1118-12-3Relevant articles and documents
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)
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
Synthesis and Structure of 1-Substituted Semithioglycolurils
Baranov, Vladimir V.,Galochkin, Anton A.,Kravchenko, Angelina N.,Makhova, Nina N.,Nelyubina, Yulia V.
, p. 2563 - 2571 (2020)
Two methods for the synthesis of previously unavailable 1-substituted semithioglycolurils were developed. These methods consist of the cyclocondensation of 1-substituted ureas with 4,5-dihydroxy- or 4,5-dimethoxyimidazolidine-2-thione or glyoxal, followed by the reaction of the resulting 1-substituted 4,5-dihydroxyimidazolidine-2-ones with HSCN in a two-step one-pot procedure. Two of the desired semithioglycolurils were obtained as conglomerates.
Reaction of N-alkyl-N′-(trimethylsilyl)carbodiimides with nitrating agents. The synthesis of N-(tert-butyl)-N′-nitrocarbodiimide
Churakov,Ioffe,Voronin,Tartakovsky
, p. 56 - 60 (2018)
Reaction of N-Alk-N′-(trimethylsilyl)carbodiimides (Alk = Me, But) with nitrating agents (N2O5, (NO2)2SiF6) affords alkyl(nitro)cyanamides and N-alkyl-N′-nitrocarbodiimides. The product ratio depends on the reaction conditions. N-(tert-butyl)-N′-nitrocarbodiimide can be obtained in almost pure form. This compound is stable at temperatures below 10 °C. Its structure was confirmed by 1Н, 13C, and 14N NMR. The reaction of N-(tert-butyl)-N′-nitrocarbodiimide with amines provides a new route to N-alkyl(aryl)-substituted N′-(tert-butyl)-N″-nitroguanidines.
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.
A Physical Organic Approach to Tuning Reagents for Selective and Stable Methionine Bioconjugation
Christian, Alec H.,Jia, Shang,Cao, Wendy,Zhang, Patricia,Meza, Arismel Tena,Sigman, Matthew S.,Chang, Christopher J.,Toste, F. Dean
supporting information, p. 12657 - 12662 (2019/09/04)
We report a data-driven, physical organic approach to the development of new methionine-selective bioconjugation reagents with tunable adduct stabilities. Statistical modeling of structural features described by intrinsic physical organic parameters was applied to the development of a predictive model and to gain insight into features driving the stability of adducts formed from the chemoselective coupling of oxaziridine and methionine thioether partners through Redox Activated Chemical Tagging (ReACT). From these analyses, a correlation between sulfimide stabilities and sulfimide ν (C=O) stretching frequencies was revealed. We exploited the rational gains in adduct stability exposed by this analysis to achieve the design and synthesis of a bis-oxaziridine reagent for peptide stapling. Indeed, we observed that a macrocyclic peptide formed by ReACT stapling at methionine exhibited improved uptake into live cells compared to an unstapled congener, highlighting the potential utility of this unique chemical tool for thioether modification. This work provides a template for the broader use of data-driven approaches to bioconjugation chemistry and other chemical biology applications.
PROCESS FOR STRAIGHTENING KERATIN FIBRES WITH A HEATING MEANS AND DENATURING AGENTS
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, (2010/03/02)
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.
Bile-acid derived compounds for enhancing oral absorption and systemic bioavailability of drugs
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, (2008/06/13)
Disclosed are compounds that exhibit high transport across the intestinal wall of an animal. The compounds may optionally be linked to drugs that are poorly absorbed or poorly transported across the intestinal wall after oral administration to provide for enhanced therapeutic, and optionally prolonged therapeutic, systemic blood concentrations of the drugs upon oral administration of the drug-compound conjugate. Also disclosed are pharmaceutical compositions containing and methods of using such compounds.
A simple conversion of amines into monosubstituted ureas in organic and aqueous solvents
Liu, Qi,Luedtke, Nathan W.,Tor, Yitzhak
, p. 1445 - 1447 (2007/10/03)
A versatile and highly efficient synthesis of monosubstituted ureas is described. The reaction of an amine with 4-nitrophenyl-N-benzylcarbamate, followed by hydrogenolysis, provides the corresponding urea in high yield and purity. This carbamate can also be employed for the derivatization of water-soluble polyamines (e.g. aminoglycoside antibiotics), while other reagents (e.g. benzylisocyanate) fail to give the desired products in any significant yield.
Increased intensity of tert-butoxyl radical emission in 4-chloro-2- methylphenoxyacetic acid (MCPA) synthesis
Jezierski, Adam,Zakrzewski, Jerzy,Moszczyski, Wiesaw
, p. 1229 - 1232 (2007/10/03)
The important herbicide, 2-methyl-4-chlorophenoxyacetic acid (MCPA) was synthesized by the chlorination of 2-methylphenoxyacetic acid with tert-butyl hypochlorite in the presence of methyl N,N-dimethylglycinate as a catalyst, giving a high yield and regioselectivity. The reaction was investigated using the spin-trapping technique in electron paramagnetic resonance measurement conditions, with nitrosodurene as a spin trap. Increased intensity emission of the tert-butoxyl radical (2.9 times in relation to the starting level) was observed after the catalyst had been introduced into the reaction mixture, indicating a free radical mechanism for the reaction.
SYNTHESIS OF METHYL 3-(N'-ALKYLUREIDO)-2-METHYL-2-PROPENOATES AND THEIR CYCLIZATION TO 3-ALKYL-5-METHYLURACILS
Ledvina, Miroslav,Farkas, Jiri
, p. 676 - 688 (2007/10/02)
Stereoisomeric methyl 3-(N'-alkylureido)-2-methyl-2-propenoates (Ia-Id) were prepared by acid-catalyzed reaction of N-alkylureas (R = methyl, benzyl, isopropyl and tert-butyl) with methyl 3-methoxy-2-methyl-2-propenoate (III).Reaction of the ester III with N-tert-butylthiourea afforded the thioureides (E)-Ie and (Z)-Ie.On treatment with sodium methoxide in methanol, compounds Ia-Ic cyclized to the corresponding 3-alkyl-5-methyluracils IIa-IIc whereas compounds Id and Ie underwent only a base catalyzed E/Z isomerization with (E)-isomers predominating.
