- Facile Synthesis of Tuneable Azophosphonium Salts
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Azophosphonium salts have a facile synthesis and can be readily tuned at the para position of the aryl group and at the phosphorus position with the use of bulky phosphines, leading to a range of coloured compounds. A relation between the Hammett σ+para constant and the colour and 31P NMR chemical shift was explored. The compounds were characterised by NMR spectroscopy, UV/Vis spectroscopy and single-crystal X-ray structure crystallography.
- Habraken, Evi R. M.,van der Zee, Lars J. C.,van de Vrande, Koen N. A.,Jupp, Andrew R.,Nieger, Martin,Ehlers, Andreas W.,Slootweg, J. Chris
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Read Online
- Synthesis and DNA-binding ability of pyrrolo[2,1-c][1,4]benzodiazepine- azepane conjugates
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A series of pyrrolobenzodiazepine-azepane conjugates linked through different alkane spacers have been prepared and their DNA thermal denaturation studies have been carried out. One of the compound (4b), elevates the DNA helix melting temperature of the CT-DNA by 2.0°C after incubation for 36 h at 37°C.
- Kamal, Ahmed,Reddy, D. Rajasekhar,Reddy, P. S. Murali Mohan,Rajendar
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Read Online
- Aluminum Metal-Organic Framework-Ligated Single-Site Nickel(II)-Hydride for Heterogeneous Chemoselective Catalysis
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The development of chemoselective and heterogeneous earth-abundant metal catalysts is essential for environmentally friendly chemical synthesis. We report a highly efficient, chemoselective, and reusable single-site nickel(II) hydride catalyst based on robust and porous aluminum metal-organic frameworks (MOFs) (DUT-5) for hydrogenation of nitro and nitrile compounds to the corresponding amines and hydrogenolysis of aryl ethers under mild conditions. The nickel-hydride catalyst was prepared by the metalation of aluminum hydroxide secondary building units (SBUs) of DUT-5 having the formula of Al(μ2-OH)(bpdc) (bpdc = 4,4′-biphenyldicarboxylate) with NiBr2 followed by a reaction with NaEt3BH. DUT-5-NiH has a broad substrate scope with excellent functional group tolerance in the hydrogenation of aromatic and aliphatic nitro and nitrile compounds under 1 bar H2 and could be recycled and reused at least 10 times. By changing the reaction conditions of the hydrogenation of nitriles, symmetric or unsymmetric secondary amines were also afforded selectively. The experimental and computational studies suggested reversible nitrile coordination to nickel followed by 1,2-insertion of coordinated nitrile into the nickel-hydride bond occurring in the turnover-limiting step. In addition, DUT-5-NiH is also an active catalyst for chemoselective hydrogenolysis of carbon-oxygen bonds in aryl ethers to afford hydrocarbons under atmospheric hydrogen in the absence of any base, which is important for the generation of fuels from biomass. This work highlights the potential of MOF-based single-site earth-abundant metal catalysts for practical and eco-friendly production of chemical feedstocks and biofuels.
- Antil, Neha,Kumar, Ajay,Akhtar, Naved,Newar, Rajashree,Begum, Wahida,Dwivedi, Ashutosh,Manna, Kuntal
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p. 3943 - 3957
(2021/04/12)
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- Commercially Available CuO Catalyzed Hydrogenation of Nitroarenes Using Ammonia Borane as a Hydrogen Source
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Tandem ammonia borane dehydrogenation and nitroarenes hydrogenation has been reported as a novel strategy for the preparation of aromatic amines. However, the practical application of this strategy is subjected to the high-cost and tedious preparation of supported noble metal nanocatalysts. The commercially available CuO powder is herein demonstrated to be a robust catalyst for hydrogenation of nitroarenes using ammonia borane as a hydrogen source under mild conditions. Numerous amines (even sterically hindered, halogenated, and diamines) could be obtained through this method. This monometallic catalyst is characteristic of support-free, excellent chemoselectivity, low-cost, and high recyclability, which will favor its future utilization in preparative reduction chemistry. Mechanistic studies are also carried out to clarify that diazene and azoxybenzene are key intermediates of this heterogeneous reduction.
- Du, Jialei,Chen, Jie,Xia, Hehuan,Zhao, Yiwei,Wang, Fang,Liu, Hong,Zhou, Weijia,Wang, Bin
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p. 2426 - 2430
(2020/03/30)
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- Effect of linker and metal on photoreduction and cascade reactions of nitroaromatics by M-UiO-66 metal organic frameworks
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The use of metal organic frameworks (MOFs) as photocatalysts is a promising and growing area of research. Given the diverse architectures, linkers, and metals, it is important to understand their effects on catalysis. Herein we compare six MOFs of the UiO-66 family towards photocatalytic reduction of nitro-aromatics to anilines. These MOFs differ in metal identity (Hf, Zr) and linker, and hence this systematic study provides insights to developing next generation MOFs. We found that Hf-based MOFs are superior to the more commonly studied Zr-analogues. Moreover, the linker identity also impact the photocatalysis, with pyridine-based linkers out-performing aniline based linkers and those that lack an embedded basic site. The MOFs studied have unique selectivities for the photoreduction and also allow for the one-pot synthesis of imines from aromatic aldehydes and nitro-aromatics.
- Elkin,Saouma
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supporting information
(2019/08/30)
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- Hydrogenation of nitroarenes catalyzed by a dipalladium complex
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A dipalladium complex [Pd2(L)Cl2](PF6)2 (2), via the substitution of (PhCN)2PdCl2 with 5-phenyl-2,8-bis(6′-bipyridinyl)-1,9,10-anthyridine (L) followed by the anion exchange, was found to be a good pre-catalyst for the reduction of nitroarenes to yield the corresponding anilines under atmospheric pressure of hydrogen in methanol. This method provides a straightforward access to a diverse array of functionalized anilines, exhibiting a possible application in synthetic chemistry. The catalytic activity of this complex is enhanced by the di-metallic system via the synergistic effect.
- Hung, Ming-Uei,Yang, Shu-Ting,Ramanathan, Mani,Liu, Shiuh-Tzung
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- Rapid and convenient conversion of nitroarenes to anilines under microwave conditions using nonprecious metals in mildly acidic medium
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Nitroarenes are reduced to the corresponding aniline derivatives using iron or zinc under mild conditions under microwave heating conditions. Mild acidity is provided by ammonium chloride in an aqueous methanol medium. The conditions are tolerant to other functional groups, with the exception of bromoalkyl derivatives, which yield complex reaction mixtures; otherwise, yields are generally quite high (80–99%).
- Keenan, Corey S.,Murphree, S. Shaun
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supporting information
p. 1085 - 1089
(2017/05/25)
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- Continuous Production of Biorenewable, Polymer-Grade Lactone Monomers through Sn-Β-Catalyzed Baeyer–Villiger Oxidation with H2O2
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The Baeyer–Villiger oxidation is a key transformation for sustainable chemical synthesis, especially when H2O2 and solid materials are employed as oxidant and catalyst, respectively. 4-substituted cycloketones, which are readily available from renewables, present excellent platforms for Baeyer–Villiger upgrading. Such substrates exhibit substantially higher levels of activity and produce lactones at higher levels of lactone selectivity at all values of substrate conversion, relative to non-substituted cyclohexanone. For 4-isopropyl cyclohexanone, which is readily available from β-pinene, continuous upgrading was evaluated in a plug-flow reactor. Excellent selectivity (85 % at 65 % conversion), stability, and productivity were observed over 56 h, with over 1000 turnovers (mol product per mol Sn) being achieved with no loss of activity. A maximum space–time yield that was almost twice that for non-substituted cyclohexanone was also obtained for this substrate [1173 vs. 607 g(product) kg(catalyst)?1 cm?3 h?1]. The lactone produced is also shown to be of suitable quality for ring opening polymerization. In addition to demonstrating the viability of the Sn-β/H2O2 system to produce renewable lactone monomers suitable for polymer applications, the substituted alkyl cyclohexanones studied also help to elucidate steric, electronic, and thermodynamic elements of this transformation in greater detail than previously achieved.
- Yakabi, Keiko,Mathieux, Thibault,Milne, Kirstie,López-Vidal, Eva M.,Buchard, Antoine,Hammond, Ceri
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p. 3652 - 3659
(2017/09/13)
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- Synthesis of N-aryl and N-heteroaryl hydroxylamines via partial reduction of nitroarenes with soluble nanoparticle catalysts
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Polystyrene-supported ruthenium nanoparticles enable the selective hydrazine-mediated reduction of nitroarenes to hydroxylamine products in high yield and selectivity. Key to obtaining the hydroxylamine product in good yield was the use of organic solvents capable of solubilizing the polystyrene-supported nanoparticle catalyst. N-aryl and N-heteroaryl hydroxylamines are generated under exceptionally mild conditions and in the presence of a various easily reduced functional groups.
- Tyler, Jefferson H.,Nazari, S. Hadi,Patterson, Robert H.,Udumula, Venkatareddy,Smith, Stacey J.,Michaelis, David J.
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supporting information
p. 82 - 86
(2016/12/23)
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- Metal-Free One-Pot Synthesis of N,N′-Diarylamidines and N-Arylbenzimidazoles from Arenediazonium Salts, Nitriles, and Free Anilines
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A highly efficient and facile metal-free, one-pot reaction has been developed to afford diversely substituted N-arylbenzimidazoles through chemoselective in situ generation of N,N′-diarylamidines from arenediazonium salts, nitriles, and free anilines. The advantages of this protocol consist of the operationally easy and simple one-pot procedure under metal-free and mild conditions, the direct use of inexpensive and commercially available chemicals, and thus, a cost-effective and greener process.
- Youn, So Won,Lee, Eun Mi
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p. 5728 - 5731
(2016/11/17)
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- Well-structured bimetallic surface capable of molecular recognition for chemoselective nitroarene hydrogenation
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Unprecedented molecular recognition ability governed by a simple bimetallic surface is reported. A series of Rh-based ordered alloys supported on silica gel (RhxMy/SiO2, where M is Bi, Fe, Ga, Ge, In, Ni, Pb, Sb, Sn, or Zn) were tested in the hydrogenation of nitrostyrene to form aminostyrene. RhIn/SiO2 showed remarkably high catalytic activity and good selectivity under 1 atm H2 at room temperature. Moreover, various other nitroarenes containing carbonyl, cyano, or halo moieties were selectively hydrogenated into the corresponding amino derivatives using RhIn/SiO2. Kinetic study and density functional theory (DFT) calculations revealed that the high selectivity originates from RhIn/SiO2 adsorbing nitro groups much more favorably than vinyl groups. In addition, the DFT calculations indicated that the RhIn ordered alloy presents concave Rh rows and convex In rows on its surface, which are able to capture the nitro group with end-on geometry while effectively minimizing vinyl-π adsorption. Thus, the specific and highly ordered surface structure of RhIn enables the chemoselective molecular recognition of nitro groups over vinyl groups through geometric and chemical effects.
- Furukawa, Shinya,Takahashi, Katsuya,Komatsu, Takayuki
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p. 4476 - 4484
(2016/07/06)
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- Transfer hydrogenation of nitroarenes to arylamines catalysed by an oxygen-implanted MoS2 catalyst
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We present an efficient approach for chemoselective synthesis of various functionalized arylamines from nitroarenes over an oxygen-implanted MoS2 catalyst (O-MoS2). The HRTEM, XRD, XPS, Raman, EXAFS and NH3-TPD characterizations show the existence of MoIVOx structure and abundant coordinative unsaturated (CUS) Mo sites in the 2D-layer structure of O-MoS2. In the transfer hydrogenation of nitroarenes with hydrazine hydrate, the MoIVOx structure works as the catalytic active center. The N2H4 selectively decomposes to the active hydrogen species in polar electronic states (Hδ? and Hδ+), which show high chemoselectivity toward the nitro reduction over [Formula presented], [Formula presented], and [Formula presented] groups. The O-MoS2 catalyst can be recovered in a facile manner from the reaction mixture and recycled four times without any significant loss of activity.
- Zhang, Chaofeng,Zhang, Zhixin,Wang, Xu,Li, Mingrun,Lu, Jianmin,Si, Rui,Wang, Feng
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- Preparation method of arbidol hydrochloride
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The invention discloses a preparation method of arbidol hydrochloride. P-nitrophenol which is cheap and easy to obtain is innovatively adopted as the raw material, and through acetylation, nitroreduction, an indole ring reaction, a methylation reaction, bromination, a reaction with thiophenol and deprotection, a Mannich reaction and salification, arbidol hydrochloride is obtained. Reaction conditions of the whole synthesis process are mild, the raw material can be conveniently obtained, the character of the product is good, the yield is high, few by-products are generated, reaction selectivity and purity are high, environmental friendliness is achieved, production cost is low, and the method is suitable for industrial production; the defects that in the prior art, selectivity is low, many by-products are generated, the yield is low, precious catalysts are used, and serious environmental pollution is caused are overcome.
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Paragraph 0024; 0042; 0044
(2017/02/09)
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- Synthesis of unsaturated secondary amines by direct reductive amination of aliphatic aldehydes with nitroarenes over Au/Al2O3 catalyst in continuous flow mode
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A series of unsaturated secondary amines was successfully synthesized by direct reductive amination of aliphatic aldehydes with nitroarenes over a 2.5% Au/Al2O3 catalyst in a continuous flow reactor using molecular hydrogen as a reducing agent. In most cases, the targeted secondary amines were obtained in good to excellent yields. Interestingly, the hydrogenation of CC group is practically absent in both initial aldehydes and secondary amines under the reaction conditions. It was found that the introduction of electron-donating substituents in the para- and meta-position of nitrobenzenes increased the yield of secondary amine, while in the case of nitrobenzenes with electron-withdrawing substituents or electron-donating substituents in the ortho-position a decrease in the yield of the target product was observed.
- Nuzhdin,Artiukha,Bukhtiyarova,Zaytsev, S. Yu,Plyusnin,Shubin, Yu V.,Bukhtiyarov
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p. 88366 - 88372
(2016/09/28)
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- Identification of 3-hydroxy-4[3,4-dihydro-3-oxo-2H-1,4-benzoxazin-4-yl]-2,2-dimethyldihydro-2H-benzopyran derivatives as potassium channel activators and anti-inflammatory agents
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The present study described the design, synthesis and identification of 3-hydroxy-4[3,4-dihydro-3-oxo-2H-1,4-benzoxazin-4-yl]-2,2-dimethyldihydro-2H-benzopyran derivatives. Their biological activity was tested for KATP channel opener as antihypertensives, COX-1 and COX-2 activity. The results were compared with the activity of cromakalim, ibuprofen and celecoxib. The study aimed at exploring the influence of introduction of a benzoxazine substituent at position 6 of various derivatives of benzopyrans in order to improve biological activity. Several compounds were found to be equipotent or even more potent than cromakalim. Out of these nitro-substituted benzopyrans, nitro substitution at benzoxazino group possessed potent antihypertensive activity in the R/S isomers. With amino derivatives, activity remains constant when compared with standard cromakalim. Similarly, compounds 17b, 17c, 17e and 17h have exhibited around 40 % inhibition of COX-1 as compared to the inhibition of COX-2. Only two compounds 17g and 17i exhibited effective inhibition more than 50 % of COX-2 compared with the inhibition of COX-1 at a concentration of 0.3 mg/ml.
- Bano, Mohsina,Barot, Kuldipsinh P.,Jain, Shailesh V.,Ghate, Manjunath D.
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p. 3008 - 3020
(2015/03/18)
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- Water at elevated temperatures (WET): Reactant, catalyst, and solvent in the selective hydrolysis of protecting groups
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Water at elevated temperatures (WET) can act simultaneously as reactant, solvent, and catalyst in reaction processes. WET has been successfully employed in the removal of protecting groups alleviating the need for added strong acids/bases, subsequent neutralization and waste salt elimination. The protocols for the water-mediated removal of several common protecting groups such as tert-butyl carbamates (N-Boc) from 125 to 150 °C, acetamide (N-Ac) at 275 °C and acetate esters (O-Ac) at 250 °C are reported for different model aryl compounds. In addition, high yields and selective deprotection of one protecting group in the presence of another by simply tuning the temperature is demonstrated. In order to gain further insights into reaction processes, the aqueous solubilities of several of the reactants, the kinetics and mechanisms associated with some of these reactions are also discussed. the Partner Organisations 2014.
- Medina-Ramos, Wilmarie,Mojica, Mike A.,Cope, Elizabeth D.,Hart, Ryan J.,Pollet, Pamela,Eckert, Charles A.,Liotta, Charles L.
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p. 2147 - 2155
(2014/04/17)
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- A magnetically separable gold catalyst for chemoselective reduction of nitro compounds
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Magnetically separable gold-nanoparticle catalyst was prepared, and it showed excellent activity for chemoselective reduction of nitroarenes with hydrosilanes. The Royal Society of Chemistry 2013.
- Park, Sungho,Lee, In Su,Park, Jaiwook
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supporting information
p. 395 - 399
(2013/02/23)
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- Pinacol as a new green reducing agent: Molybdenum-catalyzed chemoselective reduction of sulfoxides and nitroaromatics
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Pinacol is disclosed as a new chemoselective and environmentally benign reducing agent for sulfoxides and nitroaromatics assisted by readily available dichlorodioxomolybdenum(VI) complexes as catalysts. A wide range of substrates including those bearing challenging functional groups has been efficiently and selectively reduced with acetone and water being the only by-products of these reactions. Copyright
- Garcia, Nuria,Garcia-Garcia, Patricia,Fernandez-Rodriguez, Manuel A.,Rubio, Ruben,Pedrosa, Maria R.,Arnaiz, Francisco J.,Sanz, Roberto
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supporting information; experimental part
p. 321 - 327
(2012/04/11)
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- Characterization of novel Cs and K substituted phosphotungstic acid modified MCM-41 catalyst and its catalytic activity towards acetylation of aromatic alcohols
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TheMCM-41 supported Cs2.5H0.5PW12O 40 and K2.5H0.5PW12O40 salts were synthesized by incipient wetness impregnation method. The solids were characterized by N2 adsorption-desorption isotherms, FTIR, XRD, and temperature programmed desorption, etc. This catalyst has been found to exhibit excellent activity for acetylation of phenolic compounds. The catalyst is stable and reusable giving 96% conversion with 100% selectivity towards acetate products. Indian Academy of Sciences.
- Rana, Surjyakanta,Mallick, Sujata,Rath, Dharitri,Parida
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p. 1117 - 1125
(2013/03/13)
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- An improved synthesis of a b-blocker celiprolol hydrochloride
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Celiprolol hydrochloride, a β-blocker drug, has been synthesised from 4-chloronitrobenzene. The route involved hydrolysis of the chloride and acetylation of the phenol, reduction of the nitro group, and acylation of theamine. This was followed by Fries rearrangement of the acetyl group, Williamson etherification with epichlorohydrin, followed by opening of the epoxide ring and salt formation. The overall yield of celipropol was 39.1% on the basis of 4-chloronitrobenzene. The Fries rearrangement was substantially improved. The process is suitable for industrial application because of its convenient and environmentally friendly reaction conditions.
- Ji, Li,Qian, Chao,Chen, Xin-Zhi,Mao, Xiao-Yuan
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p. 640 - 643,4
(2020/07/30)
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- Selective reduction of nitro compounds using CeY zeolite under microwaves
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Aliphatic and aromatic nitro compounds were selectively reduced to their corresponding amino derivatives in good yields using formic acid and CeY zeolite under monomode reactor. This system is found to be compatible with several sensitive functionalities. Beside the recycling result showed it had a long catalyst lifetime and could maintain activity even after being used for 20 cycles.
- Arya, Kapil,Dandia, Anshu
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experimental part
p. 55 - 58
(2010/09/05)
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- The use of immobilized crown ethers as in-situ N-protecting groups in organic synthesis and their application under continuous flow
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In addition to their high affinity for inorganic cations, crown ethers have been shown to efficiently sequester ammonium ions, forming a stable adduct via hydrogen bonding. Using this principle, several authors have reported the use of crown ethers as protecting groups for amines however to date, their widespread use has been somewhat precluded by the difficulties associated with removal of the crown ether from the resulting reaction mixture. In order to address this problem, we report the preparation of an immobilized 18-crown-6 ether derivative and its incorporation into a flow reactor, demonstrating the ability to use and recycle the reagent for the chemoselective O-acylation and alkylation of bifunctional compounds such as 4-(2-aminoethyl)phenol and 4-nitrophenol.
- Wild, Gareth. P.,Wiles, Charlotte,Watts, Paul,Haswell, Stephen J.
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experimental part
p. 1618 - 1629
(2009/05/26)
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- Boiling water-catalyzed neutral and selective N-Boc deprotection
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A general protocol for removing Boc groups from various types of nitrogen is reported and a preliminary investigation of the reaction mechanism indicates that water acts as a dual acid/base catalyst at elevated temperature. The Royal Society of Chemistry 2009.
- Wang, Jia,Liang, Yan-Liang,Qu, Jin
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supporting information; experimental part
p. 5144 - 5146
(2009/12/08)
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- Palladium-catalyzed silane/siloxane reductions in the one-pot conversion of nitro compounds into their amines, hydroxylamines, amides, sulfonamides, and carbamates
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A combination of palladium(II) acetate, aqueous potassium fluoride, and polymethylhydrosiloxane (PMHS) facilitates the room-temperature reduction of aromatic nitro compounds to anilines. These reactions tend to be quick (30 min), high-yielding, and tolerate a range of other functional groups. Replacement of PMHS/KF with triethylsilane allows for the reduction of aliphatic nitro compounds to their corresponding hydroxylamines. Depending on the substrate, both conditions can allow for the in situ conversion of the product amines into amides, sulfonamides, and carbamates. Georg Thieme Verlag Stuttgart.
- Rahaim Jr., Ronald J.,Maleczka Jr., Robert E.
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p. 3316 - 3340
(2008/09/17)
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- Enzymatic Baeyer-Villiger oxidation of benzaldehydes
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The selectivity of the chemical Baeyer-Villiger oxidation of benzaldehydes depends on steric and electronic factors, the type of oxidizing agent and the reaction conditions. Here we report on the enzymatic Baeyer-Villiger oxidation of fluorobenzaldehydes
- Moonen, Marielle J. H.,Westphal, Adrie H.,Rietjens, Ivonne M. C. M.,Van Berkel, Willem J. H.
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p. 1027 - 1034
(2007/10/03)
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- Pd-catalyzed silicon hydride reductions of aromatic and aliphatic nitro groups
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(Chemical Equation Presented) Room-temperature reduction of aromatic nitro groups to amines can be accomplished in high yield, with wide functional group tolerance and short reaction times (30 min) using a combination of palladium(II) acetate, aqueous potassium fluoride, and polymethylhydrosiloxane (PMHS). Replacing PMHS/KF with triethylsilane allows aliphatic nitro groups to be reduced to their hydroxylamines.
- Rahaim Jr., Ronald J.,Maleczka Jr., Robert E.
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p. 5087 - 5090
(2007/10/03)
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- Reduction of nitro-aryl compounds with zinc in the presence of poly[N-(2-aminoethyl)acrylamido]-trimethylammonium chloride as a phase-transfer catalyst
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The new polymeric phase-transfer catalyst, poly[N-(2-aminoethyl)acrylamido] trimethylammonium chloride resin, catalyzes the reduction of nitroarenes to the corresponding aromatic amines with zinc powder in water and in high yields under mild conditions. Copyright Taylor & Francis, Inc.
- Mahdavi, Hossen,Tamami, Bahman
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p. 1121 - 1127
(2007/10/03)
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- Heteroaryl alkyl piperazine derivatives
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Novel compounds of the general formula: and pharmaceutically acceptable acid addition salts thereof, wherein the compounds are useful in therapy to protect skeletal muscles against damage resulting from trauma or to protect skeletal muscles subsequent to muscle or systemic diseases such as intermittent claudication, to treat shock conditions, to preserve donor tissue and organs used in transplants, in the treatment of diabetes, in the treatment of cardiovascular diseases including atrial and ventricular arrhythmias, Prinzmetal's (variant) angina, stable angina, and exercise induced angina, congestive heart disease, and myocardial infarction.
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- The hydrogenolysis of N-benzyl groups with a magnesium and ammonium formate
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The selective deprotection of several N-Bn amino derivatives to the corresponding amines and the removal of S-Bn and O-Bn groups from the protected amino acids with ammonium formate and magnesium is reported.
- Babu, S.N. Narendra,Srinivasa,Santhosh,Gowda, D. Channe
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- Hydrazinium monoformate mediated facile preparation of amines from azides catalyzed by zinc
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A variety of functionalized alkyl and aryl primary amines have been prepared from corresponding azides by reaction with hydrazinium monoformate in the presence of low cost commercial zinc dust at room temperature. Many other reducible substituents such as halogen, methoxy, phenol, acid. ethene and nitrile remain unaffected. The hydrogenation is fast, mild, clean, cost-effective and high yielding.
- Prasad,Srinivasa,Abiraj,Gowda, D. Channe
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p. 1787 - 1789
(2007/10/03)
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- Selective Removal of N-Boc Protecting Group from Aromatic Amines Using Silica Gel-Supported Sodium Hydrogen Sulfate and HY-Zeolite as Heterogeneous Catalysts
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Silica gel-supported sodium hydrogen sulfate and HY-zeolite were found to be efficient catalysts for the selective removal of the N-Boc protecting group from aromatic amines keeping intact the aliphatic N-Boc amines. HY-zeolite was used as a reusable catalyst.
- Ravindranath,Ramesh,Reddy, M. Ravinder,Das, Biswanath
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p. 1207 - 1208
(2007/10/03)
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- Hydrazinium monoformate: A new hydrogen donor. Selective reduction of nitrocompounds catalyzed by commercial zinc dust
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The nitro group in aliphatic and aromatic nitro compounds also containing reducible substituents such as ethene, nitrile, acid, phenol, halogen, ester, etc., are selectively and rapidly reduced at room temperature to corresponding amines in good yields by employing hydrazinium monoformate, in the presence of commercial zinc dust. It was observed that, hydrazinium monoformate is more effective than hydrazine or formic acid and reduction of nitro group occurs without hydrogenolysis in the low cost zinc dust compared to expensive metals like palladium.
- Gowda, Shankare,Gowda, B. K. Kempe,Gowda, D. Channe
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p. 281 - 289
(2007/10/03)
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- Zinc/hydrazine: A low cost-facile system for the reduction of nitro compounds
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The nitro group in aliphatic and aromatic nitro compounds also containing reducible substituents such as ethene, nitrile, carboxylic acid, phenol, halogen, ester etc., are selectively and rapidly reduced at room temperature to corresponding amines in good yields by employing 99-100% hydrazine hydrate, in the presence of commercial zinc dust. It was observed that, this system is equally compatible with existing methods, which employ expensive catalysts like palladium, platinum, ruthenium etc.
- Gowda, Shankare,Gowda, D. Channe
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p. 180 - 183
(2007/10/03)
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- Manganese mediated aqueous reduction of aromatic nitro compounds to amines
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A chemoselective reduction of aromatic nitro compounds to amines using Mn/CuCl2(cat.)/THF-H2O is described.
- Sarmah, Parijat,Dutta, Dilip K.
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p. 236 - 237
(2007/10/03)
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- Structure-activity relationship on human serum paraoxonase (PON1) using substrate analogues and inhibitors
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Substrate analogues based on the parent compounds paraoxon and phenyl acetate were tested on human serum paraoxonase (PON1) to explore the active site of the enzyme. Replacement of the nitro group of paraoxon with an amine or hydrogen, as well as electronic changes to the parent compound, converted these analogues into inhibitors. Introduction of either electron-withdrawing or donating groups onto phenyl acetate resulted in reduction in their rate of hydrolysis by PON1.
- Bargota, Rakesh S.,Akhtar, Mahmoud,Biggadike, Keith,Gani, David,Allemann, Rudolf K.
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p. 1623 - 1626
(2007/10/03)
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- Magnesium/ammonium formate promoted rapid, low-cost and selective reduction of nitro compounds
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The reduction of nitro compounds, both aliphatic and aromatic into corresponding amines has been achieved at room temperature in good yields by employing ammonium formate in the presence of low cost magnesium powder. The hydrogenation is fast and selective in the presence of other sensitive functionalities such as halogens, -OH, -OCH3, -CN, -COOR, -COOH etc. It was observed that, this system is equally compatible with existing methods, which employ expensive catalysts like palladium, platinum, ruthenium etc.
- Srinivasa,Abiraj,Gowda, D. Channe
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p. 2882 - 2884
(2007/10/03)
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- Hydrazine/magnesium mediated cost-effective and selective reduction of nitro compounds
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Hydrazine aided catalytic transfer hydrogenation has been employed for the reduction of both aliphatic and aromatic nitro compounds to corresponding amines. The use of low-cost magnesium, as catalyst leads to high yields of amino compounds under ambient conditions of temperature and pressure. Many commonly encountered functional groups like ethene, nitrile, acid, phenol, halogen etc. are compatible with the present system.
- Srinivasa,Abiraj,Gowda, D. Channe
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p. 2885 - 2887
(2007/10/03)
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- Heteroaryl alkyl piperazine derivatives
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Novel compounds of the general formula: and pharmaceutically acceptable acid addition salts thereof, wherein the compounds are useful in therapy to protect skeletal muscles against damage resulting from trauma or to protect skeletal muscles subsequent to muscle or systemic diseases such as intermittent claudication, to treat shock conditions, to preserve donor tissue and organs used in transplants, in the treatment of diabetes, in the treatment of cardiovascular diseases including atrial and ventricular arrhythmias, Prinzmetal's (variant) angina, stable angina, and exercise induced angina, congestive heart disease, and myocardial infarction.
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- Heteroaryl alkyl piperazine derivatives
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Novel compounds of the general formula: and pharmaceutically acceptable acid addition salts thereof, wherein the compounds are useful in therapy to protect skeletal muscles against damage resulting from trauma or to protect skeletal muscles subsequent to muscle or systemic diseases such as intermittent claudication, to treat shock conditions, to preserve donor tissue and organs used in transplants, in the treatment of cardiovascular diseases including atrial and ventricular arrhythmias, Prinzmetal's (variant) angina, stable angina, and exercise induced angina, congestive heart disease, and myocardial infarction.
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- Design, synthesis, and biological evaluation of aryloxyethyl thiocyanate derivatives against Trypanosoma cruzi
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As a continuation of our project aimed at the search for new and safe chemotherapeutic and chemoprophylactic agents against American trypanosomiasis (Chagas' disease), several drugs structurally related to 4-phenoxyphenoxyethyl thiocyanate (4) were designed, synthesized, and evaluated as antiproliferative agents against the parasite responsible for this disease, the hemoflagellated protozoan Trypanosoma cruzi. This thiocyanate derivative was previously shown to be an effective and potent agent against T. cruzi proliferation. Several drugs possessing thiocyanate groups proved to be effective growth inhibitors of T. cruzi growth. Among the designed compounds, it is important to point out the extremely potent activity shown by 11, 23, 38, 53, 90, 99, and 117 against the epimastigote forms of the parasite. All of them exhibited IC50 values in the low micromolar range, and these values were comparable with those presented by our lead drug 4 and ketokonazole, a well-known antiparasitic agent. The activity displayed by the nitrogen-containing derivative 90 was very promising with IC50 values of 3.3 μM. Several other thiocyanate derivatives also proved to be very potent inhibitors of the multiplication of T. cruzi epimastigotes, such as compounds 28, 33, 43, 48, 56, 61, 66, 71, 76, and 124. Compound 43 resulted in being a promising drug because it was also very effective against amastigotes, the clinically more relevant form of the parasite. This compound was 3-fold more potent than 4, while 11 showed nearly the same activity as our lead drug against intracellular T. cruzi. It was very surprising that the experimental juvenoid 124, although fairly devoid of activity against epimastigotes, was very effective against intracellular amastigotes growing in myoblasts. The rest of the designed compounds showed a broad degree of inhibitory action, from moderately active drugs to drugs almost devoid of antiparasitic activity. Compound 43 is an interesting example of an effective antichagasic agent that presents excellent prospectives not only as a lead drug but also to be used for further in vivo studies.
- Elhalem, Eleonora,Bailey, Brian N.,Docampo, Roberto,Ujváry, István,Szajnman, Sergio H.,Rodriguez, Juan B.
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p. 3984 - 3999
(2007/10/03)
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- Application of hydrazinium monoformate as new hydrogen donor with Raney nickel: A facile reduction of nitro and nitrile moieties
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The nitro groups in aliphatic and aromatic nitrocompounds also containing reducible substituents such as ethene, acid, phenol, halogen, ester etc., are rapidly reduced at room temperature to corresponding amines by employing hydrazinium monoformate, a new hydrogen donor, in the presence of Raney nickel. It was observed that the nitrile function also undergoes reduction to methylamine (-CH2-NH2). Hydrazinium monoformate is a more effective donor than hydrazine or formic acid and reduction of nitro and nitrile groups occurs without hydrogenolysis in the presence of low cost Raney nickel, compared to expensive metals like palladium, platinum or ruthenium. The reduction is reasonably fast, clean and high yielding.
- Gowda, Shankare,Gowda, D.Channe
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p. 2211 - 2213
(2007/10/03)
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- Zinc-catalyzed ammonium formate reductions: Rapid and selective reduction of aliphatic and aromatic nitro compounds
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Aliphatic and aromatic nitro compounds are selectively and rapidly reduced to their corresponding amino derivatives in good yields using ammonium formate and commercial zinc dust. This system is found to be compatible with several sensitive functionalities such as halogens, -OH, -OCH3, -CHO, -COCH3, -COC6H5, -COOH, COOC2H5, -CONH2, -CN, -CH=CH-COOH, -NHCOCH3. The reduction can be carried out not only with HCOONH4 but also with HCOOH.
- Gowda, D. Channe,Mahesh, B.,Gowda, Shankare
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- 5-(Tryptophyl)amino-1,3-dioxoperhydropyrido[1,2-c]pyrimidine-based potent and selective CCK1 receptor antagonists: Structure-activity relationship studies on the substituent at N2-position
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To establish structure-activity relationships a new series of analogues of the highly potent and selective CCK1 receptor antagonist (4aS,5R)-2-benzyl-5-(N-Boc-tryptophyl)amino-1,3-dioxoperhydropyrido [1,2-c]-pyrimidine (1a) modified at N2-position of the central scaffold has been prepared and evaluated as CCK receptor ligands. With this aim the N2-benzyl group has been replaced by methyl, cyclohexyl, aromatic groups, 1-phenylethyl, and 1-carboxy-2-phenylethyl group. Then, substituents with different electronic and steric properties were introduced into different positions of the phenyl group of analogues 19a and 19b. The results of the CCK receptor binding and in vitro functional activity evaluation suggest the importance of the lipophilic character and an appropriate spatial orientation of the moiety linked at the N2-position of the 1,3-dioxoperhydropyrido[1,2-c]pyrimidine template for potent and selective binding and antagonist activity at CCK1 receptor subtype. The 2-cyclohexyl and (2S)-1-naphthyl derivatives 18a and (2S)-20a have emerged as more potent and selective CCK1 receptor antagonists than the lead compound 1a. Additionally, the results confirm the (4aS,5R)-stereochemistry at the central bicyclic skeleton as an essential structural requirement for potent binding to this receptor subtype.
- Bartolomé-Nebreda,Pati?o-Molina,Martín-Martínez,Gómez-Monterrey,García-López,González-Mu?iz,Cenarruzabeitia,Latorre,Del Río,Herranz
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p. 2219 - 2228
(2007/10/03)
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- Nickel-catalyzed formic acid reductions. A selective method for the reduction of nitro compounds
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Aliphatic and aromatic nitro compounds were selectively reduced to their corresponding amino derivatives in good yields using formic acid and raney nickel. This system is found to be compatible with several sensitive functionalities such as halogens, -OH, -OCH3, -CHO, -COCH3-COC6H5, -COOH, -COOC2H5, -CONH2, -CN, -CH=CH-COOH, -NHCOCH3. The reduction can be carrid out not only with HCOOH but also with HCOONH4.
- Channe Gowda,Prakasha Gowda,Ramesha Baba,Gowda, Shankare
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p. 2889 - 2895
(2007/10/03)
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- Catalytic transfer hydrogenation of aromatic nitro compounds by employing ammonium formate and 5% platinum on carbon
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Aromatic nitro compounds were reduced to respective amines in high yields by using 5% platinum on carbon with ammonium formate or formic acid as hydrogen donor. It was observed that the former was mote efficient donor than the later. Further we have found that reduction of nitro groups occurs without hydrogenolysis of halogens and the reducible substituents which remains unchanged under the reaction conditions.
- Gowda,Mahesh
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p. 3639 - 3644
(2007/10/03)
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- Formic acid with 10% palladium on carbon: A reagent for selective reduction of aromatic nitro compounds
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The nitro group in aromatic nitro compounds also containing reducible substituents such as carbonyl, ethene, ethyne, nitrile, acid, phenol etc, is selectively and rapidly reduced at room temperature to corresponding amino derivatives in good yield employing formic acid in the presence of 10% palladium on carbon. The catalyst could be recovered and reused after washing with water and ethanol, and the results obtained indicate further, there is no apparent loss of catalytic activity.
- Channe Gowda,Gowda
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p. 709 - 711
(2007/10/03)
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- A facile procedure for reduction of azides to amines with aluminium triiodide
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It has been demonstrated that a wide variety of aromatic and aliphatic azides can be efficiently reduced to the corresponding amines in good yields with freshly prepared aluminium triiodide. Other functional groups such as ether, ester, nitro and halides remain uneffected.
- Barua, Apurba,Bez, Ghanashyam,Barua, Nabin C.
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p. 128 - 129
(2007/10/03)
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- A convenient and mild synthetic route to aminoarenes by reduction of nitroarenes with activated nickel and hydrazine hydrate
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Aminoarenes were obtained in excellent yields by reduction of corresponding nitroarenes with activated nickel powder and hydrazine hydrate. The nickel catalyst was prepared by the reduction of anhydrous nickelous chloride with Ultrasonically Dispersed Potassium.
- Li, Hongbin,Zhang, Rong,Wang, Hui,Pan, Yi,Shi, Yaozeng
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p. 3047 - 3052
(2007/10/03)
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- A New Acylation Catalyst
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Cobalt(II) chloride catalyses the acylation of alcohols and amines with anhydrides in excellent yields.
- Ahmad, Saeed,Iqbal, Javed
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p. 114 - 115
(2007/10/02)
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- Selective reduction of aromatic nitro compounds with stannous chloride in non acidic and non aqueous medium
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Aromatic nitro compounds are readily reduced by SnCl2, 2 H2O in alcohol or ethyl acetate or by anhydrous SnCl2 in alcohol where other reducible or acid sensitive groups such as aldehyde, ketone, ester, cyano, halogen and O-benzyl remain unaffected.
- Bellamy,Ou
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p. 839 - 842
(2007/10/02)
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