- Synthesis and Structure of 1-Substituted Semithioglycolurils
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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.
- Baranov, Vladimir V.,Galochkin, Anton A.,Kravchenko, Angelina N.,Makhova, Nina N.,Nelyubina, Yulia V.
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p. 2563 - 2571
(2020/09/07)
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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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- Continuous flow reduction of artemisinic acid utilizing multi-injection strategies - Closing the gap towards a fully continuous synthesis of antimalarial drugs
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One of the rare alternative reagents for the reduction of carbon-carbon double bonds is diimide (HN=NH), which can be generated in situ from hydrazine hydrate (N2H4·H2O) and O2. Although this selective method is extremely clean and powerful, it is rarely used, as the rate-determining oxidation of hydrazine in the absence of a catalyst is relatively slow using conventional batch protocols. A continuous high-temperature/high-pressure methodology dramatically enhances the initial oxidation step, at the same time allowing for a safe and scalable processing of the hazardous reaction mixture. Simple alkenes can be selectively reduced within 10-20 min at 100-120°C and 20 bar O2 pressure. The development of a multi-injection reactor platform for the periodic addition of N2H4·H2O enables the reduction of less reactive olefins even at lower reaction temperatures. This concept was utilized for the highly selective reduction of artemisinic acid to dihydroartemisinic acid, the precursor molecule for the semisynthesis of the antimalarial drug artemisinin. The industrially relevant reduction was achieved by using four consecutive liquid feeds (of N2H4·H2O) and residence time units resulting in a highly selective reduction within approximately 40 min at 60°C and 20 bar O2 pressure, providing dihydroartemisinic acid in ≥93% yield and ≥95% selectivity.
- Pieber, Bartholom?us,Glasnov, Toma,Kappe, C. Oliver
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supporting information
p. 4368 - 4376
(2015/03/14)
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- One-Pot Synthesis of N-Monosubstituted Ureas from Nitriles via Tiemann Rearrangement
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Amidoximes, obtained from the reaction of nitriles with hydroxylamine, underwent Tiemann rearrangement in the presence of benzenesulfonyl chlorides (TsCl or o-NsCl) to form the N-substituted cyanamides. Subsequently, acidic hydrolysis of the cyanamides afforded the corresponding N-monosubstituted ureas. The synthesis of N-monosubstituted ureas from nitriles was accomplished by three steps in one pot, which provides a direct access to versatile N-monosubstituted urea derivatives from a wide variety of nitriles.
- Wang, Chien-Hong,Hsieh, Tsung-Han,Lin, Chia-Chi,Yeh, Wen-Hsiung,Lin, Chih-An,Chien, Tun-Cheng
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supporting information
p. 1823 - 1826
(2015/08/06)
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- PYRIMIDINEDIONE COMPOUNDS AGAINST CARDIAC CONDITIONS
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Provided are novel pyrimidine dione compounds and pharmaceutically acceptable salts thereof, that are useful for the treatment of hypertrophic cardiomyopathy (HCM) and conditions associated with left ventricular hypertrophy or diastolic dysfunction. The synthesis and characterization of the compounds and pharmaceutically acceptable salts thereof, are described, as well as methods for treating HCM and other forms of heart disease.
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Paragraph 0121-0122
(2015/01/07)
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- In situ generation of diimide from hydrazine and oxygen: Continuous-flow transfer hydrogenation of olefins
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No catalyst required! A highly efficient, catalyst-free process to generate diimide in situ from hydrazine monohydrate and molecular oxygen for the selective reduction of alkenes has been developed. The use of a gas-liquid segmented flow system allowed safe operating conditions and dramatically enhanced this atom-economical reaction, resulting in short processing times. Copyright
- Pieber, Bartholomaeus,Martinez, Sabrina Teixeira,Cantillo, David,Kappe, C. Oliver
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supporting information
p. 10241 - 10244
(2013/10/21)
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- Carboxylic acid-catalyzed one-pot synthesis of cyanoacetylureas and their cyclization to 6-aminouracils in guanidine ionic liquid
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A novel, one-pot, carboxylic acid-catalyzed synthesis of cyanoacetylureas via in situ generated ureas and their cyclization to 6-aminouracils in the presence of the guanidine-based ionic liquid 1,1,3,3-tetramethylguanidine lactate [TMG][Lac] is described. The ureas were synthesized from amines and potassium cyanate, which on reaction with cyanoacetic acid in the presence of acetic anhydride in the same pot afforded cyanoacetylureas, which undergo cyclization in [TMG][Lac] as solvent as well as catalyst to afford 6-aminouracils. One-pot synthesis of cyanoacetylureas, efficient and rapid cyclization, better yield, shorter reaction time, easy workup procedure, and recyclability of the ionic liquid are some advantages of this procedure.
- Chavan, Sunil S.,Shelke, Rupesh U.,Degani, Mariam S.
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p. 399 - 403
(2013/05/21)
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- An improved method for the preparation of alkyl/arylurea derivatives using chlorocarbonylsulfenyl chloride as carbonylating agent
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A convenient procedure has been developed for preparation of aminesubstituted or monomethylamine-substituted alkyl/arylurea derivatives. The method comprises two steps-reaction of an alkyl/aryl amine with chlorocarbonylsulfenyl chloride in a non-polar solvent to produce an alkyl/arylcarbonylsulfenyl chloride, then reaction of this alkyl/ arylcarbonylsulfenyl chloride with ammonia or monomethylamine in a two-phase reaction with a phase-transfer catalyst, to produce the corresponding alkyl/aryl-substituted urea. Springer Science+Business Media B.V. 2012.
- Manidhar,K. Uma Maheswara Rao,C. Suresh Reddy,Ch. Syamasunder,Adeppa,Misra, Krishna
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p. 2479 - 2489
(2013/03/13)
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- Ionic liquid mediated one-pot synthesis of 6-aminouracils
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A novel, one-pot synthesis of 6-aminouracils via in situ generated ureas and cyanoacetylureas in the presence of an ionic liquid catalyst, 1,1,3,3-tetramethylguanidine acetate, is described. The catalyst can be recycled for five consecutive runs without loss of activity. The mechanism for the ring closure of cyanoacetylurea to 6-aminouracil is also discussed.
- Chavan, Sunil S.,Degani, Mariam S.
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supporting information; experimental part
p. 296 - 299
(2012/03/26)
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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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- Diazinane Compounds
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The present invention relates to novel compounds of the general formula (I) wherein R1, R2, R3 and R4 are as defined, having a positive allosteric GABAB receptor (GBR) modulator effect, methods for the preparation of said compounds and to their use, optionally in combination with a GABAB agonist, for the inhibition of transient lower esophageal sphincter relaxations, for the treatment of gastroesophageal reflux disease, as well as for the treatment of functional gastrointestinal disorders and irritable bowel syndrome (IBS).
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Page/Page column 12
(2009/04/24)
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- XANTHINE COMPOUNDS HAVING A POSITIVE ALLOSTERIC GABAB RECEPTOR MODULATOR EFFECT
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The present invention relates to novel xanthine compounds of the general formula (I) wherein R1, R2, R3 and R4 are as defined, having a positive allosteric GABA Breceptor (GBR) modulator effect, methods for the preparation of said compounds and to their use, optionally in combination with a GABA Bagonist, for the inhibition of transient lower esophageal sphincter relaxations, for the treatment of gastroesophageal reflux disease, as well as for the treatment of functional gastrointestinal disorders and irritable bowel syndrome (IBS).
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Page/Page column 55; 56
(2008/12/08)
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- Process for the preparation of asymmetrically substituted ureas
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Process for the preparation of asymmetrically substituted ureas by reaction of a gaseous mixture of isocyanic acid and ammonia having a temperature of 260° to 600° C. with a primary or secondary amine.
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- Substituted 1,3,5-triazinetriones, for use against parasitic protozoa
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Protecting against parasitic protozoa with substituted 1,3,5-triazinetriones of the formula STR1 in which R1 represents aromatic or heteroaromatic radicals, each of which is optionally substituted, R2 represents H, alkyl, alkenyl, alkinyl or aralkyl, each of which is optionally substituted, R3 represents one or more identical or different radicals from the group consisting of hydrogen, halogen, alkyl, halogenoalkyl, alkoxy, alkylthio, halogenoalkoxy, halogenoalkylthio, cyano, alkoxycarbonyl, alkylsulphonyl and halogenoalkylsulphonyl, R4 represents hydrogen, a straight-chain, branched or cyclic alkyl radical, alkenyl, alkinyl, aralkyl or aryl, each of which is optionally substituted, and R5 represents hydrogen, optionally substituted alkyl, alkenyl, alkinyl or aralkyl. Also novel intermediates therefor.
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- HYDROGEN BONDED COMPLEXES IV; UREA-PHENOL COMPLEXES
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A number of crystalline, hydrogen-bonded complexes of ureas and phenols are reported.The most commonly observed urea-phenol ratio is 1:1, but some complexes with ratios of 2:1, 1:2 and 1:3 were encountered.The structures of these complexes are discussed and one degradative reaction is described.
- Barry, John E.,Finkelstein, Manuel,Hutchins, Gudrun A.,Ross, Sidney D.
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p. 2151 - 2156
(2007/10/02)
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- Some Extensions of von Braun (BrCN) Reaction on Organic Bases: Part II
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Extensions of von Braun Cyanogen bromide reaction on Ephedra alkaloids and simpler bases have resulted in synthesis of substituted oxazolidines and a whole series of nitrogen analogues of ephedrine, desoxy ephedrine and simpler amines.The general applicability and limitations of such extension of the reaction are also discussed. - Key words: von Braun Cyanogen Bromide Reaction
- Malik, Abdul,Afza, Nighat,Siddiqui, Salimuzzaman
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p. 512 - 518
(2007/10/02)
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- N-(1-carboxy-3-methylthio)propyl urea derivatives and compositions having plant-growth regulating properties
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Compounds corresponding to the general formulae: EQU1 in which R represents hydrogen, an alkyl radical, a halogenated alkyl raal, a cycloalkyl radical, an optionally substituted aryl radical, an optionally substituted aralkyl radical, an acyl radical, aroyl radical or an optionally substituted heterocycle; R1 and R3, which may be the same or different, represent hydrogen, aralkyl radical containing 1 to 5 carbon atoms; R2 represents hydrogen, an alkyl radical (optionally halogenated or substituted by a hydroxyl), a formyl radical, an acyl radical, a carbamoyl radical monosubstituted or disubstituted on the nitrogen; R and R2 cannot both represent hydrogen; R4 is the carboxylic acid radical or one of its ester, amide, nitrile derivatives or a salt of an alkaline metal, alkaline-earth metal or heavier metal, in which case several molecules (1) can be associated with the metal atom; X represents oxygen or sulphur, and their salts, especially their sulphonium salts. Such compounds are useful for modifying the growth of plants.
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