- Green and efficient synthesis of thioureas, ureas, primary: O -thiocarbamates, and carbamates in deep eutectic solvent/catalyst systems using thiourea and urea
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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.
- Bagherzadeh, Nastaran,Sardarian, Ali Reza,Inaloo, Iman Dindarloo
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supporting information
p. 11852 - 11858
(2021/07/12)
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- Catalytic hydration of cyanamides with phosphinous acid-based ruthenium(ii) and osmium(ii) complexes: scope and mechanistic insights
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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
- álvarez, Daniel,Cadierno, Victorio,Crochet, Pascale,González-Fernández, Rebeca,López, Ramón,Menéndez, M. Isabel
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p. 4084 - 4098
(2020/07/09)
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- Investigating the Underappreciated Hydrolytic Instability of 1,8-Diazabicyclo[5.4.0]undec-7-ene and Related Unsaturated Nitrogenous Bases
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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.
- Hyde, Alan M.,Calabria, Ralph,Arvary, Rebecca,Wang, Xiao,Klapars, Artis
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supporting information
p. 1860 - 1871
(2019/10/11)
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- Preparation technical method of high purity 1, 1-dimethylurea
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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.
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Paragraph 0008-0013
(2019/07/16)
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- Regioselective Formal [3+2] Cycloadditions of Urea Substrates with Activated and Unactivated Olefins for Intermolecular Olefin Aminooxygenation
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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.
- Wu, Fan,Alom, Nur-E,Ariyarathna, Jeewani P.,Na?, Johannes,Li, Wei
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supporting information
p. 11676 - 11680
(2019/07/31)
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- A practically simple, catalyst free and scalable synthesis of: N -substituted ureas in water
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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.
- Tiwari, Lata,Kumar, Varun,Kumar, Bhuvesh,Mahajan, Dinesh
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p. 21585 - 21595
(2018/06/26)
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- Superparamagnetic Fe3O4 Nanoparticles in a Deep Eutectic Solvent: An Efficient and Recyclable Catalytic System for the Synthesis of Primary Carbamates and Monosubstituted Ureas
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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.
- Inaloo, Iman Dindarloo,Majnooni, Sahar,Esmaeilpour, Mohsen
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p. 3481 - 3488
(2018/07/29)
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- 4-Dodecylbenzenesulfonic acid (DBSA) promoted solvent-free diversity-oriented synthesis of primary carbamates, S-thiocarbamates and ureas
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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.
- Sardarian, Ali Reza,Inaloo, Iman Dindarloo
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p. 76626 - 76641
(2015/09/22)
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- Hydration of Nitriles to Amides by Thiolate-Bridged Diiron Complexes
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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).
- Tong, Peng,Yang, Dawei,Li, Yang,Wang, Baomin,Qu, Jingping
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p. 3571 - 3576
(2015/08/06)
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- 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
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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
- Kantlehner, Willi,Ivanov, Ivo C.,Tiritiris, Ioannis
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body text
p. 331 - 336
(2012/07/14)
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- PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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The invention relates to a process for straightening keratin fibres, comprising: (i) a step in which a straightening composition containing at least two denaturing agents is applied to the keratin fibres, (ii) a step in which the temperature of the keratin fibres is raised, using a heating means, to a temperature of between 110 and 250° C.
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- Iron(III) photo-induced degradation of isoproturon: correlation between degradation and toxicity.
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The degradation of isoproturon photoinduced by Fe(III) was investigated under both artificial and solar light. The monomeric species Fe(OH)2+ present under the experimental conditions ([Fe(III)] = 3 x 10(-4) M) is the main Fe(III) species responsible for
- Galichet, Frederic,Mailhot, Gilles,Bonnemoy, Frederique,Bohatier, Jacques,Bolte, Michele
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p. 707 - 712
(2007/10/03)
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- Process for the preparation of pure, unsymmetrically disubstituted ureas
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Process for the preparation of pure, unsymmetrically disubstituted ureas of the general formula STR1 in which R denotes a phenyl radical which is unsubstituted, or monosubstituted or polysubstituted by halogen atoms or alkyl, alkoxy, aryloxy or trifluoromethyl groups, an oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, benzoxazolyl or benzothiazolyl radical which is unsubstituted, or monosubstituted or polysubstituted by halogen atoms or alkyl, alkoxy or trifluoromethyl groups and R1 and R2 independently of one another denote a hydrogen atom or an alkyl group, where R1 and R2 are not simultaneously hydrogen or R1 and R2 together denote a butylene or pentylene group, by reaction of an N-alkyl- or N,N-dialkylurea with an unsubstituted or substituted arylamine or a heterocyclic amine in the presence of that amine which is already present in the starting material, the respective N-alkyl- or N,N-dialkylurea.
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- LACTAM AND AMIDE ACETALS. 56. SYNTHESIS OF PYRIMIDINES FROM N-CARBAMOYLAMIDINES
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N-Carbamoyl-N.N'-dimethylformamidine reacts with ethyl anthranilate to give quinazoline-2,4-dione, and with cyanoacetamide to give 4-amino-5-carbamoylpyrimidin-2-one.The reaction of dimethylacetamide diethyl acetal with urea proceeds via N-carbamoyl-N',N'-dimethylacetamidine with the subsequent formation of 4-dimethylamino-6-methyl-pyrimidin-2-one and 4,6-dimethyl-sym-triazin-2-one.
- Dozorova, E. N.,Grizik, S. I.,Granik, V. G.
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- Carbazole lipoxygenase inhibiting compounds, compositions and use
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Compounds of the formula: STR1 wherein R1 is hydrogen, C1 to C4 alkyl, C2 to C4 alkenyl, or NR2R3, wherein R2 and R3 are independently selected from hydrogen, C1 to C4 alkyl and hydroxyl, but R2 and R3 are not simultaneously hydroxyl; X is oxygen, sulfur, CO2, or NR4, wherein R4 is hydrogen, C1 to C6 alkyl, C1 to C6 alkoyl or aroyl; A is selected from C1 to C6 alkylene and C2 to C6 alkenylene; Y is selected independently at each occurrence from hydrogen, halogen, hydroxy, cyano, nitro, halosubstituted alkyl, C1 to C12 alkyl, C2 to C12 alkenyl, C1 to C12 alkoxy, C3 to C8 cycloalkyl, aryl, aryloxy, aroyl, C1 to C12 arylalkyl, C2 to C12 arylalkenyl, C1 to C12 arylalkoxy, C1 to C12 arylthicalkoxy, and substituted derivatives of aryl, aryloxy, aroyl, C1 to C12 arylalkyl, C2 to C12 arylalkenyl, C1 to C12 arylalkoxy, or C1 to C12 arylthioalkoxy, wherein C12 alkyl, alkoxy, and halosubstituted alkyl; n is a number having the values 0-4; when n=0 then Y=hydrogen; and M is hydrogen, a pharmaceutically acceptable cation, aroyl, or C1 to C12 alkoyl. These compounds are potent inhibitors of 5- and/or 12-lipoxygenase enzymes. Also disclosed are lipoxygenase inhibiting compositions and a method of inhibiting lipoxygenase.
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- Synthesis and Transformations of Some Pyridopyrimidines
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A new synthetic approach for pyridopyrimidine 3-oxides and other pyridopyrimidines has been developed.This bicyclic system readily undergoes ring opening to give a variety of products, depending on the reagent and reaction conditions. - Keywords: Cyclization with C-N or C-O bond formation; Ring opening; Substituted pyridines; Substituted 1,2,4-oxadiazoles
- Kocevar, Marijan,Koller, Joze,Stanovnik, Branko,Tisler, Miha
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p. 399 - 408
(2007/10/02)
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- PYRIDINES. XIV - ACYLATION DE PYRIDYL-LITHIOENAMIDINES. SYNTHESE DE PYRIDYL-N-ACYLENAMIDINES ET DE PYRIDYLPYRIMIDONES-4.
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The mixture of PhLi:di- or tri-methylpyridine 1:PhCN:RCOCl (R = Me, Ph, EtO, Me2N) or PHCO2Me (molar ratio 3:1:3:3) leads through the intermediates primary lithioenamines 3 and lithioenamidines 4, to acylated products, N-acylenamines (enamides) 5, β-diketones and β-ketoesters 6, C-acylenamides 7, N-acyleneamidines 8 and their cyclization derivatives, pyridylhydroxypyrimidines 10 (yield up to 60 percent) and pyridyldihydropyrimidones 11 (yield up to 10 percent).Distillation of the crude extract leads to naphthyridones 12 (yield up to 10 percent) which result from thermocyclization of the enamides 5f, 5g and 7f.Various by-products are isolated such as N,N-dimethyl-N',N'-diphenylmethyleneurea resulting from N-lithiodiphenylketimine and phenacylpyridines 13.Crotonization and oxidation of the latter compounds lead to the aza-analogues 14, 15 of dibenzoylstilbenes.
- Compagnon, Paul-Louis,Gasquez, Francoise,Kimny, Tan
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- PYRIDINES. XIII - ACYLATION DE PYRIDYL-LITHIOENAMINES PRIMAIRES. SYNTHESE DE PYRIDYL-ENAMIDES ET DE NAPHTYRIDIN-1,6 ONES-5.
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The primary lithioenamine 4a is an ambivalent nucleophile resulting from the condensation of benzonitrile with 2-s-collidyllithium.Acylation of 4a by acetyl, benzoyl, N,N-dimethylcarbamoyl chlorides, ethyl chloroformate or methyl benzoate leads to β-C-acylated 5, N-acylated 6 (enamides) and β-C,N-diacylated 7 compounds.N-acylation predominates upon C-acylation with the studied aliphatic acid chlorides, contrary to benzoylation. 4,6-Dimethyl-2-pyridyl-acetate 17 and -acetamide 18 are formed and their origin is discussed.Thermocyclization of certain enamides, carbamates 6c, 7c and urea 6d leads to 2,4-dimethyl-7-phenyl-1,6-naphthyridin-5-(6H) ones 9a and 9b, and not to pyridopyrimidones 8.
- Compagnon, Paul-Louis,Gasquez, Francoise,Kimny, Tan
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- Synthesis of N-Acyl-, N-Sulfonyl-, and N-Phosphinylphospha-λ5-azenes by a Redox-Condensation Reaction Using Amides, Triphenylphosphine, and Diethyl Azodicarboxylate
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The reaction of phosphines and amides with diethyl azodicarboxylate (DAD) produced phospha-λ5-azenes.Thus aromatic amides and those aliphathic amides with electron-withdrawing substituents gave N-acyl-P,P,P-triphenylphospha-λ5-azenes (5) when triphenylphosphine (TPP) was employed.Both aryl- and alkylsulfonamides reacted with TPP and DAD to produce the N-sulfonylphospha-λ5-azenes (9).Diphenylphosphinamide (10) and ethyl carbamate (12) also produced the respective phosphazenes (11 and 13) with TPP and DAD.Secondary carboxamides and sulfonamides did not react with TPP and DAD.The reaction of triethyl phosphite with sulfonamides in the presence of DAD produced the phosphorimidates (20) in an analogous reaction, along with the corresponding N,N-diethylsulfonamides and the deethylated adduct of triethyl phosphite and DAD (23).Triethyl phosphite-DAD failed, however, to give a phosphorimidate with carboxamides but gave, instead, the rearranged adduct of DAD and triethyl phosphite (19).Tris(dimethylamino)phosphine reacted with sulfonamides and DAD but the products were the corresponding ethyl N-sulfonylcarbamates (26) rather than the phosphazenes.Tris(dimethylamino)phosphine reacted with azodicarbonamide (a molecule which contains both the azo and carboxamide groups) with the production of N,N-dimethylurea, again without formation of the phosphazene.Finally, the reaction of triphenylarsine with benzenesulfonamide and DAD produced N-(phenylsulfonyl)triphenylarsa-λ5-azene (30) but triphenylstibene with DAD and benzenesulfonamide only gave triphenylstibene oxide.Mechanistic possibilities for these reactions are also discussed.
- Bittner, Shmuel,Assaf, Yonit,Krief, Penina,Pomerantz, Martin,Ziemnicka, Barbara T.,Smith, Christina G.
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p. 1712 - 1718
(2007/10/02)
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- Neighbouring Group Participation in Formation of Condensed Azines. Formation of Pyrazolo(3,4-b)pyrazines, Isoxazolo(4,5-b)pyrazines and Isothiazolo(5,4-b)pyridine (Heterocycles, CCX)
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Pyrazine- and pyridinecarboxamidoximes with an amino, potentially tautomeric hydroxy or mercapto group in ortho position could be transformed in the appropriate condensed azines.In this manner, representatives of pyrazolo(3,4-b)pyrazine, isoxazolo(4,5-b)pyrazine and isothiazolo(5,4-b)pyridine ring system were synthesized and some transformations investigated. - Keywords: Cyclization with N-N, N-O or N-S bond formation; Heterocyclic compounds
- Kocevar, Marjan,Vercek, Bojan,Stanovnik, Branko,Tisler, Miha
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p. 731 - 744
(2007/10/02)
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- NEW SYNTHETIC APPROACH FOR PYRAZOLOPYRAZINES AND ISOXAZOLOPYRAZINES
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A new synthetic approach has been developed for the synthesis of pyrazolepyrazines (7) and isoxazolopyrazines (22) from the corresponding substituted pyrazines.
- Kocevar, Marjan,Tisler, Miha,Stanovnik, Branko
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p. 339 - 342
(2007/10/02)
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