620-50-8Relevant academic research and scientific papers
Di-tert-butyl peroxide (DTBP)-mediated synthesis of symmetrical N,N′-disubstituted urea/thiourea motifs from isothiocyanates in water
Chen, Ling,Dong, Yibo,Wu, Yangjie,Yang, Jinchen,Zhang, Jinli
supporting information, (2021/12/01)
ABATRACT: A direct approach to N,N′-disubstituted urea/thiourea from the self-condensation reactions of isothiocyanates in water has been developed. This access tolerated a wide range of functional groups on the aromatic ring, providing a practical and environment-friendly process to N,N′-disubstituted urea/thiourea in moderate to excellent yields from safe and easily available starting materials. A plausible mechanism of the desulfurization self-condensation reaction for urea was also proposed and the role of di-tert-butyl peroxide (DTBP) and copper catalyst in the present strategy was demonstrated with the help of ESI mass spectrometry of intermediate studies.
Amide-assisted rearrangement of hydroxyarylformimidoyl chloride to diarylurea
Jin, Yi,Liu, Xiaoyu,Song, Xizhong,Yu, Wei
supporting information, (2021/11/11)
A novel amide-assisted rearrangement reaction of hydroxybenzimidoyl chloride has been established for the efficient synthesis of 1,3-diphenylurea derivatives. A variety of electronically and sterically different 1,3-diphenylurea derivatives can be obtained in good to excellent yields, and a proposed reaction mechanism is also presented.
Investigation of active sites using solid state 27Al and 31P MAS NMR in ceramic amorphous aluminophosphate materials prepared from different potassium salts of phosphate for the synthesis of diphenyl urea derivatives
Harish,Kathyayini,Baby, Bindhu,Nagaraju
, (2021/04/19)
Ceramic amorphous aluminophosphate (CAmAlP) catalysts were prepared by precipitation method using different phosphate salts of potassium such as KH2PO4, K4P2O7 and K2HPO4 as well as H3PO4. The prepared materials were characterized by PXRD, FT-IR, XPS, SEM, BET Surface area, NH3-TPD, 27Al NMR and 31P NMR analytical methods. The catalytic activity of the materials was checked in the synthesis of diphenyl urea (DPU) from aniline and diethyl carbonate, under refluxing conditions. Further, the general application of the catalysts was tested using various substituted anilines. The recyclability of the catalysts was also studied. Uncertainties in percentage yields were calculated to check the reproducible surface properties. The P-XRD, BET Surface area and NH3-TPD results indicated that the materials were amorphous with mesoporous texture, surface areas and acidities in the range 200–260 m2/g and 0.4–0.7 mmol/g respectively. 27Al NMR studies revealed that Al is present in three different coordination states such as tetrahedral, pentagonal and octahedral. The relative percentages of these Al sites depends on the type of the potassium precursor phosphate salt used. Both tetrahedral and pentagonal Al sites in conjunction with each other represented catalytically active sites. An increase in the pentagonal sites contributed to additional increments to the catalytic activity of CAmAlP. The catalyst prepared from KH2PO4 was found to be the best and demonstrated 96% DPU yield.
Palladium-Catalyzed Aerobic Oxidative Carbonylation of Amines Enables the Synthesis of Unsymmetrical N,N′-Disubstituted Ureas
Zeng, Honglan,Du, Hongyan,Gong, Xu,Zhang, Jie,Han, Wei
, p. 1223 - 1226 (2021/06/02)
A ligand-free palladium-catalyzed aerobic oxidative carbonylation of amines for the synthesis of ureas, particular unsymmetrically N,N′-disubstituted ureas, which cannot be accessed by any other palladium-catalyzed oxidative carbonylation of amines to date, is presented. An array of symmetrical and unsymmetrical ureas were straightforwardly synthesized by using inexpensive, readily available, stable, and safe amines with good to excellent yields under a pressure of 1 atm. This novel method employs oxygen as the sole oxidant and offers an attractive alternative to transition-metal-based oxidant systems.
An Improved Synthesis of Urea Derivatives from N -Acylbenzotriazole via Curtius Rearrangement
Agrahari, Anand K.,Singh, Anoop S.,Singh, Sumit K.,Tiwari, Vinod K.,Yadav, Mangal S.
, p. 3443 - 3450 (2019/09/07)
The good leaving tendency of the benzotriazole moiety has been exploited for the synthesis of symmetric, unsymmetric, N -acyl, and cyclic ureas in good yields from N -acylbenzotriazoles by treating the latter with various amines in the presence of TMSN 3 /Et 3 N in a sealed tube. The salient features of the devised protocol includes the high-yield, mild, metal-free, one-pot reaction conditions, and short reaction time. Furthermore, in many cases, no column chromatography is required for the purification.
N,N'-disubstituted urea compound and synthesis method thereof
-
Paragraph 0042-0045, (2019/04/10)
The invention discloses an N,N'-disubstituted urea compound and a preparation method thereof. N-alkyl acyloxy amide is taken as a raw material and a dichloro(p-cymene)ruthenium(II) dimer complex is taken as a catalyst for carrying out a reaction in an organic solvent under the presence of silver acetate, and the N,N'-disubstituted urea compound is prepared. Compared with the prior art, the methodhas the following advantages that only an amide derivative is taken as a raw material, reaction conditions are mild, the application range of substrates is wide, operation is simple and convenient, the catalyst is low in price, and selectivity of the product is high.
Hydrogen-Bonded Homoleptic Fluoride-Diarylurea Complexes: Structure, Reactivity, and Coordinating Power
Pfeifer, Lukas,Engle, Keary M.,Pidgeon, George W.,Sparkes, Hazel A.,Thompson, Amber L.,Brown, John M.,Gouverneur, Véronique
supporting information, p. 13314 - 13325 (2016/10/22)
Hydrogen bonding with fluoride is a key interaction encountered when analyzing the mode of action of 5′-fluoro-5′-deoxyadenosine synthase, the only known enzyme capable of catalyzing the formation of a C-F bond from F-. Further understanding of the effect of hydrogen bonding on the structure and reactivity of complexed fluoride is therefore important for catalysis and numerous other applications, such as anion supramolecular chemistry. Herein we disclose a detailed study examining the structure of 18 novel urea-fluoride complexes in the solid state, by X-ray and neutron diffraction, and in solution phase and explore the reactivity of these complexes as a fluoride source in SN2 chemistry. Experimental data show that the structure, coordination strength, and reactivity of the urea-fluoride complexes are tunable by modifying substituents on the urea receptor. Hammett analysis of aryl groups on the urea indicates that fluoride binding is dependent on σp and σm parameters with stronger binding being observed for electron-deficient urea ligands. For the first time, defined urea-fluoride complexes are used as fluoride-binding reagents for the nucleophilic substitution of a model alkyl bromide. The reaction is slower in comparison with known alcohol-fluoride complexes, but SN2 is largely favored over E2, at a ratio surpassing all hydrogen-bonded complexes documented in the literature for the model alkyl bromide employed. Increased second-order rate constants at higher dilution support the hypothesis that the reactive species is a 1:1 urea-fluoride complex of type [UF]- (U = urea) resulting from partial dissociation of the parent compound [U2F]-. The dissociation processes can be quantified through a combination of UV and NMR assays, including DOSY and HOESY analyses that illuminate the complexation state and H-bonding in solution.
An efficient one-pot synthesis of: N, N ′-disubstituted ureas and carbamates from N -acylbenzotriazoles
Singh, Anoop S.,Kumar, Dhananjay,Mishra, Nidhi,Tiwari, Vinod K.
, p. 84512 - 84522 (2016/10/12)
A facile and high-yielding one-pot synthesis of carbamates and N,N′-disubstituted symmetrical ureas from N-acylbenzotriazoles has been devised. It is believed that, the intermediate acyl-azide undergo Curtius rearrangement and in different solvents gives different products i.e. carbamates in alcohols and N,N′-disubstituted symmetrical urea in THF.
Method for catalytically synthesizing N, N'-disubstituted urea derivative and imidazole derivative
-
Paragraph 0044; 0045; 0046; 0047, (2016/10/17)
The present invention relates to a green and efficient method for preparing an N, N'-disubstituted urea derivative and an imidazole derivative. The method for preparing the N, N'-disubstituted urea derivative by condensation of an aromatic amine with a carbonate ester comprises: by using ionic liquid loaded magnetic nanoparticles as a catalyst, at the temperature of 60-100 DEG C, and at a normal pressure, and in a condition of solvent-free, performing a condensing reaction on the aromatic amine and the carbonate ester for 8-14 hours to obtaina corresponding N, N'-disubstituted urea derivative; by using a magnetic nanoparticle-loaded ionic liquid as a catalyst and by using ethanol as a solvent, performing Michael addition reaction of a substituted imidazole and an electron-deficient olefin for 1-5 hours at the temperature of 10-50 DEG C and at a normal pressure to obtain a corresponding imidazole derivative, wherein the catalyst is as shown in the specification. Experiments verify that after the reaction is completed, the catalyst is recycled simply through an external magnetic field and can be repeatedly used for many times, but the activity is not obviously reduced. The catalytic system is simple in operation and high in yield, and the reusability is good, so that the method has a good industrial prospect.
Synthesis of unsymmetrical 2-pyridyl ureas via selenium-catalyzed oxidative carbonylation of 2-aminopyridine with aromatic amines
Zhang, Xiaopeng,Li, Desheng,Ma, Xueji,Wang, Yan,Zhang, Guisheng
, p. 1357 - 1363 (2013/07/05)
A simple, one-pot, phosgene-free approach to a series of unsymmetrical 2-pyridyl ureas starting from 2-aminopyridine and various aromatic amines is reported for the first time. The procedure employs inexpensive selenium as the catalyst, and carbon monoxide (instead of phosgene) as the carbonyl reagent. The products are obtained in moderate to good yields via selenium-catalyzed oxidative cross-carbonylation of the substrate amines in the presence of oxygen. The selenium functions as a phase-transfer catalyst and can be recovered easily and reused without any significant degradation of its catalytic activity.
