- Isocyanates from Alkyl and Aralkyl Halides
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Alkyl and aralkyl halides were converted to isocyanates (63percent-89percent) by treatment with the silver salt of nitrocyanamide.This new reaction offers the first direct conversion of an organic halide to an isocyanate that is general, efficient, and facile.
- Boyer, Joseph H.,Manimaran, Thanikavelu
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- Mechanistic Basis for Efficient, Site-Selective, Aerobic Catalytic Turnover in Pd-Catalyzed C-H Imidoylation of Heterocycle-Containing Molecules
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A recently reported Pd-catalyzed method for oxidative imidoylation of C-H bonds exhibits unique features that have important implications for Pd-catalyzed aerobic oxidation catalysis: (1) The reaction tolerates heterocycles that commonly poison Pd catalysts. (2) The site selectivity of C-H activation is controlled by an N-methoxyamide group rather than a suitably positioned heterocycle. (3) A Pd0 source, Pd2(dba)3 (dba = dibenzylideneacetone), is superior to Pd(OAc)2 as a precatalyst, and other PdII sources are ineffective. (4) The reaction performs better with air, rather than pure O2. The present study elucidates the origin of these features. Kinetic, mechanistic, and in situ spectroscopic studies establish that PdII-mediated C-H activation is the turnover-limiting step. The tBuNC substrate is shown to coordinate more strongly to PdII than pyridine, thereby contributing to the lack of heterocycle catalyst poisoning. A well-defined PdII-peroxo complex is a competent intermediate that promotes substrate coordination via proton-coupled ligand exchange. The effectiveness of this substrate coordination step correlates with the basicity of the anionic ligands coordinated to PdII, and Pd0 catalyst precursors are most effective because they selectively afford the PdII-peroxo in situ. Finally, elevated O2 pressures are shown to contribute to background oxidation of the isonitrile, thereby explaining the improved performance of reactions conducted with air rather than 1 atm O2. These collective results explain the unique features of the aerobic C-H imidoylation of N-methoxybenzamides and have important implications for other Pd-catalyzed aerobic C-H oxidation reactions.
- Tereniak, Stephen J.,Stahl, Shannon S.
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- N-DIFLUORPHOSPHORYL-N',N''-BIS(T-BUTYL)-SCWEFELTRIIMID
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(t-BuN=)2S=NPOF2 (5) is prepared in 55 percent yield from (t-BuNH=)3S and OPF2NCO.In moist ether water is added to 5 forming (t-Bu-N-)2S(O)NPOF2 (6) almost quantitatively.
- Tesky, F. M.,Mews, R.
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- Monomeric (Pentamethylcyclopentadienyl)iridium Imido Compounds: Synthesis, Structure, and Reactivity
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The monomeric terminal imido complexes Cp*IrNR (Cp* = η5-C5Me5; 1a, R = t-Bu; 1b, R = SiMe2t-Bu; 1c, R = 2,6-Me2C6H3; 1d, R = 2,6-i-Pr2C6H3) were prepared from [Cp*IrCl2]2 (2) and 4 equiv of the corresponding lithium amide LiNHR in THF. In addition, the complexes Cp*Ir(RNH2)Cl2 (3a, R = t-Bu; 3d, R = 2,6-i-Pr2C6H3) were made from an amine and [Cp*IrCl2]2 (2) and dehydrochlorinated with KN(SiMe3)2 to provide an alternate route to 1a,d. Efficient exchange occurred between 1a and arylamines, leading to 1c,d and tert-butylamine. tert-Butylimido complex 1a, a weak nucleophile, reacted with MeI to form [Cp*IrI2]2 and Me3Nt-Bu+I-. Coupling of the imido ligand in 1a with CNt-Bu and CO gave Cp*Ir(t-BuNCNt-Bu)(CNt-Bu) (4) and Cp*Ir(t-BuNCO)(CO) (5a), respectively. Cp*IrPPh3(t-BuNCO) (5b) was formed from 1a, PPh3, and CO. The bridging imido complex Cp*IrNt-Bu(dppePt) (6, dppe = 1,2-bis(diphenylphosphino)ethane) was prepared from 1a and dppePt(C2H4). Complex 1a and CO2 gave the cycloadduct Cp*Ir(Nt-BuOCO) (7a), which added PPh3 to form Cp*IrPPh3(Nt-BuOCO) (7b). Two equivalents of dimethylacetylenedicarboxylate reacted with 1a to yield the pyrrole complex Cp(Ir(η4-RCCRNt-BuRCCR) (8, R = CO2Me). Maleic anhydride was added to 1a to give Cp*Ir[Nt-BuC(O)CH=CHCO2] (9a), which reacted with CO to yield Cp*Ir(CO)[Nt-BuC(O)CH=CHCO2] (9b). Compounds 1a-d, 7a, and 8 were structurally characterized by X-ray diffraction; imido complexes 1a-d have short Ir-N distances and nearly linear Ir-N-C(Si) angles, consistent with the presence of a metal-nitrogen triple bond.
- Glueck, David S.,Wu, Jianxin,Hollander, Frederick J.,Bergman, Robert G.
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- Phosphazenes: Efficient organocatalysts for the catalytic hydrosilylation of carbon dioxide
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Phosphazene superbases are efficient organocatalysts for the metal-free catalytic hydrosilylation of carbon dioxide. They react with CO2 to form the respective phosphine oxides, but in the presence of hydrosilanes, CO2 can be selectively reduced to silyl formates, which can in turn be reduced to methoxysilanes by addition of an extra loading of silanes. Activities reach a TOF of 32 h-1 with a TON of 759. It is also shown that unexpectedly, N,N-dimethylformamide can reduce CO2 to a mixture of silyl formates, acetals and methoxides in the absence of any catalyst.
- Courtemanche, Marc-André,Légaré, Marc-André,Rochette, étienne,Fontaine, Frédéric-Georges
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- 2-(aryl (azacycloalkane-1-yl) methyl) phenol derivatives and uses thereof
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The invention discloses 2-(aryl (azacycloalkane-1-yl) methyl) phenol derivatives and application thereof, and belongs to the technical field of medicines. The invention provides a compound shown in a formula I or pharmaceutically acceptable salt thereof. The series of compounds have good inhibitory activity on the histone demethylase KDM4 family in vitro, the median inhibitory concentration (IC50) of most molecules on KDM4D is less than 500 nM, and the compounds have good inhibitory effect on proliferation of various human tumor cell strains in vitro, so that the series of compounds provide a new effective choice for developing targeted histone demethylase KDM4D drugs and preparing drugs for treating and/or preventing cancers and reproductive system diseases, and have good application prospects.
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Paragraph 0293-0295
(2021/07/24)
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- Reversible CO2 fixation by N-heterocyclic imines forming water-stable zwitterionic nitrogen-base-CO2 adducts
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Zwitterionic Lewis base adducts between nitrogen bases and CO2 play a pivotal role as transient intermediates in many projects aiming at CO2 capture, storage and utilization. Yet, fundamental questions about the required parameters for the formation of isolable adducts remain and only a single adduct (TBD-CO2) has been characterized unequivocally. Using a combination of NMR spectroscopy, single-crystal X-ray diffraction, IR spectroscopy and quantum chemistry, we systematically explore the formation and properties of the CO2 adducts with amidines (DBN), guanidines (MTBD) and N-heterocyclic imines. Spectroscopic and theoretical results show that the stability of the NHI-CO2 adducts is largely governed by the nature of the N-heterocycle and the substituent at the exocyclic nitrogen atom. The surprising stability of some NHI-CO2 adducts towards hydrolysis can be ascribed to the hydrophobic CO2 binding site of the nitrogen bases and offers new opportunities in the field of CO2 capture and utilization.
- Wilm, Lukas F. B.,Eder, Tobias,Mück-Lichtenfeld, Christian,Mehlmann, Paul,Wünsche, Marius,Bu?, Florenz,Dielmann, Fabian
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supporting information
p. 640 - 648
(2019/02/14)
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- Synthesis method of tertiary butyl isocyanate
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The invention relates to a synthesis method of tertiary butyl isocyanate. The method comprises the following steps of mixing an inert solvent and para toluene sulfonamide, introducing phosgene at 100DEG C to 120 DEG C, feeding an inert gas for driving gas after reaction, and thus obtaining a first reaction solution; at 0 DEG C to 20 DEG C, dropwise adding tert-butylamine into the first reaction solution, heating and refluxing for 4h or more, and thus obtaining a second reaction solution; separating and purifying the second reaction solution to obtain tertiary butyl isocyanate. According to the synthesis method of tertiary butyl isocyanate, the stability and the yield of the process can be improved, and the purity of the obtained tertiary butyl isocyanate product is higher.
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Paragraph 0053-0088
(2018/09/08)
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- Reaction of N-alkyl-N′-(trimethylsilyl)carbodiimides with nitrating agents. The synthesis of N-(tert-butyl)-N′-nitrocarbodiimide
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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.
- Churakov,Ioffe,Voronin,Tartakovsky
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- A single isocyanate preparation method and system (by machine translation)
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The invention relates to a single-isocyanate preparation method and system, the method using an excess of phosgene with the corresponding [...] phosgenation reaction, the obtained reaction solution through the mentioned after the hydrogen chloride escapes the carbonyl chloride, phosgene with the isocyanate to realize the complete separation of, excess phosgene can achieve the goal of recycling. In the phosgene escapes after cracking of the reaction liquid obtained by the pyrolysis gas inert solvent for [...], obtaining the corresponding isocyanate solution, follow-up separation can obtain the qualified isocyanate. The method for preparing the single isocyanate process with high yield and low solid the characteristics of the product waste. (by machine translation)
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Paragraph 0081; 0082; 0084
(2018/06/15)
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- Synthesis method of tert-butyl isocyanate
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The invention relates to a synthesis method of tert-butyl isocyanate. The synthesis method comprises following steps: (1) evenly mixing a proper amount of catalyst and a solvent (90% of the theoretical amount) at a temperature of 90-180 DEG C to obtain a premixed solution, gradually dropwise adding a fed-batch solution into the premixed solution, after addition, maintaining the temperature of reaction solution in a range of 90-180 DEG C, keeping a reflux state, and carrying out reactions for 15 to 25 hours under stirring; and (2) after the reactions (1), delivering the mixed solution to a rotary evaporator, carrying out rotary evaporation, washing, and drying to obtain a tert-butyl isocyanate product. According to the synthesis method, tert-butyl amino formyl chloride directly carries outreactions in an inert solvent to prepare tert-butyl isocyanate; the safety hazard is radically inhibited from the source of the technology, and the preparation method has the advantages of reasonabletechnology, safety, high yield, and low production cost, and does not generate any wastewater, waste gas, or waste solid.
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Paragraph 0008; 0023-0028
(2018/11/04)
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- Industrial synthesis method of tert-butyl isocyanate
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The invention relates to an industrial synthesis method of tert-butyl isocyanate. In the presence of a catalyst and an inhibition decomposing agent, the metal cyanate and catalyst not completely reacting in the reaction process of three-level alkyl halide and metal cyanate return to the system for further reaction, thus unit consumption of the metal cyanate and catalyst is greatly reduced, the yield of waste salt is remarkably lowered, and the feasibility of the technology in industrial production of tert-butyl isocyanate is improved.
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Paragraph 0018; 0019; 0020; 0021; 0022; 0023; 0024-0027
(2017/06/02)
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- Amicarbazone synthesis method
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The invention discloses an amicarbazone synthesis method, which comprises: synthesizing tert-butyl isocyanate; synthesizing 5-methyl-1,3,4-oxadiazol-2(3H)-one; synthesizing 4-amino-3-isopropyl-5-oxo-1-H-1,2,4-triazole (triazolinone); adding hydrazine hydrate and a second NaOH solution to a third reactor, uniformly stirring, heating to a temperature of 90-100 DEG C, adding the prepared 5-methyl-1,3,4-oxadiazol-2(3H)-one in a dropwise manner, carrying out a reaction after completing the adding, cooling to a room temperature, adding a second solvent, adjusting the pH value to a neutral pH value, freezing for 2-2.5 h, filtering, washing the filter cake, re-crystallizing, and drying to obtain triazolinone; and synthesizing the amicarbazone, wherein triazolinone, potassium hydroxide, a second catalyst and a third solvent are added to a fourth reactor, the prepared tert-butyl isocyanate is added in a dropwise manner, and a heating reaction is performed to obtain the amicarbazone. According to the present invention, the synthesis method has advantages of mild reaction conditions, no requirement of special equipment, good economy, high total yield and good industrial prospect.
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Paragraph 0016; 0017; 0018
(2017/10/07)
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- Metal-Mediated Production of Isocyanates, R3EN=C=O from Dinitrogen, Carbon Dioxide, and R3ECl
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A highly efficient and versatile chemical cycle has been developed for the production of isocyanates through the molecular fixation of N2, CO2 and R3ECl (E=C, Si, and Ge). Key steps include a 'one-pot' photolytic N-N bond cleavage of a Group6 dinuclear dinitrogen complex with insitu trapping by R3ECl to provide a metal terminal imido complex that can engage in simultaneous nitrene-group transfer and oxygen-atom transfer to generate an intermediate metal terminal oxo complex with release of the isocyanate product. Reaction of the oxo complex with additional equivalents of R3ECl regenerates a metal dichloride that is the precursor for dinuclear dinitrogen starting material.
- Keane, Andrew J.,Farrell, Wesley S.,Yonke, Brendan L.,Zavalij, Peter Y.,Sita, Lawrence R.
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supporting information
p. 10220 - 10224
(2015/09/01)
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- Catalytic production of isocyanates via orthogonal atom and group transfers employing a shared formal group 6 M(II)/M(IV) redox cycle
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Under an atmosphere of CO, the Mo(IV) imido complex CpMo[N( iPr)C(Me)N(iPr)](NSiMe3) (Cp* = η5-C5Me5) (1) serves as a catalyst for production of an isocyanate via metal-mediated nitrene group transfer in benzene solution under mild conditions (55 °C, 10 psi) according to RN3 + CO → N2 + RNCO. Mechanistic and structural studies support a catalytic cycle for nitrene group transfer involving formal Mo(II) monocarbonyl and Mo(IV) (κ2-C,N)-isocyanate intermediates. These results complement an earlier finding that catalytic production of isocyanates can alternatively proceed through oxygen-atom transfer and an isomeric Mo(IV) (κ2-C,O)-isocyanate according to N2O + CNR → N2 + RNCO.
- Yonke, Brendan L.,Reeds, Jonathan P.,Fontaine, Philip P.,Zavalij, Peter Y.,Sita, Lawrence R.
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supporting information
p. 3239 - 3242
(2014/08/05)
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- (Tosylimino)phenyl-λ3-iodane as a reagent for the synthesis of methyl carbamates via hofmann rearrangement of aromatic and aliphatic carboxamides
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A new, mild procedure for the Hofmann rearrangement of aromatic and aliphatic carboxamides using (tosylimino)phenyl-λ3-iodane, PhINTs, as a reagent is reported. Because of the mild reaction conditions, this method is particularly useful for the Hofmann rearrangement of substituted benzamides, which usually afford complex reaction mixtures with other hypervalent iodine oxidants. The mild reaction conditions and high selectivity in the reaction of carboxamides with PhINTs allow the isolation of the initially formed labile isocyanates or their subsequent conversion to stable carbamates by treatment with alcohols.
- Yoshimura, Akira,Luedtke, Matthew W.,Zhdankin, Viktor V.
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experimental part
p. 2087 - 2091
(2012/05/05)
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- Trifluoroacetic anhydride-catalyzed oxidation of isonitriles by DMSO: A rapid, convenient synthesis of isocyanates
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A smooth and efficient oxidation of isonitriles to isocyanates by sulfoxides is catalyzed by trifluoroacetic anhydride. With use of DMSO as the oxidant and 5 mol·% TFAA (dichloromethane, -60 to 0 °C), the process is complete in a few minutes, forming dimethyl sulfide as the only byproduct. The newly formed isocyanates may be used directly or isolated in high purity by solvent evaporation.
- Le, Hoang V.,Ganem, Bruce
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supporting information; experimental part
p. 2584 - 2585
(2011/06/25)
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- 1-acylsemicarbazides by ring opening of iminodiaziridines with carboxylic acids: Novel, expeditious access to the azapeptide motif
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Carboxylic acids react rapidly and quantitatively with iminodiaziridines to afford 1,2,4-trisubstituted 1-acylsemicarbazides in a multistep sequence. In this way, a carboxy group is readily converted into an azapeptide motif. Broad signals in high-field H and C NMR spectra recorded for the products are indicative of dynamic processes. Georg Thieme Verlag Stuttgart New York.
- Quast, Helmut,Schmitt, Edeltraud,Ross, Karl-Heinz
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experimental part
p. 3358 - 3362
(2010/11/16)
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- Carbonyldiimidazole-mediated lossen rearrangement
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[Chemical Equation Presented] Carbonyldiimidazole (CDI) was found to mediate the Lossen rearrangement of various hydroxamic acids to isocyanates. This process is experimentally simple and mild, with imidazole and CO 2 being the sole stoichiometric byproduct. Significant for large-scale application, the method avoids the use of hazardous reagents and thus represents a green alternative to standard processing conditions for the Curtius and Hofmann rearrangements.
- Dube, Pascal,Fine Nathel, Noah F.,Vetelino, Michael,Couturier, Michel,Aboussafy, Claude Larrivee,Pichette, Simon,Jorgensen, Matthew L.,Hardink, Mark
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supporting information; experimental part
p. 5622 - 5625
(2010/03/02)
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- Dicyclooctane Derivatives, Preparation Processes and Medical Uses Thereof
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The present invention relates to new dicyclooctane derivates represented by general formula (I), preparation processes and pharmaceutical compositions containing them, and to uses for treatment especially for dipeptidyl peptidase inhibitor (DPPIV), in which each substituent group of general formula (I) is as defined in specification.
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Page/Page column 23
(2009/07/18)
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- Synthesis and evaluation of structurally constrained imidazolidin derivatives as potent dipeptidyl peptidase IV inhibitors
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To find potent and selective inhibitors of dipeptidyl peptidase IV (DPP-IV), we synthesized a series of 2-cyanopyrrolidine derivatives with constrained imidazolidin ring and tested their activities against DPP-IV. Most of them exhibited submicromolar inhibitory activities against DPP-IV. The most potent compound among these is (S)-1-(2-(2-(3-(3,4-dimethoxyphenyl)-2-oxoimidazolidin-1-yl)ethyl-amino)acetyl)pyrrolidine-2-carbonitrile (6n), which is a 2 nM DPP-IV inhibitor.
- Wang, Liutang,Zhang, Bin,Ji, Jianxin,Li, Bogang,Yan, Jufang,Zhang, Weiyu,Wu, Yong,Wang, Xuechao
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experimental part
p. 3318 - 3322
(2009/12/01)
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- Synthesis and structure of N-alkyl(aryl)aminocarbonyl-1,4-benzoquinone imines
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New N-alkyl(aryl)aminocarbonyl-1,4-benzoquinone imines were synthesized by reaction of isocyanates with the corresponding substituted 4-aminophenols, and their structure was determined on the basis of 1H and 13C NMR spectra and X-ray diffraction data.
- Avdeenko,Konovalova,Sergeeva,Zubatyuk,Palamarchuk,Shishkin
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experimental part
p. 1765 - 1772
(2009/09/05)
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- DICYCLOOCTANE DERIVATES, PREPARATION PROCESSES AND MEDICAL USES THEREOF
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The present invention relates to new dicyclooctane derivates represented by general formula (I), preparation processes and pharmaceutical compositions containing them, and to uses for treatment especially for dipeptidyl peptidase inhibitor (DPPIV), in which each substituent group of general formula (I) is as defined in specification
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Page/Page column 29
(2009/01/24)
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- Oxo and imido/imido exchange and C-H activation reactions based on pentamethylcylopentadienyl imido tantalum complexes
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Reactions of [TaCp*Cl4] with two, three and four equivalents of LiNHtBu give the halo- and amido-imido complexes [TaCp*Cl2(NtBu)] (1a), [TaCp*Cl(NtBu)(NHtBu)] (2) and [TaCp*(NtBu)(NHtBu)2] (3), respectively. The related complex [TaCp*Cl2{N(2,6-Me2C6H3)}] (1b) is prepared by a similar reaction using two equivalents of Li[NH(2,6-Me2C6H3)]. Complex 3 can be transformed into 2 and further into 1a by reaction with SiClMe3. Complex 1a reacts with CNtBu to give the 18-electron adduct [TaCp*Cl2(NtBu)(CNtBu)] (4) whereas addition of excess CN(2,6-Me2C6H3) results in reductive elimination of the carbodiimide tBuN=C=N(2,6-Me2C6H3) (5) to give [TaCp*Cl2{CN(2,6-Me2C6H 3)}3]. However complex 1b does not react with any of the isocyanide ligands. Both complexes 1a and 1b react with PhCHO undergoing imido/oxo exchange to give the imines PhCH=NR (R=tBu, 2,6-Me2C6H3 (6)) and dimeric [TaCp*Cl2(O)]2 or trimeric [(TaCp*Cl)3(μ2-Cl)(μ2-O) 3(μ3-O)] oxo-complexes, whereas only 1a reacts with CO2, PhCH=NR′ (R′=Ph, Me) and (2,6-Me2C6H3)N=C=NtBu producing tBuN=CO, PhCH=NtBu and tBuN=C=NtBu, respectively and the corresponding oxo or imido tantalum derivative. None of the complexes reacts with CO or NCR (R=Me, Ph). The complex [TaCp*Me(NtBu)(NHtBu)] activates C-H bonds when heated in benzene and toluene affording [TaCp*Ph(NtBu)(NHtBu)] (7) and a mixture of [TaCp*(m-MeC6H4)(NtBu)(NHtBu)] 8a and [TaCp*(p-MeC6H4)(NtBu)(NHtBu)] (8b). All of the reported organic compounds and tantalum complexes were characterized by 1H- and 13C-NMR spectroscopy.
- Royo, Pascual,Sánchez-Nieves, Javier
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- Preparation of isocyanates from primary amines and carbon dioxide using Mitsunobu chemistry
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Primary alkylamines 1 and hindered arylamines 1 give high yields of isocyanates 5 when reacted with carbon dioxide and the Mitsunobu zwitterions 4 generated from dialkyl azodicarboxylates and Bu3P in dichloromethane at - 78°C. Use of Ph3P still gave high yields of isocyanates from reactions of primary alkylamines, but only low yields were obtained from reactions of aromatic amines. Reactions which failed to give high yields of isocyanates gave either carbamoylhydrazines 6 and/or dicarbamoylhydrazines 10 and/or triazolinones 7. The triazolinones were shown to arise from reactions of reactive aryl isocyanates with the Mitsunobu zwitterion. The carbamoylhydrazines were shown not to arise from reaction of isocyanate with reduced dialkyl azodicarboxylates, and a mechanism for their formation is proposed. Single-crystal X-ray analyses confirmed the structures of 6, 7, and 10.
- Saylik, Dilek,Horvath, Michael J.,Elmes, Patricia S.,Jackson, W. Roy,Lovel, Craig G.,Moody, Keith
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p. 3940 - 3946
(2007/10/03)
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- A Mitsunobu-based procedure for the preparation of alkyl and hindered aryl isocyanates from primary amines and carbon dioxide under mild conditions
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A Mitsunobu-based procedure for the preparation of alkyl and hindered aryl isocyanates in excellent yields from primary amines and carbon dioxide under very mild conditions is described.
- Horvath,Saylik,Elmes,Jackson,Lovel,Moody
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p. 363 - 366
(2007/10/03)
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- Synthesis and antibacterial activity of 4-ureido trinems
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This article describes studies carried out on the synthesis and biological activity of 4-ureido trinems 1 obtained by the condensation of various isocyanates and the intermediate 6. Among others, 4-N-methyl-N'-alkyl ureido trinems showed a promising antimicrobial activity against Gram-negative bacteria.
- Gehanne, Sylvie,Piga, Elisabetta,Andreotti, Daniele,Biondi, Stefano,Pizzi, Domenica
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p. 2791 - 2794
(2007/10/03)
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- Reactivity of Carbamoyl Radicals. A New, General, Convenient Free-Radical Synthesis of Isocyanates from Monoamides of Oxalic Acid
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A new, general, simple synthesis of isocyanates was developed by oxidation of monoamides of oxalix acid with peroxydisulfate catalyzed by Ag and Cu salts.The reaction was carried out in a two-phase system (water and an organic solvent), and it is suitable also for practical applications, due to the simple experimental conditions and the inexpensive as well as nontoxic reagents.The first example of homolytic intramolecular aromatic carbamoylation is also reported.
- Minisci, Francesco,Fontana, Francesca,Coppa, Fausta,Yan, Yong Ming
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p. 5430 - 5433
(2007/10/02)
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- Neue Methode zur Synthese von Isocyanaten unter milden Bedingungen
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Keywords: Arendiyldiisocyanate; Di-tert-butyldicarbonat; 4-Dimethylaminopyridin; Isocyanate
- Knoelker, Hans-Joachim,Braxmeier, Tobias,Schlechtingen, Georg
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p. 2746 - 2749
(2007/10/03)
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- Reactivity of Carbamoyl Radicals: the First General and Convenient Free-radical Synthesis of Isocyanates
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The first free-radical synthesis of isocyanates was performed by oxidation of oxalic acid monoamides by S2O82-, catalysed by silver(I) and copper(II) salts, in a two-phase system.
- Minisci, Francesco,Coppa, Fausta,Fontana, Francesca
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p. 679 - 680
(2007/10/02)
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- Isocyanates and their preparation using hypochlorous acid
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The present invention relates to a process for preparation of an isocyanate comprising (a) reacting an amide with an aqueous solution of hypochlorous acid in the presence of an water-immiscible organic solvent to produce an N-chloro amide; and (b) reacting said N-chloro amide with a base in the presence of a phase transfer catalyst and a water immiscible organic solvent to produce an isocyanate.
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- THE PHOTOCHEMISTRY OF 1,4-DIHYDRO-5H-TETRAZOLE DERIVATIVES ISOLATED IN LOW-TEMPERATURE MATRICES
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Six 1,4-dihydro-5H-tetrazole (tetrazoline) derivatives have been photolysed in Ar and N2 matrices at 12 K.The dimethyltetrazolinone (1a) gave as the major product the same diaziridinone obtained previously from solution photolysis, but it also underwent a novel cleavage to MeNCO and, presumably, methyl azide.Iminotetrazolines (3a) and (3b) gave the corresponding carbodiimides (5a) and (5b), and iminodiaziridines (4a) and (4b); while the tetrazolinethiones (7a) and (7b) gave carbodiimides (8a) and (8b), respectively.Photolysis of the vinyl substituted tetrazolinone (9) proceeded differently in inert ambient-temperature solutions and low-temperature matrices.In the former an imidazolone (10) was the sole isolable product, while in the latter formation of diaziridinone (15) competed with an alternative cleavage giving t-butyl isocyanate and vinyl azide.THese results are best interpreted on the basis of an intermediate biradical, which, however, could not be detected directly by matrix ir. spectroscopy.
- Dunkin, Ian R.,Shields, Charles J.
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p. 259 - 268
(2007/10/02)
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- Alkylation of Nitrocyanamide. A New Synthesis of Isocyanates
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Thirteen alkyl halides (primary, secondary, and tertiary aliphatic including alicyclic, aralkyl, and heteroalkyl systems) and certain non-vicinal dihalides on treatment with silver nitrocyanamide are converted into the corresponding isocyanates (63-95percent).Intermediate alkylnitrocyanamides, spectroscopically detected, thermolysed (-20-80 deg C) to the expected isocyanates.In certain examples silver nitrocyanamide is generated in situ from sodium nitrocyanamide and silver nitrate.Silver nitrocyanamide does not react with cyclopropyl bromide, acetyl chloride, toluene-p-sulphonyl chloride, phenacyl bromide and 2-bromomethyldioxolane (27), and the ethylene acetal (28) of 1-bromo-4-iodopentacyclo-nonan-9-one.Silver nitrocyanamide reacts with 4,6-bis(bromomethyl)-3,7-dimethyl-1,5-diazabicyclo3.3.0)octane-2,8-dione (26), to give an intractable mixture.Vicinal dihalides give erratic results without detectable formation of vicinal di-isocyanates: unisolated 2-bromoethyl isocyanate (tentative assignment) has been detected in a product mixture from ethylene dibromide; an expected rearrangement during the reaction with 1,2-dibromocyclobutane, brought about the formation of 4-bromobut-3-enyl isocyanate isolated as ethyl 4-bromobut-3-enylcarbamate in low yield; and 1,2-dibromocyclohexane gives 2-bromocyclohexyl isocyanate isolated as ethyl N-(2-bromocyclohexyl)-carbamate in low yield.
- Boyer, Joseph H.,Manimaran, Thanikavelu,Wolford, Lionel T.
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p. 2137 - 2140
(2007/10/02)
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- Kinetics of the Decomposition of Aliphatic Acyl Azides
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The kinetics of the decomposition of a series of aliphatic acyl azides have been investigated.The first-order rate constants and activation parameters have been determined and the influence of the substituents and of solvent polarity on the rate of decomposition has been established.
- Zlobin, V. A.,Tarasov, A. K.
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p. 140 - 141
(2007/10/02)
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- Preparation of isocyanates and/or derivatives thereof
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Isocyanates and derivatives thereof are prepared by oxidative conversion of compounds having at least one group STR1 wherein X represents OY or STR2 wherein Y is H, a metal ion or group NR3 R4 R5 R6 wherein each of R3, R4, R5 and R6 which may be the same or different, is H, alkyl or (substituted) (alk)aryl and Z is a (substituted) alkyl or aryl group. Phenyl isocyanate and derivatives thereof are preferably prepared electrochemically from the corresponding oxamides and oxanilides.
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- Chemiluminescence of Imino-1,2-dioxetan Formed from Ketenimine and Singlet Oxygen
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The chemiluminescent properties of several imino-1,2-dioxetans prepared by the photosensitized oxygenation of ketenimines at -78 degC, indicate that the energy level of the transition state for their decomposition to the corresponding ketones and isocyanates is low and that the decomposition proceeds via a biradical mechanism.
- Ito, Yoshikatsu,Yokoya, Hiroaki,Kyono, Kazuaki,Yamamura, Soichiro,Yamada, Yutaka,Matsuura, Teruo
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p. 898 - 900
(2007/10/02)
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- Preparation of organic isocyanates
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A process for the manufacture of organic isocyanates which comprises reacting a substituted urea having at least one unsubstituted NH2 group with nitrous acid in the presence of a water-immiscible solvent and a phase transfer agent.
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- N-[2-(pyridinyl)-4-pyrimidinyl]ureas
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Compounds useful as anti-allergic agents are N-R3 -N-R4 -N'-R-N'-(2-Q-5-R1 -6-R2 -4-pyrimidinyl)ureas (I), where Q is 4- or 3- or 2-pyridinyl or 4- or 3- or 2-pyridinyl having one or two lower-alkyl substituents or N-oxide thereof, R is hydrogen or lower-alkyl, R1 is hydrogen, lower-alkyl or cyano, R2 is hydrogen or lower-alkyl, R3 is hydrogen, lower-alkyl or lower-hydroxyalkyl, R4 is hydrogen, lower-alkyl, lower-hydroxyalkyl, lower-alkenyl or lower-cycloalkyl. Said ureas are prepared by reacting 2-Q-4-RNH-5-R1 -6-R2 -pyrimidine (II) with a carbamylating agent selected from an R4 '-isocyanate of the formula R4 'N=C=O to produce N-R4 '-N'-R-N'-(2-Q-5-R1 -6-R2 -4-pyrimidinyl)urea (IA), an N-R3 '-N-R4 '-carbamyl halide of the formula R3 'R4 'NC(=O)-halide to produce N-R3 '-N-R4 'N'-R-N'-(2-Q-5-R1 -6-R2 -4-pyrimidinyl)urea (IB) or 1,1'-carbonyldiimidazole to produce N-(2-Q-5-R1 -6-R2 -4-pyrimidinyl)-N-R-imidazole-1-carboxamide and then reacting said 1-carboxamide with R3 R4 NH to produce I.
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