- Curtius-like Rearrangement of an Iron-Nitrenoid Complex and Application in Biomimetic Synthesis of Bisindolylmethanes
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A Curtius-like rearrangement of hydroxamates to isocyanates was discovered. This reaction was initiated from an iron(II)-nitrenoid complex, which was generated by the iron(II)-catalyzed cleavage of N-O bonds of functionalized hydroxamates. To demonstrate the efficiency of this new Curtius-like rearrangement in synthetic chemistry, a biomimetic strategy for the one-pot preparation of bisindolylmethanes was developed.
- Li, Dashan,Wu, Ting,Liang, Kangjiang,Xia, Chengfeng
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- 2,2,2-Trifluroenthanol promoted synthesis of unsymmetrical ureas from dioxazolones and amines via tandem lossen rearrangement/condensation process
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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
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supporting information
p. 3590 - 3600
(2021/10/07)
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- Broad Scope and High-Yield Access to Unsymmetrical Acyclic [11C]Ureas for Biomedical Imaging from [11C]Carbonyl Difluoride
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Effective methods are needed for labelling acyclic ureas with carbon-11 (t1/2=20.4 min) as potential radiotracers for biomedical imaging with positron emission tomography (PET). Herein, we describe the rapid and high-yield syntheses of unsymmet
- Jakobsson, Jimmy E.,Jana, Susovan,Lu, Shuiyu,Pike, Victor W.,Telu, Sanjay
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supporting information
p. 10369 - 10376
(2021/06/07)
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- Stabilization of the hindered urea bond through de-tert-butylation
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We report the discovery of an acid-assisted de-tert-butylation reaction that can instantly “turn off” the dynamicity of hindered urea bonds (HUBs) and thus broaden their applications. The reaction is demonstrated to be widely applicable to different hindered urea substrates, leading to improved chemical stabilities and mechanical properties of HUB-containing materials.
- Yang, Yingfeng,Ying, Hanze,Jia, Yunchao,Chen, Yingying,Cheng, Jianjun
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supporting information
p. 3812 - 3815
(2021/04/21)
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- Synthesis method of substituted urea compound
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The invention discloses a synthesis method of a substituted urea compound, which comprises the following steps: stirring aldehyde, N-aryl urea, trichlorosilane and Lewis base in an organic solvent ata temperature range of -20 DEG C to room temperature for
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Paragraph 0034-0039
(2021/03/31)
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- Lanthanum(III) Trifluoromethanesulfonate Catalyzed Direct Synthesis of Ureas from N-Benzyloxycarbonyl-, N -Allyloxycarbonyl-, and N -2,2,2-Trichloroethoxycarbonyl-Protected Amines
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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
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supporting information
p. 997 - 1002
(2020/06/17)
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- Photocatalyzed synthesis of unsymmetrical ureas via the oxidative decarboxylation of oxamic acids with PANI-g-C3N4-TiO2 composite under visible light
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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
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supporting information
(2020/04/28)
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- Preparation method of amide derivative
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The invention provides a preparation method of an amide derivative. The method comprises the following steps: taking hydroxamic acid and an amine or thiol compound as raw materials, sequentially adding alkali and a solvent, carrying out a reaction for 2-7 hours at the temperature of 25-50 DEG C in an SO2F2 atmosphere, and after the reaction is finished, carrying out aftertreatment on a reaction solution to obtain the asymmetric urea compound or thiocarbamate compound. According to the invention, cheap, easily available and environment-friendly SO2F2 is used as an accelerant to efficiently promote the generation of isocyanate intermediates and form C-N and C-S bonds. The generation of isocyanate avoids the use of a large amount of halogen or azide dangerous reagents, so that the compound can be used as a green substitute for standard treatment conditions in Curtius rearrangement and Hofmann rearrangement reactions. The substrate is wide in applicability, and the corresponding asymmetricurea and thiocarbamate compounds can be obtained at a relatively good yield. The operation process is simple and suitable for large-scale preparation.
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Paragraph 0025-0029
(2020/05/30)
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- METHOD OF CONVERTING CARBON DIOXIDE INTO CARBONYL COMPOUNDS
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The present invention provides a method for fixing carbon dioxide gas as a carbonyl compound represented by formula (3) as depicted by Figure 1 and comprising, purging of carbon dioxide in a solution of a nucleophile represented by the formula (1) in presence of a solvent at a temperature ranging from -40 Degree Celsius to 35 Degree Celsius, followed by adding a reagent at temperature ranging from -40 degree to 35 degree and thereafter adding another nucleophile represented by the formula (2) to obtain carbonyl compound represented by formula (3). The present invention can be advantageously used to obtain commercially important carbonyl compounds and clean unwanted carbon dioxide gas from the atmosphere and industrial effluents.
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Page/Page column 14; 15
(2019/05/02)
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- CaI2-Catalyzed direct transformation of: N -Alloc-, N -Troc-, and N -Cbz-protected amines to asymmetrical ureas
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A novel and facile CaI2-catalyzed direct synthesis of asymmetrical ureas from N-Alloc-, N-Troc-, and N-Cbz-protected amines is developed. In this study, the efficient reaction of Alloc-, Troc-, and Cbz-carbamates with amines in the presence of catalytic CaI2 successfully generated various asymmetrical ureas. This catalytic synthetic procedure provided the desired ureas via reactions of these protected aromatic and aliphatic amines with various amines in high yields without side products. This suggests that novel direct synthesis of ureas from Alloc-, Troc-, and Cbz-carbamates can be a promising approach for the synthesis of useful ureas.
- Tran, Van Hieu,Kim, Hee-Kwon
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p. 14093 - 14101
(2019/09/18)
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- A Fe3O4?SiO2/Schiff Base/Pd Complex as an Efficient Heterogeneous and Recyclable Nanocatalyst for One-Pot Domino Synthesis of Carbamates and Unsymmetrical Ureas
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A palladium-catalyzed domino method for the direct synthesis of carbamates and ureas has been developed by using readily available and economical starting materials (aryl halide, carbon monoxide, sodium azide, amines and alcohols) in a one-pot approach. The domino process underwent carbonylation, Curtius rearrangement, and nucleophilic addition. This protocol provides a step-economical and highly efficient reaction to access the wide range of valuable carbamates, symmetrical and unsymmetrical ureas with high yields under remarkable mild reaction conditions that are important factors in pharmaceutical science, biochemistry and agricultural industries. Furthermore, the magnetically recoverable nanocatalyst (Fe3O4?SiO2/Pd(II)) can be conveniently and swiftly recycled using external magnet and reused at least for seven times without noticeable loss of its catalytic activity.
- Inaloo, Iman Dindarloo,Majnooni, Sahar
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p. 6359 - 6368
(2019/11/05)
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- Palladium-Catalyzed Synthesis of Symmetrical and Unsymmetrical Ureas Using Chromium Hexacarbonyl as a Convenient and Safe Alternative Carbonyl Source
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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
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supporting information
p. 7541 - 7544
(2019/12/12)
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- 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.
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Paragraph 0143-0146
(2019/06/07)
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- Pd-Catalyzed Carbonylation of Acyl Azides
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Pd-catalyzed reactions of azides with CO to access an isocynate intermediate have been developed extensively in recent years. However, the catalytic carbonylation of sensitive acyl azides has not been reported. Herein, we report a simple Pd-catalyzed carbonylation reaction of acyl azides with broad substrate scope, high efficiency, and simple operation under mild conditions, which provides facile access to acyl ureas. In addition, a mechanistic study was carried out by both experiment and DFT calculation. Control experiments and kinetic study revealed that the real active palladium species were Pd(0). The result of kinetic study suggested that palladium catalyst, azide, and CO were all involved in the turnover-limiting step except for amine. Further DFT study suggested that an unprecedented five-membered palladacycle intermediate was the key intermediate in the carbonylation reaction. ?
- Chang, Wenxu,Fu, Bin,Huang, Baoliang,Jiao, Lei,Li, Zongyang,Wang, Peng,Xu, Shiyang,Yuan, Chenhui,Zhang, Zhenhua
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p. 9497 - 9508
(2019/08/26)
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- Investigations into the carbonic anhydrase inhibition of COS-releasing donor core motifs
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Carbonyl sulfide (COS) releasing scaffolds are gaining popularity as hydrogen sulfide (H2S) donors through exploitation of the carbonic anhydrase (CA)-mediated hydrolysis of COS to H2S. The majority of compounds in this emerging class of donors undergo triggerable decomposition (often referred to as self-immolation) to release COS, and a handful of different COS-releasing structures have been reported. One benefit of this donation strategy is that numerous caged COS-containing core motifs are possible and are poised for development into self-immolative COS/H2S donors. Because the intermediate release of COS en route to H2S donation requires CA, it is important that the COS donor motifs do not inhibit CA directly. In this work, we investigate the cytotoxicity and CA inhibition properties of different caged COS donor cores, as well as caged CO2 and CS2 motifs and non-self-immolative control compounds. None of the compounds investigated exhibited significant cytotoxicity or enhanced cell proliferation at concentrations up to 100 μM in A549 cells, but we identified four core structures that function as CA inhibitors, thus providing a roadmap for the future development of self-immolative COS/H2S donor motifs.
- Steiger, Andrea K.,Zhao, Yu,Choi, Won Jin,Crammond, Alder,Tillotson, McKinna R.,Pluth, Michael D.
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p. 124 - 130
(2017/12/04)
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- Efficient Direct Halogenation of Unsymmetrical N -Benzyl- and N -Phenylureas with Trihaloisocyanuric Acids
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A simple and efficient methodology for the direct halogenation of N -phenylureas was developed using trihaloisocyanuric acids in acetonitrile at room temperature. This protocol proved to be effective for the construction of N -phenylureas with different patterns of substitution. Additionally, less reactive N -benzylureas were halogenated in the presence of a mixture of trifluoroacetic acid and acetonitrile at room temperature.
- Sanabria, Carlos M.,Costa, Bruno B. S.,Viana, Gil M.,De Aguiar, Lúcia C. S.,De Mattos, Marcio C. S.
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supporting information
p. 1359 - 1367
(2017/12/26)
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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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- Pd/C-Catalyzed Domino Synthesis of Urea Derivatives Using Chloroform as the Carbon Monoxide Source in Water
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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
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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
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supporting information
p. 8363 - 8366
(2018/08/03)
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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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- 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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- 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.
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supporting information
p. 1648 - 1654
(2017/03/21)
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- Pathways in the Degradation of Geminal Diazides
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The degradation of geminal diazides is described. We show that diazido acetates are converted into tetrazoles through the treatment with bases. The reaction of dichloro ketones with azide anions provides acyl azides, through in situ formation of diazido ketones. We present experimental and theoretical evidence that both fragmentations may involve the generation of acyl cyanide intermediates. The controlled degradation of terminal alkynes into amides (by loss of one carbon) or ureas (by loss of two carbons) is also shown.
- Holzschneider, Kristina,H?ring, Andreas P.,Haack, Alexander,Corey, Daniel J.,Benter, Thorsten,Kirsch, Stefan F.
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p. 8242 - 8250
(2017/08/14)
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- KI Catalyzed Nitrogenation of Aldehydes and Alcohols: Direct Synthesis of Carbamoyl Azides and Ureas
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An efficient KI catalyzed nitrogenation of aldehydes and alcohols for the direct synthesis of carbamoyl azides and ureas via a radical process has been developed. The simple operating procedures, the readily available starting materials including aldehydes, alcohols and amines, as well as the utility of the products all make this strategy very attractive.
- Song, Song,Feng, Peng,Zou, Miancheng,Jiao, Ning
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p. 845 - 848
(2017/06/27)
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- Sulfated polyborate-catalyzed efficient and expeditious synthesis of (un)symmetrical ureas and benzimidazolones
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The excellent catalytic potential of sulfated polyborate is utilized in the synthesis of (un)symmetrical ureas and benzimidazolones by heating amines or substituted OPDA and urea or N-phenylureas under a solvent-free condition at 120 °C is described. The key advantages of the present protocol are phosgene-free, and other hazardous reagents or organic solvent free, high reaction rates and yields, simple workup procedure, and recyclability of the catalyst.
- Rekunge, Deelip S.,Khatri, Chetan K.,Chaturbhuj, Ganesh U.
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supporting information
p. 4304 - 4307
(2017/10/12)
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- POLARIZING PLATE COMPOSITION, POLARIZING PLATE PROTECTIVE FILM, POLARIZER, POLARIZING PLATE, LIQUID CRYSTAL DISPLAY DEVICE, AND COMPOUND USED IN THE LIQUID CRYSTAL DISPLAY DEVICE
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Provided are a polarizing plate composition, a polarizing plate protective film, a polarizer, a polarizing plate, and a liquid crystal display device, which contain a compound represented by the following Formula (I), and a compound. In Formula (I), each of R1 and R2 represents a substituent. X represents an electron-withdrawing group, and Y represents a substituent having a heteroatom or a carbon atom as an atom bonded to a carbon atom substituted with —OR1. Y and X may form a ring by being bonded to each other.
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Paragraph 0433
(2017/01/31)
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- A facile method for the preparation of unsymmetrical ureas utilizing zirconium (IV) chloride
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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.
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p. 154 - 160
(2016/02/26)
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- A high-yielding, expeditious, and multicomponent synthesis of urea and carbamate derivatives by using triphenylphosphine/trichloroisocyanuric acid system
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An efficient method for the synthesis of urea and carbamate derivatives from amines and alcohols is described by using triphenylphosphine (PPh3)/trichloroisocyanuric acid system. The protocol allows for the preparation of symmetrical, unsymmetrical di, tri-, and tetra-substituted ureas and carbamates and is tolerant of a wide range of functional groups. To optimize the reaction conditions, experimental variables including temperature, the concentration of amine and alcohol, solvent, and reaction time were studied. Satisfactory yields were obtained at the optimized conditions. The present methodology is experimentally simple, mild, and represents a valuable alternative to the existing methods.
- Ghodsinia, Sara S.E.,Akhlaghinia, Batool
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p. 104 - 110
(2016/01/25)
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- 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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- A synthetic N, N '-di-substituted ureas method
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The invention discloses a method for synthesizing N,N'-disubstituent urea. The method comprises the following steps: adding N-substituent urea, a metal iridium, rhodium or ruthenium complex catalyst, an alkali, a compound alcohol and a solvent (or no solvent) to a reaction container; reacting at 90-130 DEG C for a plurality of hours and cooling the reaction mixture to room temperature; carrying out rotary evaporation to remove the solvent, and then separating through a column, so as to obtain a target compound. Compared with the prior art, N,N'-disubstituent urea which is obtained by regional selective alkylation reaction between commercial or easily synthesized N-substituent urea and the alcohol reflects and displays three significant advantages: 1) the alcohol which is nearly non-toxic is utilized as an alkylating reagent; 2) just water is generated as a by-product in the reaction, and harm to environment is not generated; 3) reaction atom economy is high. Therefore, the reaction accords with the requirements of green chemistry, and has a broad development prospect.
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Paragraph 0025-0028; 0230
(2016/11/17)
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- Facile one-pot synthesis of unsymmetrical ureas, carbamates, and thiocarbamates from Cbz-protected amines
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A novel one-pot synthesis of unsymmetrical ureas, carbamates and thiocarbamates from Cbz-protected amines has been developed. In the presence of 2-chloropyridine and trifluoromethanesulfonyl anhydride, isocyanates are generated in situ, which facilitate rapid reaction with amines, alcohols, and thiols to afford the corresponding ureas, carbamates and thiocarbamates in high yields.
- Kim, Hee-Kwon,Lee, Anna
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supporting information
p. 7345 - 7353
(2016/08/05)
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- Pd/C Catalyzed Carbonylation of Azides in the Presence of Amines
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A facile and efficient Pd/C-catalyzed carbonylation of both aliphatic and aromatic azides in the presence of amines is reported. Serving as the widely existed fragments in an array of biological pharmaceuticals, functionalized unsymmetrical ureas were str
- Zhao, Jin,Li, Zongyang,Yan, Shuaihu,Xu, Shiyang,Wang, Ming-An,Fu, Bin,Zhang, Zhenhua
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supporting information
p. 1736 - 1739
(2016/05/19)
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- Guanidine Synthesis: Use of Amidines as Guanylating Agents
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The use of amidines for the tandem or one-pot synthesis of guanidines is reported. Guanidines are obtained by oxidative rearrangement of readily available and stable amidines into carbodiimides, followed by in situ reaction with amines. The protocol can be executed under mild reaction conditions (30°C), in a green solvent (dimethyl carbonate). The amine scope is broad, including sterically hindered, oxidation-sensitive and chiral amines. Examples for the synthesis of both acyclic and cyclic guanidines are provided. 2-Propoxyphenyl iodide (2-PrOPhI) by-product, generated from the oxidant [N-(p-toluenesulfonyl)imino](2-propoxyphenyl)iodinane (2-PrOPhINTs), can be isolated in high yields making regeneration of the hypervalent iodine reagent possible. The utility and greenness of the synthetic method versus the state-of-the-art is demonstrated by a new route towards the antihypertensive drug Pinacidil. The process mass intensity (PMI) of the new route is only 24% of the classical one.
- Baeten, Mattijs,Maes, Bert U. W.
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p. 826 - 833
(2016/03/12)
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- Preparation method for alkyl/benzyl/aryl urea compounds through heterogeneous-phase catalysis
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The invention discloses a preparation method for formula (I) compounds, and the compounds are obtained by reacting a formula (II) compound with a formula (III) compound in a solvent in carbon monoxide atmosphere under catalysis of a heterogeneous-phase pa
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Paragraph 0063-0071; 0072; 0073; 0074; 0076; 0078; 0084
(2016/10/09)
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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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- Off-rate screening (ORS) by surface plasmon resonance. An efficient method to kinetically sample hit to lead chemical space from unpurified reaction products
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The dissociation rate constant kd (off-rate) is the component of ligand-protein binding with the most significant potential to enhance compound potency. Here we provide theoretical and empirical data to show that this parameter can be determined accurately from unpurified reaction products containing designed test compounds. This screening protocol is amenable to parallel chemistry, provides efficiencies of time and materials, and complements existing methodologies for the hit-to-lead phase in fragment-based drug discovery.
- Murray, James B.,Roughley, Stephen D.,Matassova, Natalia,Brough, Paul A.
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supporting information
p. 2845 - 2850
(2014/05/06)
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- One-pot synthesis of ureas from Boc-protected amines
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A practical one-pot synthesis of ureas is described. Boc-protected amines can be transformed into nonsymmetrical and symmetrical disubstituted and trisubstituted ureas utilizing 2-chloropyridine and trifluoromethanesulfonyl anhydride for the in situ generation of an isocyanate, which reacts with an amine. A variety of amines can be employed successfully, leading to high yields of isolated ureas.
- Spyropoulos, Constantinos,Kokotos, Christoforos G.
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p. 4477 - 4483
(2014/06/09)
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- Ethyl 2-cyano-2-(4-nitrophenylsulfonyloxyimino)acetate-mediated lossen rearrangement: Single-pot racemization-free synthesis of hydroxamic acids and ureas from carboxylic acids
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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)
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- An easy access to unsymmetrical ureas: A photocatalytic approach to the Lossen rearrangement
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An efficient and operationally simple method for the synthesis of unsymmetrical ureas from various hydroxamic acids and amines has been developed. Plausibly, the protocol involves visible-light-initiated in situ formation of Vilsmeier-Haack reagent and COBr2 with CBr4 and a catalytic amount of DMF in the presence of Ru(bpy)3Cl2 as a photocatalyst to bring about the Lossen rearrangement at room temperature. the Partner Organisations 2014.
- Yadav, Arvind K.,Srivastava, Vishnu P.,Yadav, Lal Dhar S.
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p. 24498 - 24503
(2014/07/07)
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- Spectroscopic kinetic study of the interaction of urethanes with amines
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The exchange reactions of phenyl-N-phenylurethane with amines varying in structure and nature have been investigated in o-dichlorobenzene. In the absence of a catalyst and proton-donating compound, the unimolecular decomposition of phenyl-N-phenylurethane into isocyanate and alcohol takes place at a noticeable rate starting at 250°C. The exchange reactions at 60-80°C proceed as a direct exchange between the urethane and the proton donor and are second-order up to high conversions, practically until the disappearance of the entire urethane. The activation energies and apparent rate constants of the exchange reactions of phenyl-N-phenylurethane with various amines have been determined. The results have been explained in terms of the dependence of kinetic parameters of the reaction on the amine nature, structure, and nucleophilicity, on the steric accessibility of the amino group, and on the molecular organization of the solution. Pleiades Publishing, Ltd., 2013.
- Dzalmukhanova,Lodygina,Komratova,Badamshina
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p. 656 - 661
(2014/01/23)
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- An efficient transformation of ethers to N,N′-disubstituted ureas in a Ritter type reaction
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A simple, mild, and an alternative protocol for the preparation of N,N′-disubstituted ureas from readily available ethers and cyanamides as starting materials is described. The protocol explores the reactivity of ether in a Ritter type reaction with cyanamide in the presence of BF 3·Et2O and resulting in the formation of N,N′-disubstituted urea. Divinyl ether as well as MTBE (methyl tert-butyl ether) can be employed as ether components to afford allyl and tert-butyl ureas respectively.
- Panduranga, Veladi,Basavaprabhu,Sureshbabu, Vommina V.
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p. 975 - 979
(2013/04/10)
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- The use of aqueous potassium dichloroiodate for the synthesis of ureas
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We report a straightforward and efficient reaction protocol for the syntheses of substituted ureas via treatment of thioureas with aqueous potassium dichloroiodate (KICl2). By tuning the reaction condition, thioureas bearing activated N-aryl substituents may undergo either selective oxidation or sequential oxidation and iodination, forming iodoaryl ureas in the latter case.
- Viana, Gil Mendes,De Sequeira Aguiar, Lúcia Cruz,De Araújo Ferr?o, Jonas,Simas, Alessandro Bolis Costa,Vasconcelos, Marcela Guariento
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p. 936 - 940
(2013/03/13)
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- One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger-aza-Wittig reaction
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A fast and efficient protocol for the synthesis of N,N'-disubstituted urea derivatives from alkyl halides and primary or secondary amines has been developed. The synthetic pathway combines nucleophilic substitutions and a Staudinger-aza-Wittig reaction in the presence of polymer-bound diphenylphosphine under 14 bar of CO2 pressure and has been performed in a one-pot two-step process. The protocol has been optimized under microwave irradiation and the scale-up experiment has been conducted under conventional conditions in a Parr reactor. The final compounds were isolated after simple filtration in almost quantitative overall yields which makes this procedure facile and rapid to execute.
- Carnaroglio, Diego,Martina, Katia,Palmisano, Giovanni,Penoni, Andrea,Domini, Claudia,Cravotto, Giancarlo
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supporting information
p. 2378 - 2386
(2014/01/06)
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- Iron(III) catalysed synthesis of unsymmetrical di and trisubstituted ureas - A variation of classical Ritter reaction
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An application of the classical Ritter reaction for the synthesis of unsymmetrical di and trisubstituted ureas catalyzed by FeCl3 is described. The protocol is of significant interest in view of the easy availability of precursors, mild reaction conditions employed and interestingly its applicability for the alkylation of alcohols capable of forming stable carbocationic intermediates even to the sterically hindered moieties. The Royal Society of Chemistry 2012.
- Basavaprabhu, Hosamani,Sureshbabu, Vommina V.
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supporting information; experimental part
p. 2528 - 2533
(2012/04/23)
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- Diphenylthiourea, a common rubber chemical, is bioactivated to potent skin sensitizers
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Diphenylthiourea (DPTU) is a known skin sensitizer commonly used as a vulcanization accelerator in the production of synthetic rubber, for example, neoprene. The versatile usage of neoprene is due to the multifaceted properties of the material; for example, it is stretchable, waterproof, and chemical-and abrasion-resistant. The wide application of neoprene has resulted in numerous case reports of dermatitis patients allergic to DPTU. The mechanism by which DPTU works as a contact allergen has not been described; thus, the aim of the present study was to investigate if DPTU is a prohapten that can be activated by skin metabolism. The metabolic activation and covalent binding of 14C-labeled DPTU to proteins were tested using a skinlike cytochrome P450 (P450) cocktail containing the five most abundant P450s found in human skin (CYP1A1, 1B1, 2B6, 2E1, and 3A5) and human liver microsomes. The incubations were carried out in the presence or absence of the metabolite trapping agents glutathione, methoxylamine, and benzylamine. The metabolism mixtures were analyzed by LC-radiochromatography, LC-MS, and LC-MS/MS. DPTU was mainly metabolically activated to reactive sulfoxides resulting in desulfurated adducts in both enzymatic systems used. Also, phenylisothiocyanate and phenylisocyanate were found to be metabolites of DPTU. The sensitizing capacity of the substrate (DPTU) and three metabolites was tested in the murine local lymph node assay. Two out of three metabolites tested were strong skin sensitizers, whereas DPTU itself, as previously known, was negative using this mouse model. In conclusion, DPTU forms highly reactive metabolites upon bioactivation by enzymes present in the skin. These metabolites are able to induce skin sensitization and are probable causes for DPTU allergy. To increase the possibilities of diagnosing contact allergy to DPTU-containing items, we suggest that suitable metabolites of DPTU should be used for screening testing.
- Samuelsson, Kristin,Bergstroem, Moa Andresen,Jonsson, Charlotte A,Westman, Gunnar,Karlberg, Ann-Therese
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experimental part
p. 35 - 44
(2012/01/13)
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- Low molecular weight MPEG-assisted organic synthesis
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A toolkit of low molecular weight MPEG-supported coupling agents ( MIIDQ, MEDCI), reagents for the Mitsunobu reaction ( MDEAD, MTPP), an alternative to diazomethane, and scavengers can be used in the solution-phase synthesis of amides, esters and ureas and are easily removed after use by solid-phase extraction (MSPE) using normal silica.
- Figlus, Marek,Tarruella, Albert C.,Messer, Anastasia,Sollis, Steven L.,Hartley, Richard C.
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supporting information; experimental part
p. 4405 - 4407
(2010/09/15)
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- Parallel synthesis of ureas and carbamates from amines and CO2 under mild conditions
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"Chemical Equation Presented" A mild and efficient library synthesis technique has been developed for the synthesis of ureas and carbamates from carbamic acids derived from the DBU-catalyzed reaction of amines and gaseous carbon dioxide. Carbamic acids derived from primary amines reacted with Mitsunobu reagents to generate isocyanates in situ which were condensed with primary and secondary amines to afford the desired ureas. Similarly, carbamic acids from secondary amines reacted with alcohols activated with Mitsunobu reagents to form carbamates.
- Peterson, Scott L.,Stucka, Sabrina M.,Dinsmore, Christopher J.
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supporting information; experimental part
p. 1340 - 1343
(2010/06/15)
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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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