- Synthesis of Lepadiformine Using a Hydroamination Transform
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Dissection of lepadiformine by a double hydroamination transform affords a simple achiral amino diene. This reaction is accomplished in the forward sense by amine-directed hydroboration and an oxidative alkyl shift to nitrogen, both of which occur with hi
- Tabor, M. Greg,Shenvi, Ryan A.
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- New synthesis, properties, and oxidizing ability of 1,3-dimethyl-5,10- methanocycloundeca[4,5]furo[2,3-d]pyrimidin-2,4(1,3H)-dionylium tetrafluoroborate
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A novel synthesis of 1,3-dimethyl-5,10-methanocycloundeca[4,5]furo[2,3-d] pyrimidin-2,4(1,3H)-dionylium tetrafluoroborate (10+·BF 4-) was accomplished by the reaction of 3,8-methano[11]-annulenone with dimethylbarbituric acid and following acidic cyclization, albeit in low yield. Remarkable structural characteristics were suggested on inspection of the spectral data and MO calculation, and it was clarified that the positive charge is largely localized at the C11. The pK R+ value of cation 10+ was determined spectrophotometrically to be 4.6, which is much smaller by 4.1 pH unit than that of 1,3-dimethyl-7,12-methanocycloundeca[4,5]furo[2,3-d]pyrimidin-2,4(1,3H)- dionylium tetrafluoroborate (pKR+ = 8.7). This value is also smaller by 1.6 pH unit than that of the parent 1,6-methano[11]annulenylium ion (pK R+ = 6.2). The feature is rationalized on the basis of the perturbation derived from the bond fixation of the parent cation. The electrochemical reduction of 10+ exhibited less negative reduction potential at -0.39 (V vs Ag/AgNO3) upon cyclic voltammetry (CV). In a search for reactivity, reactions of 10+ with some nucleophiles, hydride and diethylamine, were carried out to give mixtures of C11- and C13-adducts. In both reactions, the methano-bridge controls the nucleophilic attacks to the C13 to favor exo selectivity. The photoinduced autorecycling oxidation reactions of 10+·BF4- toward some amines under aerobic conditions were carried out to give the corresponding imines (isolated by converting to the corresponding 2,4-dinitrophenylhydrazones) in 719-3286% yield (recycling number of 10+·BF 4-: 7.2-32.9).
- Naya, Shin-Ichi,Warita, Masato,Mitsumoto, Yuhki,Nitta, Makoto
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- Reductive amination of cyclohexanone in the presence of cyclohexanol over zeolites Hβ and HY
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Reductive amination of a mixture of cyclohexanone/cyclohexanol in varying proportions has been carried out in the gas phase over zeolites Hβ and HY. The products identified were cyclohexylamine, N-cyclohexylcyclohexanimine, 2-cyclohexen-1-ylcyclohexanone and 2-cyclohexylcyclohexanone. The product distribution during the experiments indicates that cyclohexanol does not undergo reductive amination over acid catalysts; it only forms a condensation product with cyclohexanone. The reaction rates were obtained from experimental data and fit to a kinetic model derived for this reaction. The fits show that this reaction follows a Langmuir-Hinshelwood pathway by the adsorption of both cyclohexanone and the NH3 on the surface of the zeolite.
- Kirumakki, Sharath R.,Papadaki, Maria,Chary, Komandur V.R.,Nagaraju
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- Synthesis of 5-cyclodecenones via RCM and a three-pot sequence for bisannulation
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5-Cyclodecenones were made by RCM, using the first generation Grubbs catalyst and infinite dilution in refluxing dichloromethane. A convenient one-pot procedure for making 2,6-disubstituted cyclohexanones was developed, which allowed for the synthesis of
- Curton, Nicholas,Ornelas, Joel,Uhrinak, Abby,Rhem, Brittney,Coulter, Jess,Zhang, Joe,Joyner, P. Matthew,White, James B.
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- NHC-assisted Ni(II)-catalyzed acceptorless dehydronation of amines and secondary alcohols
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A novel catalytic system including NiCl2-NHC ligand precursor has been developed for the preparation of imines from amines and ketones from alcohols. Owing to the acceptorless dehydrogenation pathway for this reaction, the hydrogen gas is liberated as a by-product. The active catalyst is generated in situ by the reaction of nickel (II) chloride, bis (imidazolium) chlorides and potassium tert-butoxide. The products were obtained in good to excellent yields and a wide variety of amines and ketones were applied successfully in this protocol.
- Takallou, Ahmad,Habibi, Azizollah,Halimehjan, Azim Ziyaei,Balalaie, Saeed
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- Supported gold-palladium alloy nanoparticle catalyzed tandem oxidation routes to N-substituted anilines from non-aromatic compounds
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In the presence of a supported gold-palladium alloy nanoparticle catalyst (Au-Pd/Al2O3), various kinds of N-substituted anilines can be synthesized from non-aromatic compounds. The observed catalysis is truly heterogeneous, and Au-Pd/Al2O3 can be reused without a significant loss of its catalytic performance.
- Taniguchi, Kento,Jin, Xiongjie,Yamaguchi, Kazuya,Mizuno, Noritaka
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- First total synthesis of (+)-broussonetine W: Glycosidase inhibition of natural product & analogs
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The first total synthesis of (+)-broussonetine W (4), a naturally-occurring pyrrolidine iminosugar isolated from the traditional Chinese medical plant Broussonetia kazinoki SIEB (Moraceae), has been completed through a concise synthetic route starting from the readily available d-arabinose derived cyclic nitrone 10 in 11 steps and 31% overall yield, with regioselective installation of the α,β-unsaturated ketone functional group by the elimination of HBr from α-bromoketone as the key step. A number of analogs of (+)-broussonetine W (4) with variable side chain length, different polyhydroxylated pyrrolidine core configurations or saturated cyclohexanones have also been prepared to explore the glycosidase inhibition and the preliminary structure-activity relationship of this intriguing class of compounds. Glycosidase inhibition studies identified the natural product (+)-broussonetine W (4) as a selective and potent inhibitor of β-galactosidase (IC50 = 0.03 μM), while its enantiomer was a selective and potent inhibitor of α-glucosidase (IC50 = 0.047 μM). It was found that the configuration of the polyhydroxylated pyrrolidine ring played a key role on their glycosidase inhibitory activities. The length of side chain and α,β-unsaturated ketone functional group also exhibited some effect on their glycosidase inhibition.
- Song, Ying-Ying,Kinami, Kyoko,Kato, Atsushi,Jia, Yue-Mei,Li, Yi-Xian,Fleet, George W. J.,Yu, Chu-Yi
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- Co-N-C supported on SiO2: A facile, efficient catalyst for aerobic oxidation of amines to imines
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We developed a novel, facile preparation method of Co-N-C/SiO2, which was the pyrolysis of silicone gel containing metal ion and triethanolamine (TEA) prepared by sol-gel process. N2 adsorption-desorption characterization displayed the sample had high specific surface area and pore volume (220.9 m2 g-1, 0.67 mL g-1). The active Co appeared to be small particles with size of about 5 nm and was well dispersed on SiO2. And the highly dispersed cobalt and nitrogen-doped carbon in Co-N-C/SiO2 served as active phase for the oxidation of amines to imines, thus Co-N-C/SiO2 could efficiently catalyze the oxidation of amines to imines in solvent-free, air atmospheric conditions, avoiding the use of large excesses of additives, specialized oxidant and solvent.
- Zhang, Chenghui,Zhao, Pengshan,Zhang, Zongliang,Zhang, Jingwei,Yang, Ping,Gao, Peng,Gao, Jun,Liu, Di
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- Azobisisobutyronitrile initiated aerobic oxidative transformation of amines: Coupling of primary amines and cyanation of tertiary amines
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In the presence of a catalytic amount of radical initiator AIBN, primary amines are oxidatively coupled to imines and tertiary amines are cyanated to α-aminonitriles. These "metal-free" aerobic oxidative coupling reactions may find applications in a wide
- Liu, Lianghui,Wang, Zikuan,Fu, Xuefeng,Yan, Chun-Hua
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- Mechanistic study on the ruthenium-catalyzed direct amination of alcohols
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The Ru-catalyzed direct amination of alcohols with ammonia was investigated for the RuHCl(CO)(PPh3)3/Xantphos system in order to gain mechanistic insight. For several Ru(II) precursor complexes the influence of different additives on catalytic performance was investigated. NMR studies revealed that the reaction of RuHCl(CO)(PPh3)3/Xantphos with the alcohol in the presence of a strong base initially formed an inactive dihydrido Ru species. However, by addition of a ketone, the dihydride was (re)activated, where the corresponding imine is the actual activator, formed by immediate condensation of the ketone with ammonia. In the absence of a base, added ketone significantly enhanced catalyst activity. Catalytically inactive RuCl2(PPh3)3 could be activated by base, demonstrating that also complexes without the CO ligand give active catalysts. On the basis of these observations a mechanism was proposed, closely related to known transfer hydrogenation mechanisms.
- Pingen, Dennis,Lutz, Martin,Vogt, Dieter
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- Charge-reversal Mass Spectra of Enolate Ions of Some Open-chain and Cyclic Ketones for Structure Identification
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The charge-reversal (CR) mass spectra of the enolate ions of heptanal and ten isomeric heptanones, of cyclohexanone, of cycloheptanone, of isomeric methylcyclohexanones, of isomeric ethylcyclohexanones and of the isomeric monoterpene ketones camphor, fenchone, pulegone and thujone were obtained by deprotonating using OH(-) under chemical ionization conditions followed by collision of the (-) ions with helium in the second field-free region of a VG ZAB 2F mass spectrometer.The CR mass spectra were evaluated by similarity index (SI) values.Characteristic of the CR mass spectra of the open-chain enolates are fragment ions formed by α- cleavage.However, the CR mass spectra are dominated by peaks of small hydrocarbon ions, particularly in the case of cyclic and bicyclic enolates.The CR mass spectra of enolates of linear heptanones differing in the position of the carbonyl group can be easily correlated with the structure of the parent ketone.The CR mass spectra of enolates of isomeric heptan-2-ones differing only in the degree of branching of the alkyl group are similar, but can be distinguished by the SI values.The CR mass spectra of the enolates of the isomeric cyclic and bicyclic ketones studied are more or less identical and cannot be used for structural assignment.
- Suerig, Thomas,Gruetzmacher, Hans-Friedrich
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- Polycondensation of boron- and nitrogen-codoped holey graphene monoliths from molecules: Carbocatalysts for selective oxidation
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A simple but powerful chemical process - the copolymerization of biomass (glucose) and boric acid as templated by dicyandiamide (see picture) - was used to fabricate high-quality doped graphene monoliths with through-plane nanopores. The holey graphene mo
- Li, Xin-Hao,Antonietti, Markus
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- Can molecular sieves be used as water scavengers in microwave chemistry?
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The use of sealed-vessel microwave-assisted organic synthesis in combination with 4 molecular sieves as water scavengers is investigated. Two classical model transformations, namely acetal formation and imine formation, are evaluated under both convention
- Baghbanzadeh, Mostafa,Kappe, C. Oliver
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- A remarkable solvent effect on reductive amination of ketones
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We report the first systematic study of solvent effect on reductive amination of ketones with ammonia and dihydrogen (H2) over Ru/C, Rh/C, Pd/C and Pt/C catalysts. Protic (water, methanol, ethanol and isopropanol), aprotic polar (dioxane and tetrahydrofuran) and aprotic apolar (cyclohexane and toluene) solvents were investigated. Reaction kinetic model was built to reveal solvent-dependent reaction pathway and solvent-related rate constant for individual steps. Primary amine is produced via two distinct routes, i.e., hydrogenation of imine and hydrogenolysis of Schiff base adduct. These two routes co-exist in organic solvents, while the preference of which route to take heavily depends on the nature of the solvent. In contrast, the formation of imine and Schiff base are not favored in water, resulting in high selectivity towards alcohol. Methanol is identified as the best solvent for reductive amination of ketones, attributed to the highest rates for imine and Schiff base formation compared to other solvents, as well as high hydrogenation activity.
- Song, Song,Wang, Yunzhu,Yan, Ning
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- Preparation method of cyclohexanone oxime
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The invention relates to a preparation method of cyclohexanone oxime. The method comprises the following steps: carrying out partial oxidation reaction on cyclohexylamine and molecular oxygen under the action of a catalyst to obtain an oxidation reaction product consisting of cyclohexanone oxime, a byproduct and possibly unconverted cyclohexylamine; and then treating the oxidation reaction product in one of the following modes: (i) carrying out hydrogenation amination reaction with H2 and NH3 at the same time or carrying out hydrogenation and amination reaction in sequence under the action of a catalyst without separation or after part or all of water in the oxidation reaction product is separated, and then carrying out separation to obtain cyclohexanone oxime; and (ii) carrying out hydrogenation reaction with H2 under the action of a catalyst without separation or after part or all of water is separated out, and then carrying out separation to obtain the cyclohexanone oxime. The method disclosed by the invention has the characteristics of short process flow, small occupied area and investment, low material consumption and energy consumption (low cost), simplicity and convenience in operation, environment friendliness and the like.
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Paragraph 0067-0071
(2021/06/13)
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- Ambient-Temperature Synthesis of Primary Amines via Reductive Amination of Carbonyl Compounds
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Efficient synthesis of primary amines via low-temperature reductive amination of carbonyl compounds using NH3 and H2 as the nitrogen and hydrogen resources is highly desired and challenging in the chemistry community. Herein, we employed naturally occurring phytic acid as a renewable precursor to fabricate titanium phosphate (TiP)-supported Ru nanocatalysts with different reduction degrees of RuO2 (Ru/TiP-x, x represents the reduction temperature) by combining ball milling and molten-salt processes. Very interestingly, the obtained Ru/TiP-100 had good catalytic performance for the reductive amination of carbonyl compounds at ambient temperature, resulting from the synergistic cooperation of the support (TiP) and the Ru/RuO2 with a suitable proportion of Ru0 (52%). Various carbonyl compounds could be efficiently converted into the corresponding primary amines with high yields. More importantly, the conversion of other substrates with reducible groups could also be achieved at ambient temperature. Detailed investigations indicated that the partially reduced Ru and the support (TiP) were indispensable. The high activity and selectivity of Ru/TiP-100 catalyst originates from the relatively high acidity and the suitable electron density of metallic Ru0.
- Xie, Chao,Song, Jinliang,Hua, Manli,Hu, Yue,Huang, Xin,Wu, Haoran,Yang, Guanying,Han, Buxing
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p. 7763 - 7772
(2020/08/21)
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- AlCl3 immobilized on silicic acid as efficient Lewis acid catalyst for highly selective preparation of dicyclohexylamine from the vapor phase hydroamination of cyclohexene with cyclohexylamine
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An efficient and stable Lewis acid catalyst silicic acid (SA)-immobilized AlCl3 (AlCl3-SA) has been successfully prepared by the chemical bonding method in this work. The results indicated that the immobilized 15percentAlCl3-SA exhibited excellent catalytic performance and stability in the vapor phase hydroamination of cyclohexene with cyclohexylamine. 58.5percent cyclohexene conversion with 98.7percent selectivity to dicyclohexylamine was still maintained after running for over 150 h, and the space time yield of dicyclohexylamine was 142.6 mol/h·m3. The developed AlCl3-SA catalyst had the advantages of low cost and long-time stable activity. Maybe this work provides a promising approach for hydroamination of olefins to amines.
- Ai, Qiuhong,Jian, Jian,Liu, Pingle,Luo, He'an,Wen, Jingbin,You, Kuiyi,Zhao, Fangfang
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- Pd/C Catalyzed selective hydrogenation of nitrobenzene to cyclohexanone oxime in the presence of NH2OH·HCl: Influence of the operative variables and insights on the reaction mechanism
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We studied the influence of temperature, solvent, pressure, catalysts type on the selectivity of nitrobenzene hydrogenation to cyclohexanone oxime (COX) in the presence of NH2OH. The best reaction conditions are: pressure 0.8 MPa, temperature 333 K, solvent ethers, and catalyst Pd/C5%. Other hydrogenation metal catalysts did not give comparable results. The amount of Pd/C influences the yield in COX, which rises above to 90 % at the highest load. The reaction profile shows that aniline is the reaction intermediate. Indeed, aniline as a substrate gives COX, though in lower yield than that achieved employing nitrobenzene. The NH2OH parallel hydrogenation to NH4Cl, influences positively the selectivity to COX. It has been observed that COX, cyclohexanone and N-cyclohexylideneaniline are in equilibrium in the reaction solution and all likely derive from nucleophilic substitutions to a common imine intermediate formed on the Pd surface, whose high activity does not need any further metal catalyst.
- Pietrobon, L.,Pontello, R.,Ronchin, L.,Sadraoui, C.,Tosetto, C.,Vavasori, A.
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- Site-specific catalytic activities to facilitate solvent-free aerobic oxidation of cyclohexylamine to cyclohexanone oxime over highly efficient Nb-modified SBA-15 catalysts
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The development of highly active and selective heterogeneous catalysts for efficient oxidation of cyclohexylamine to cyclohexanone oxime is a challenge associated with the highly sensitive nitrogen center of cyclohexylamine. In this work, dispersed Nb oxide supported on SBA-15 catalysts are disclosed to efficiently catalyze the selective oxidation of cyclohexylamine with high conversion (>75%) and selectivity (>84%) to cyclohexanone oxime by O2without any addition of solvent (TOF = 469.8 h?1, based on the molar amount of Nb sites). The role of the active-site structure identity in dictating the site-specific catalytic activities is probed with the help of different reaction and control conditions and multiple spectroscopy methods. Complementary to the experimental results, further poisoning tests (with KSCN or dehydroxylation reagents) and DFT computational studies clearly unveil that the surface exposed active centers toward activation of the reactants are quite different: the surface -OH groups can catch the NH2group from cyclohexylamine by forming a hydrogen bond and lead to a more facile cyclohexylamine oxidation to desired products, while the monomeric or oligomeric Nb sites with a highly distorted structure play a key role in the dissociation of O2molecules beneficial for insertion of active oxygen species into cyclohexylamine. These catalysts exhibit not only satisfactory recyclability for cyclohexylamine oxidation but also efficiently catalyze the aerobic oxidation of a wide range of amines under solvent-free conditions.
- Ding, Wei,Mao, Liqiu,Peng, Haoyu,Yin, Dulin,Zhong, Wenzhou
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p. 3409 - 3422
(2020/06/09)
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- Metal-free nitrogen -doped carbon nanosheets: A catalyst for the direct synthesis of imines under mild conditions
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Herein, a highly stable, porous, multifunctional and metal-free catalyst was developed, which exhibited significant catalytic performance in the oxidation of amines and transfer hydrogenation of nitriles under mild conditions; this could be attributed to the presence of numerous active sites and their outstanding BET surface area. The obtained results showed that most of the yields of imines exceeded 90%, and the cycling performance of the catalyst could be at least seven runs without any decay in the reaction activity, which could be comparable to those of metal catalysts. Subsequently, a kinetic study has demonstrated that the apparent activation energy for the direct synthesis of imines from amines is 67.39 kJ mol-1, which has been performed to testify that the catalytic performances are rational. Via catalyst characterizations and experimental data, graphitic-N has been proven to be the active site of the catalyst. Hence, this study is beneficial to comprehend the mechanism of action of a metal-free N-doped carbon catalyst in the formation of imines.
- Wang, Kaizhi,Jiang, Pengbo,Yang, Ming,Ma, Ping,Qin, Jiaheng,Huang, Xiaokang,Ma, Lei,Li, Rong
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p. 2448 - 2461
(2019/05/17)
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- Cobalt-Catalyzed Dehydrogenative Coupling of Amines into Imines
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Primary amines have been subjected to an acceptorless dehydrogenative homo- and heterocoupling into imines with a cobalt catalyst. The catalytically active species are composed of cobalt nanoparticles, which are generated in situ by heating Co2(CO)8 in the presence of trioctylphosphine oxide as a surfactant. The nanoparticles have been characterized by transmission electron microscopy where the image showed spherical and small particles with a narrow size distribution. The catalyst can be recovered and used again with essentially no effect on the yield. The catalyst can also be used for the dehydrogenative coupling of alcohols and amines into imines.
- Bottaro, Fabrizio,Takallou, Ahmad,Chehaiber, Ahmad,Madsen, Robert
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supporting information
p. 7164 - 7168
(2019/11/16)
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- Small structure tree alkali compound and its preparation method and application
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The invention relates to a Broussonetia kazinoki alkaline compound. Structure of the compound is shown as a formula (1). The invention further provides a preparation method of the compound, a glycosidase inhibitor by using the compound or the compound prepared by the method as an active ingredient and application of the compound or the compound, prepared by the method, serving as an active ingredient in preparing drug. The Broussonetia kazinoki alkaline compound has high glycosidase inhibiting activity and potential medicinal value.
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Paragraph 0157
(2018/04/26)
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- Small structure tree alkali compound and its preparation method and application
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The invention relates to a Broussonetia kazinoki alkaline compound. Structure of the compound is shown as a formula (1). The invention further provides a preparation method of the compound, a glycosidase inhibitor by using the compound or the compound prepared by the method as an active ingredient and application of the compound or the compound, prepared by the method, serving as an active ingredient in preparing drug. The Broussonetia kazinoki alkaline compound has high glycosidase inhibiting activity and potential medicinal value.
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Paragraph 0120; 0122; 0129
(2018/09/26)
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- Amide: Versus amine ligand paradigm in the direct amination of alcohols with Ru-PNP complexes
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The catalytic activity of a series of Ru-PNP pincer ligand complexes was studied in the direct amination of alcohols with ammonia. It turned out that all complexes of PNP ligands bearing a secondary amine showed no activity in this hydrogen-shuttling reaction sequence, while all complexes of homologous ligands bearing a tertiary amine gave active catalysts. Further comparative studies on catalysts bearing an acridine-based PNP pincer ligand and a PNP ligand of the Xantphos family provided valuable mechanistic insight that led to the design of a highly active catalyst. It appears that in the group of ligands studied here only ligands that do not form stable Ru-amido complexes are active alcohol amination catalysts.
- Pingen, Dennis,Choi, Jong-Hoo,Allen, Henry,Murray, George,Ganji, Prasad,Van Leeuwen, Piet W. N. M.,Prechtl, Martin H. G.,Vogt, Dieter
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p. 3969 - 3976
(2018/08/16)
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- Preparation method of cyclohexanone-oxime
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The invention relates to a preparation method of cyclohexanone-oxime. The method comprises the steps of firstly preparing N-cyclohexyl hexamethyleneimine through condensation reaction of cyclohexanone and cyclohexylamine as raw materials; and catalytically oxidizing the N-cyclohexyl hexamethyleneimine by employing molecular oxygen as an oxidizing agent under the action of a catalyst, and obtaining cyclohexanone-oxime and cyclohexanone at high yield, wherein the cyclohexanone circulates in the reaction process and is equivalent to a reaction medium; and efficient conversion of the N-cyclohexyl hexamethyleneimine into the cyclohexanone-oxime and the cyclohexanone is achieved through regulating the conversion conditions, such as the reaction temperature, the reaction pressure and the catalyst dosage. Multiple disadvantages of a traditional cyclohexanone-oxime preparation route are avoided, the reaction conditions are mild, the operation is simple, a product is high in yield, the utilization rate of resources is significantly improved and the preparation method is an environment-friendly synthesis method.
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Paragraph 0026; 0027
(2017/09/18)
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- A Solvent-Free Process for Synthesis of Imines by Iron-Catalyzed Oxidative Self- or Cross-Condensation of Primary Amines Using Molecular Oxygen as Sole Oxidant
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Abstract: The synthesis of imines by oxidative self- or cross-condensation of primary amines has been achieved using iron(II) bromide as the catalyst. The protocol is ligand-free, additive-free, solvent-free, and high-yielding and utilizes renewable oxygen as sole oxidant. The reaction tolerated a wide range of functionalities. Graphical Abstract: [Figure not available: see fulltext.]
- Gopalaiah, Kovuru,Saini, Anupama
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p. 1648 - 1654
(2016/08/30)
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- Heterogeneous Catalytic Reductive Amination of Carbonyl Compounds with Ni-Al Alloy in Water as Solvent and Hydrogen Source
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The heterogeneous catalytic reductive amination of carbonyl compounds has been achieved by reactions of ammonium hydroxide and various amines with ketones and aldehydes. The process is based on the application of Raney type Ni-Al alloy in an aqueous medium. The reaction of the carbonyl compounds with the amine provided the corresponding Schiff bases that immediately underwent a reduction to provide primary and secondary amines as products. The controlled reaction of the Al content of the alloy with the solvent water generates hydrogen, and the in situ formed Raney Ni serves as a hydrogenation catalyst. The method is a simple and efficient way of preparing a broad variety of primary and secondary amines.
- Sch?fer, Christian,Ni?anci, Bilal,Bere, Matthew P.,Da?tan, Arif,T?r?k, Béla
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p. 3127 - 3133
(2016/09/09)
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- Colloid and nanosized catalysts in organic synthesis: XIV. Reductive amination and amidation of carbonitriles catalyzed by nickel nanoparticles
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Hydrogenation of carbonitriles catalyzed by nickel nanoparticles in the presence of primary amines led to the predominant formation of unsymmetrical secondary amines. In the presence of secondary amines hydrogenation of nitrites provided enamines as main products. Hydrogenation of nitriles in the presence of formamide or acetamide afforded formyl or acetyl derivatives of primary amines.
- Popov, Yu. V.,Mokhov,Shcherbakova
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p. 798 - 805
(2016/06/13)
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- Mesoporous silica gel as an effective and eco-friendly catalyst for highly selective preparation of cyclohexanone oxime by vapor phase oxidation of cyclohexylamine with air
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A simple and environmentally benign approach to highly selective preparation of cyclohexanone oxime by vapor phase catalytic oxidation of cyclohexylamine with air over mesoporous silica gel under atmospheric pressure has been successfully developed in this work. The results demonstrate that the nonmetallic mesoporous silica gel is an effective and eco-friendly catalyst for the vapor phase selective oxidation of cyclohexylamine to cyclohexanone oxime and the surface silicon hydroxyl groups as active sites are responsible for the excellent catalytic performance of silica gel. The present silica gel catalyst has advantages of low cost, long-time stable reactivity, easy regeneration, and reusability. This method employing inexpensive mesoporous silica gel as catalyst and air as green terminal oxidant under facile conditions is a promising process and has the potential to enable sustainable production of cyclohexanone oxime from the selective oxidation of cyclohexylamine with air in industrial applications.
- Liu, Shuilin,You, Kuiyi,Jian, Jian,Zhao, Fangfang,Zhong, Wenzhou,Yin, Dulin,Liu, Pingle,Ai, Qiuhong,Luo, He'an
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p. 239 - 249
(2016/04/06)
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- Self-coupling of benzylamines over a highly active and selective supported copper catalyst to produce N-substituted amines by the borrowing hydrogen method
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Amines were used as hydrogen donor for the borrowing hydrogen methodology with a heterogeneous catalyst. Supported copper catalysts catalyzed the self-condensation reaction of primary amines to secondary amines/imines with high efficiency. The recyclable, non-leaching catalyst is synthesized by a sol-gel method, which allows entrapping copper nanoparticles in an alumina matrix. The synthesized copper catalysts were found to be active in the self-coupling of primary amines to produce secondary amines. The hydrogen donor for the transfer hydrogenation appears to be the primary amine, and no additional hydrogen or hydrogen transfer reagent is required. To the best of our knowledge, this is the first report of a copper based catalyst for this type of reaction using the borrowing hydrogen scheme.
- Liu, Huihui,Chuah, Gaik-Khuan,Jaenicke, Stephan
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p. 262 - 268
(2015/06/23)
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- Solid base catalyzed highly efficient N-alkylation of amines with alcohols in a solvent-free system
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Different from any other catalytic systems containing transition metals and additives, sodium hydroxide itself was found to be a unique and effective catalyst for the solvent-free synthesis of the secondary amines via the N-alkylation of amines with alcohols. For the reaction of aniline with benzyl alcohol, 99.6 mol% conversion of aniline and 99.5% selectivity of the product were achieved under optimal conditions. Also, high conversion and selectivity could be acquired for the N-alkylations of various amines with alcohols, implying the universality of this methodology. Mechanistic studies revealed that this novel reaction most possibly proceeds with a base-catalyzed mechanism.
- Lu,Sun,Wei,Peng,Zhou,Xia
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- Clean borrowing hydrogen methodology using hydrotalcite supported copper catalyst
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The catalytic activity of Mg-Al hydrotalcite supported copper catalyst was investigated for clean CC and CN bond forming reactions using alcohols as alkylating agent via borrowing hydrogen methodology. The catalyst showed excellent conversion of ketone and amine substrates (71-99%) to alkylated products with high selectivity in alkylation reactions.
- Dixit, Manish,Mishra, Manish,Joshi, Pradyuman A.,Shah, Dinesh O.
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- An investigation into cyclohexanone ammoximation over Ti-MWW in a continuous slurry reactor
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In the present study, the liquid-phase ammoximation of cyclohexanone with ammonia and hydrogen peroxide was studied using a MWW-type titanosilicate (Ti-MWW) catalyst in a continuous slurry reactor to develop a clean process for producing cyclohexanone oxime. The reaction parameters, which governed the cyclohexanone conversion, oxime selectivity and catalyst deactivation, were investigated by simulating the operating conditions of an industrial process. Under optimized reaction conditions, Ti-MWW produced a cyclohexanone conversion and oxime selectivity over 96% and 99%, respectively. Moreover, Ti-MWW was extremely robust and showed a longer lifetime than the conventional titanium silicalite-1 catalyst. The causes of deactivation were elucidated to be the coke deposition and partial dissolution of the zeolite framework of Ti-MWW during ammoximation. The deactivated Ti-MWW catalyst was regenerated effectively by a combination of acid treatment and cyclic amine-assisted structural rearrangement.
- Zhao, Song,Xie, Wei,Yang, Junxia,Liu, Yueming,Zhang, Yingtian,Xu, Biliang,Jiang, Jin-Gang,He, Mingyuan,Wu, Peng
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experimental part
p. 1 - 8
(2011/12/16)
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- Coordination and catalytic activity of ruthenium complexes containing tridentate P,N,O ligands
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The coordination chemistry of RuII ions with [2-(diphenylphosphanyl)-N-(o-hydroxybenzylidene)]aniline (PNO-H) and the methylated analogue PNO-Me have been studied. Thus, [(PNO)RuCl(dmso) 2] (1), [(PNO)2Ru] (2), [(PNO)RuCl(PPh3)] (3) and [(PNO)RuCl(CO)2] (4) were synthesized by reactions of various RuII precursors with PNO-H. Treatment of PNO-Me with [RuCl 2(dmso)4] resulted in in the formation of [P,N-(PNO-Me)Ru(dmso)2Cl2] (5). However, complexation of PNO-Me with [RuCl2(CO)3(THF)] (THF = tetrahydrofuran) provided a mixture of [P,N-(PNO-Me)Ru(CO)2Cl2] (6) and 4 because O-demethylation took place during the reaction. All of the Ru II complexes have been characterized by elemental analysis and spectroscopic techniques, as well as X-ray crystal structural analysis for 2, 4 and 6. The ruthenium complexes investigated in this work, except 2, are good precatalysts for the reductive amination of amine with alcohols, and 4 appears to be the best. Moreover, 4 can catalyze the direct amination of nitrobenzene with benzyl alcohol to the corresponding secondary amine. Ruthenium complexes containing P,N,O ligands have been synthesized and characterized. These Ru II species appear to be good catalysts for the reductive amination of amines or nitrobenzene with alcohols.
- Lee, Chun-Chin,Chu, Wan-Yi,Liu, Yi-Hong,Peng, Shie-Ming,Liu, Shiuh-Tzung
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experimental part
p. 4801 - 4806
(2011/12/05)
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- Selective hydrogenation of nitrocyclohexane to cyclohexanone oxime by alumina-supported gold cluster catalysts
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Metal oxides (Al2O3, SiO2, MgO)-supported Au cluster catalysts prepared by colloid deposition method and well established Au/TiO2 prepared by deposition-precipitation method were tested for the selective reduction of nitrocyclohexane into cyclohexanone oxime. The activity and selectivity depended strongly on the size of Au and support material. Au/Al2O3 with smaller Au particle size (2.5 nm) was the most effective catalyst, exhibiting a high cyclohexanone oxime yield (86%) under mild condition (0.6 MPa H2, 100 °C). To study the origin of support and size effects, in situ FTIR experiments for OH/D 2 exchange reaction and nitrobenzene adsorption combined with poisoning experiments using pyridine and acetic acid were carried out. It is suggested that cooperation of coordinatively unsaturated Au atoms and the acid-base pair site (Alδ+-Oδ- site) plays an important role in H2 dissociation step. Alδ+-O δ- site also acts as the adsorption site of the nitro group.
- Shimizu, Ken-Ichi,Yamamoto, Takumi,Tai, Yutaka,Satsuma, Atsushi
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experimental part
p. 54 - 59
(2011/10/02)
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- Nickel-catalyzed transfer semihydrogenation and hydroamination of aromatic alkynes using amines as hydrogen donors
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The transfer hydrogenation of diphenylacetylene to yield cis- and trans-stilbenes was achieved using a variety of amines as hydrogen donors and the complex 1 ([(dippe)Ni(μ-H)]2) in catalytic amounts (0.5% mol). The use of nucleophilic amines such as pyrrolidine in neat conditions afforded the hydroamination of diphenylacetylene, in moderate to high yields. Cyclization of 2-ethynylaniline also was carried out under similar conditions, with 1 in catalytic amounts, but in low yield, mainly due to the formation of homocoupling products of the starting material. The hydrogenation of diphenylacetylene by using other nitrogenated compounds such as aromatic N-heterocycles was addressed to give a metal-mediated process, using 1 in stoichiometric amounts.
- Reyes-Sanchez, Adan,Canavera-Buelvas, Farrah,Barrios-Francisco, Rigoberto,Cifuentes-Vaca, Olga L.,Flores-Alamo, Marcos,Garcia, Juventino J.
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experimental part
p. 3340 - 3345
(2011/08/22)
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- Polyethylene glycol clicked Co(ii) Schiff base and its catalytic activity for the oxidative dehydrogenation of secondary amines
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Copper catalyzed [3+2] cycloaddition "click method" provided an efficient and high yielding immobilization of cobalt(ii) Schiff base to the azido-functionalized MeOPEG5000; whereas the direct reaction between MeOPEG5000 and Co(ii) Schiff base did not produce any immobilization. The prepared catalyst was tested for the oxidative dehydrogenation of various secondary amines using TBHP as oxidant and could be easily recovered by precipitation with diethyl ether at the end of the reaction.
- Khatri, Praveen K.,Jain, Suman L.,Sivakumar K.,Sain, Bir
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experimental part
p. 3370 - 3374
(2011/06/25)
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- Liquid-phase hydroamination of cyclohexanone
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Activity and selectivity of supported Ni, Pt, and Pd catalysts were studied in the liquidphase reductive amination of cyclohexanone at temperatures ranging from 100 to 150 °C. The catalyst 20% Ni/SiO2 is most active and selective providing a maximum yield of cyclohexylamine. The influence of the reaction conditions on the parameters of the catalytic process was studied. A detailed analysis of the reaction products was carried out using 13C NMR spectroscopy and gas chromatography coupled with mass spectrometry (GC-MS). This made it possible to refine the reaction mechanism and to identify a new by-product earlier unknown in the literature.
- Ivanov,Dubkov,Babushkin,Pirutko,Semikolenov
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scheme or table
p. 1896 - 1901
(2011/07/08)
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- Direct amination of secondary alcohols using ammonia
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Hydrogen shuttle: For the first time secondary alcohols and ammonia can be directly converted into primary amines with a selectivity of up to 99% by using a simple ruthenium/phosphine catalyst (see scheme; R1, R2= alkyl, aryl, alkenyl; M=[Ru3(CO)12]; and L=phosphine ligand).
- Pingen, Dennis,Mueller, Christian,Vogt, Dieter
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supporting information; experimental part
p. 8130 - 8133
(2011/02/22)
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- Oxidation of amines over alumina based catalysts
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Amines were oxidized by molecular oxygen in the vapor phase at atmospheric pressure over alumina and silicotungstic acid/alumina catalysts. The study is focused on the influence of structure of amine and catalyst properties on the composition of the main reaction products and byproducts. Coating of γ-Al2O3 with silicotungstic acid or its semisalt can significantly enhance its catalytic activity in amine oxidation. The adsorption of amine on weak acidic sites of catalyst is essential for its oxidation to main reaction products. Cycloalkylamines are oxidized mainly to cyclic oximes (selectivity up to 64%) and Schiff bases of appropriate cycloalkanone and cycloalkylamine (selectivity up to 38%). Mainly nitriles (selectivity up to 55%) and appropriate Schiff bases (selectivity up to 54%) were observed in the oxidation products of primary alkylamines. Their molar ratio depends on the catalyst acidity and reaction conditions. 1,6-Hexanediamine is oxidized mainly to caprolactam (yield 48%) and other cyclic lactames and Schiff bases as well as to dinitrile (yield 13%).
- Rakottyay, Karol,Kaszonyi, Alexander,Vají?ek, Stanislav
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experimental part
p. 33 - 41
(2010/08/22)
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- Selective hydrogenation of nitrocyclohexane to cyclohexanone oxime with H2 on decorated Pt nanoparticles
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A Pt catalyst has been designed to convert nitrocyclohexane into cyclohexanone oxime under mild hydrogenation conditions (4 bar of H2, 383 K, and solvent-free media). It has been found that the partial reduction of the nitro group to the oxime
- Serna, Pedro,Lopez-Haro,Calvino,Corma, Avelino
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scheme or table
p. 328 - 334
(2009/07/10)
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- Environmentally friendly chemoselective oxidation of primary aliphatic amines by using a biomimetic eiectrocatalytic system
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Environmentally friendly oxidation of primary aliphatic amines to imines has been successfully achieved, under metal-free conditions, by the use of diverse electrogenerated o-azaqui-none mediators. High catalytic performance, together with high chemoselec
- Largeron, Martine,Chiaroni, Angele,Fleury, Maurice-Bernard
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p. 996 - 1003
(2008/09/21)
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- The reaction of nitrosodicyclohexylamine with organolithiums
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The detailed study of the reaction of N-nitrosamines with organolithium compounds, under different reaction conditions, allowed the development of a useful methodology for the synthesis of substituted hydrazones and trialkyl hydrazines. The reaction proved to be very sensitive to the reaction conditions, and different main products can be obtained by ine tuning of several variables. With the purpose of searching into the reaction mechanism, a careful isolation, characterization, and quantitative determination of several minor products was carried out. N,N-dicyclohexylamine, N-cyclohexylidencyclohexyl amine, and N,N,N′-dicydohexylalkylhydrazines, were the main side products identified after the work up of the reaction mixtures. With the same aim, the kinetics of the reaction of N-nitrosodicyclohexylamine with n-BuLi, was determined at temperatures in the range 0°C room temperature. Under the conditions leading to the trialkyl hydrazine, the results show an abrupt slowdown of the reaction rate, after a short reaction time. This result, together with other observations, such as the recovering of hydrazone even when using high [RLi], is indicative of equilibrium involving different species in the reaction mixture. The isolation of reduction products, as well as additional experiments carried out with lithium dialkylamides and NO, allowed suggestion of an overall mechanistic scheme for the complex consecutive and parallel reactions, that is consistent with the afforded evidences. Copyright
- Vazquez, Alvaro J.,Rodriguez, Cristian,Nudelman, N. Sbarbati
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experimental part
p. 1098 - 1104
(2009/10/26)
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- Synthesis, properties, and oxidizing ability of areno-annulated 1,3-dimethyl-10-phenylcyclohepta[4,5]pyrrolo[2,3-d]pyrimidine-2,4(1,3H) -dionylium ions
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Novel areno-annulated 1,3-dimethyl-10-phenylcyclohepta[4,5]pyrrolo[2,3-d] pyrimidine-2,4(1,3H)-dionylium ions 12a,b+·BF4 - and 16a+-BF4- were synthesized by three-step reactions, starting f
- Naya, Shin-Ichi,Ohtoshi, Hiroshi,Nitta, Makoto
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p. 176 - 184
(2007/10/03)
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- Novel photo-induced oxidative cyclization of 1,3-dimethyl-5-(1- arylmethylidene)pyrimidine-2,4,6(1,3,5H)-triones: Synthesis and properties of areno[5,6]pyrano[2,3-d]pyrimidine-2,4(1,3H)-dionylium ions and their photo-induced autorecycling oxidizing reacti
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Novel photo-induced oxidative cyclization was accomplished to synthesize areno[b]pyrimido[5,4-e]pyran-2,4(1,3H)-dionylium ions 13a-c+· ClO4-. Furthermore, 13a-c+·BF 4- and their phenyl-subs
- Naya, Shin-Ichi,Miyagawa, Masashi,Nitta, Makoto
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p. 4919 - 4930
(2007/10/03)
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- Novel synthesis, properties, and NAD+-NADH type redox ability of 1,3-dimethylcyclohepta[4,5]pyrrolo[2,3-d]pyrimidine-2,4(1,3H)-dionylium ions annulated with additional pyrrolo[2,3-d]pyrimidine-1,3(2,4H)-dione and furan analogue, and their hydride adducts
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A convenient preparation of novel cations 11a,b+·BF 4- and 12a,b+·BF4 -, which are derived from annulation of the 1,3-dimethylcyclohepta[4, 5]pyrrolo[2,3-d]pyrimidine-2,4(1,3H)-dionylium ion with additional pyrrolo[2,3-d]pyrimidine-1,3(2,4ii)-dione and a furan analogue, was accomplished by a novel oxidative cyclization of 1,7-dihydro-7-[1′,3′-dimethyl- 2′,4′(1′,3′H)-dioxo-6′-(phenylamino) -pyrimidin-5′-yl]-1,3-dimethyl-10-phenylcyclohepta[4,5]pyrrolo[2,3-d] pyrimidine-2,4(1,3H)-dione 9 and its furan-analogue by using DDQ or photoirradiation under aerobic conditions. Structural characteristics of 11a,b+ and 12a,b+ were clarified on inspection of the UV-vis and NMR spectral data as well as X-ray crystal analyses. The stability of cations 11a,b+ and 12a,b+ is expressed by the pK R+ values that were determined spectrophotometrically to be 10.7-12.6. The electrochemical reduction of 11a,b+·BF 4 and 12a,b+·BF4- exhibited reduction potential at -0.93 to -1.00 (V vs Ag/AgNO3). The first reduction potential of 11a+ was reversible due to steric hindrance of two phenyl groups. The photoinduced oxidation reaction of 11a,b +·BF4- and 12a,b+· BF4- toward some amines under aerobic conditions was carried out to give the corresponding imines (isolated by converting to the corresponding 2,4-dinitrophenylhydrazones) with the recycling numbers of 0.6-30.3. Furthermore, as an example of the NAD+-NADH models, the reduction of a pyruvate analogue and some carbonyl compounds with the hydride-adduct of 11a+-BF4- was accomplished for the first time to give the corresponding alcohol derivatives.
- Naya, Shin-Ichi,Nishimura, Junya,Nitta, Makoto
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p. 9780 - 9788
(2007/10/03)
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- Tetrahydro-indazole cannabinoid modulators
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This invention is directed to a tetrahydro-indazole cannabinoid modulator compound of formula I: and a method for use in treating, ameliorating or preventing a cannabinoid receptor mediated syndrome, disorder or disease.
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Page/Page column 120-122
(2008/06/13)
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- Synthesis of ene-allenes via palladium-catalyzed hydride-transfer reaction of propargylic amines under mild conditions
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The palladium-catalyzed allene transformation reaction from propargylic amines proceeded in the presence of Pd2(dba)3· CHCl3 (5 mol %) and (C6F5)2PC 2H4P(C6
- Nakamura, Hiroyuki,Tashiro, Satoshi,Kamakura, Takaya
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p. 8333 - 8336
(2007/10/03)
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- Process for preparation of cyclohexanone oxime
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A method for producing cyclohexanone oxime, which comprises the steps of (1) subjecting to an amination reaction a starting material selected from the group consisting of cyclohexanol, cyclohexanone and a mixture thereof, thereby obtaining cyclohexylamine, and (2) subjecting the obtained cyclohexylamine to a partial oxidation reaction, thereby obtaining cyclohexanone oxime, wherein a by-product (α) formed in the step (1) and/or a by-product (β) formed in the step (2) are/is recycled to a reaction system of the amination reaction in the step (1).
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- PROCESS FOR PRODUCING CYCLOHEXANONE OXIME
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A method for producing cyclohexanone oxime, comprising the steps of:(1) subjecting cyclohexene or cyclohexanol to amination to obtain cyclohexylamine, and(2) subjecting the obtained cyclohexylamine to partial oxidation to obtain cyclohexanone oxime.
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Page/Page column 16
(2008/06/13)
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- A synthetic approach to the stemona alkaloids
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This paper describes our work developing a strategy for the construction of the typical core structure of the Stemona alkaloids. The approach is to control the relative stereochemistry of the groups on the core 1-azabicyclo[5.3.0]decane ring system by a [3,3] sigmatropic rearrangement of an acylimmonium ion followed by selective reduction. After optimization, this reaction sequence afforded the desired diastereomer in 62% yield. Further efforts were directed toward elaboration of the characteristic butyrolactone substituent.
- Hinman,Heathcock
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p. 7751 - 7756
(2007/10/03)
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