -thioamides, and -thiocarbamates were found to react with a peroxysulfur intermediate (3) which is generated by the treatment of 2-nitrobenzenesulfonyl chloride with potassium superoxide to convert into the corresponding carbonyl compounds in quantitative yield at -30 oC in acetonitrile.
- Kim, Yong Hae,Chung, Bong Chul,Chang, Hae Sung
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p. 1079 - 1082
(2007/10/02)
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- Process for preparing substituted urea derivatives
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A process for the preparation of substituted urea derivatives, and compositions and concentrates for the same purpose are disclosed. According to the process the substituted urea derivatives of formula (I) STR1 wherein R is hydrogen, alkyl, aryl, cycloalkyl or aralkyl, R1 and R2 are hydrogen, alkyl, alkenyl, alkinyl, alkoxy, oxyalkyl, cycloalkyl, aralkyl, alkoxycarbonylalkyl, aryl or heteroaryl, or R1 and R2 together with the adjacent nitrogen atom may form a saturated or unsaturated heterocycle, or a condensed and/or substituted ring system, and said heterocycle or said condensed and/or substituted ring system may contain also a sulfo group, can be manufactured by reacting an amine of formula (II) STR2 with an N-carbamoyl-benzoic acid sulfimide derivative of formula (III) STR3 The disclosed N-acylating composition comprises of from 3 to 60% by weight, preferably of from 5 to 50% by weight sulfimide derivative of formula (III), of from 97 to 40% by weight, preferably of from 95 to 50% by weight solvent, and if desired, an organic or inorganic base. The disclosed N-acylating concentrate comprises of from 60 to 95.5% by weight N-acylating agent of formula (III) and of from 4.5 to 40% by weight additives.
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