598-94-7Relevant articles and documents
Green and efficient synthesis of thioureas, ureas, primary: O -thiocarbamates, and carbamates in deep eutectic solvent/catalyst systems using thiourea and urea
Bagherzadeh, Nastaran,Sardarian, Ali Reza,Inaloo, Iman Dindarloo
supporting information, p. 11852 - 11858 (2021/07/12)
An efficient and general catalysis process was developed for the direct preparation of various primary O-thiocarbamates/carbamates as well as monosubstituted thioureas/ureas by using thiourea/urea as biocompatible thiocarbonyl (carbonyl) sources. This procedure used choline chloride/tin(ii) chloride [ChCl][SnCl2]2 with a dual role as a green catalyst and reaction medium to afford the desired products in moderate to excellent yields. Moreover, the DES can be easily recovered and reused for seven cycles with no significant loss in its activity. Besides, the method shows very good performance for synthesizing the desired products on a large scale.
Catalytic hydration of cyanamides with phosphinous acid-based ruthenium(ii) and osmium(ii) complexes: scope and mechanistic insights
álvarez, Daniel,Cadierno, Victorio,Crochet, Pascale,González-Fernández, Rebeca,López, Ramón,Menéndez, M. Isabel
, p. 4084 - 4098 (2020/07/09)
The synthesis of a large variety of ureas R1R2NC(O)NH2 (R1 and R2 = alkyl, aryl or H; 26 examples) was successfully accomplished by hydration of the corresponding cyanamides R1R2NCN using the phosphinous acid-based complexes [MCl2(η6-p-cymene)(PMe2OH)] (M = Ru (1), Os (2)) as catalysts. The reactions proceeded cleanly under mild conditions (40-70 °C), in the absence of any additive, employing low metal loadings (1 molpercent) and water as the sole solvent. In almost all the cases, the osmium complex 2 featured a superior reactivity in comparison to that of its ruthenium counterpart 1. In addition, for both catalysts, the reaction rates observed for the hydration of the cyanamide substrates were remarkably faster than those involving classical aliphatic and aromatic nitriles. Computational studies allowed us to rationalize all these trends. Thus, the calculations indicated that the presence of a nitrogen atom directly linked to the CN bond depopulates electronically the nitrile carbon by inductive effect when coordinated to the metal center, thus favouring the intramolecular nucleophilic attack of the OH group of the phosphinous acid ligand to this carbon. On the other hand, the higher reactivity of Os vs. Ru seems to be related with the lower ring strain on the incipient metallacycle that starts to form in the transition state associated with this key step in the catalytic cycle. Indirect experimental evidence of the generation of the metallacyclic intermediates was obtained by studying the reactivity of [RuCl2(η6-p-cymene)(PMe2OH)] (1) towards dimethylcyanamide in methanol and ethanol. The reactions afforded compounds [RuCl(η6-p-cymene)(PMe2OR)(NCNMe2)][SbF6] (R = Me (5a), Et (5b)), resulting from the alcoholysis of the metallacycle, which could be characterized by single-crystal X-ray diffraction. This journal is
Preparation technical method of high purity 1, 1-dimethylurea
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Paragraph 0008-0013, (2019/07/16)
The invention discloses a preparation method of high purity 1, 1-dimethylurea. 1, 1-dimethylurea is a medical and pesticide intermediate and an important synthesis raw material of rocket fuel 1, 1-dimethylhydrazine which is used in national defense chemistry. According to the preparation method, a hydrazine type remover and a reaction controlling are added to avoid problems in the prior art that influences are caused by hydrazine type compound impurities, and generation of by-products is caused because of the instability of the reactants, a certain amount of a weak alkali oxidizing agent is added, and then routine cooling crystallization, centrifugation, recrystallization, and vacuum drying are carried out so as to obtain the high purify intermediate 1, 1-dimethylurea crystalline powder contains no high toxicity residue, all impurity sources are controlled and eliminated, commercial large scale product is realized, cost is reduced, and equipment is simple.
Regioselective Formal [3+2] Cycloadditions of Urea Substrates with Activated and Unactivated Olefins for Intermolecular Olefin Aminooxygenation
Wu, Fan,Alom, Nur-E,Ariyarathna, Jeewani P.,Na?, Johannes,Li, Wei
supporting information, p. 11676 - 11680 (2019/07/31)
A new class of intermolecular olefin aminooxygenation reaction is described. This reaction utilizes the classic halonium intermediate as a regio- and stereochemical template to accomplish the selective oxyamination of both activated and unactivated alkenes. Notably, urea chemical feedstock can be directly introduced as the N and O source and a simple iodide salt can be utilized as the catalyst. This formal [3+2] cycloaddition process provides a highly modular entry to a range of useful heterocyclic products with excellent selectivity and functional-group tolerance.
Investigating the Underappreciated Hydrolytic Instability of 1,8-Diazabicyclo[5.4.0]undec-7-ene and Related Unsaturated Nitrogenous Bases
Hyde, Alan M.,Calabria, Ralph,Arvary, Rebecca,Wang, Xiao,Klapars, Artis
supporting information, p. 1860 - 1871 (2019/10/11)
The widespread use of amidine and guanidine bases in synthetic chemistry merits a thorough understanding of their chemical properties. The propensity of these reagents to hydrolyze under mild conditions and generate aminolactams and aminoureas, respectively, has not been adequately described previously. During the synthesis of uprifosbuvir (MK-3682), we became aware of this liability for 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) by observing the formation of an unexpected reaction impurity and traced the root cause to low levels of N-(3-aminopropyl)-?-caprolactam present in the commercial bottle. A controlled stability study over a period of two months at 25 °C demonstrated that, above a threshold water content, DBU steadily hydrolyzed over time. Rates of hydrolysis for DBU, 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), and N,N,N′,N′-tetramethylguanidine (TMG) in organic, aqueous, and mixed solvent systems were then measured to gain a more general appreciation of what conditions to avoid in order to maintain their integrity. Our findings indicate that these bases are hydrolytically unstable in unbuffered and very basic solutions but become significantly more stable in buffered solutions at pH values below 11.6.
A practically simple, catalyst free and scalable synthesis of: N -substituted ureas in water
Tiwari, Lata,Kumar, Varun,Kumar, Bhuvesh,Mahajan, Dinesh
, p. 21585 - 21595 (2018/06/26)
A practically simple, mild and efficient method is developed for the synthesis of N-substituted ureas by nucleophilic addition of amines to potassium isocyanate in water without organic co-solvent. Using this methodology, a variety of N-substituted ureas (mono-, di- and cyclic-) were synthesized in good to excellent yields with high chemical purity by applying simple filtration or routine extraction procedures avoiding silica gel purification. The developed methodology was also found to be suitable for gram scale synthesis of molecules having commercial application in large volumes. The identified reaction conditions were found to promote a unique substrate selectivity from a mixture of two amines.
Superparamagnetic Fe3O4 Nanoparticles in a Deep Eutectic Solvent: An Efficient and Recyclable Catalytic System for the Synthesis of Primary Carbamates and Monosubstituted Ureas
Inaloo, Iman Dindarloo,Majnooni, Sahar,Esmaeilpour, Mohsen
, p. 3481 - 3488 (2018/07/29)
Superparamagnetic Fe3O4 nanoparticles were used to synthesize various primary carbamates as well as monosubstituted and N,N-disubstituted ureas. This efficient phosgene-free process used urea as an eco-friendly carbonyl source in the presence of a biocompatible deep eutectic solvent (DES) to provide an inexpensive and attractive route that afforded the products in moderate to excellent yields. The employed DES serves both a catalytic role and as the green reaction medium. The magnetic nanocatalyst and DES can been reused several times without a significant loss of activity.
4-Dodecylbenzenesulfonic acid (DBSA) promoted solvent-free diversity-oriented synthesis of primary carbamates, S-thiocarbamates and ureas
Sardarian, Ali Reza,Inaloo, Iman Dindarloo
, p. 76626 - 76641 (2015/09/22)
A simple and highly efficient solvent-free method for the conversion of alcohols, phenols, thiols and amines to primary carbamates, S-thiocarbamates and ureas in the presence of 4-dodecylbenzenesulfonic acid (DBSA) as a cheap and green Bronsted acid reagent has been described. All products were obtained in good to excellent yields and characterized using FT-IR, 1H- and 13C-NMR, MS and CHNS techniques.
Hydration of Nitriles to Amides by Thiolate-Bridged Diiron Complexes
Tong, Peng,Yang, Dawei,Li, Yang,Wang, Baomin,Qu, Jingping
, p. 3571 - 3576 (2015/08/06)
A series of nitrile-coordinating complexes [CpFe(μ-SEt)RCN]2[PF6]2 (1, R = alkyl, aryl, vinyl, amine) have been obtained by the reaction of [CpFe(μ-SEt)MeCN]2[PF6]2 (1a) with various nitriles in acetone. Complexes 1 can realize the hydration of a nitrile ligand under ambient conditions. Complexes [CpFe(μ-SEt)2(μ-η1:η1-NH(O)CR)FeCp][PF6] (2) were successfully isolated as intermediates during the hydration process, with 2b and 2e (R = CH2i = CH and Et2N) being characterized by spectrometry and X-ray crystallography. Treatment of 2 with HBF4·Et2O in the presence of nitriles released corresponding amides 3. At the same time, the structural features of the [Fe2S2] scaffold were retained. These results confirmed that the hydration of nitriles was realized by cooperative interaction on diiron centers. (Figure Presented).
Orthoamides and iminium salts, LXXV [1]. Contribution to the formation of 2-formyl-1,1,3,3-tetramethylguanidine and the isomeric 1,1-Dimethyl-3- dimethylaminomethylene-urea
Kantlehner, Willi,Ivanov, Ivo C.,Tiritiris, Ioannis
body text, p. 331 - 336 (2012/07/14)
2-Formyl-1,1,3,3-tetramethylguanidine (1) could be prepared from tris(dimethylamino)ethoxy-methane (3a) and formamide (4). Surprisingly, guanidine 1 does not result from the reaction of 1,1,3,3-tetramethylguanidine with formylating reagents such as dimeth
