- Reductive C?N Coupling of Nitroarenes: Heterogenization of MoO3 Catalyst by Confinement in Silica
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The construction of C?N bonds with nitroaromatics and boronic acids using highly efficient and recyclable catalysts remains a challenge. In this study, nanoporous MoO3 confined in silica serves as an efficient heterogeneous catalyst for C?N cross-coupling of nitroaromatics with aryl or alkyl boronic acids to deliver N-arylamines and with desirable multiple reusability. Experimental results suggest that silica not only heterogenizes the Mo species in the confined mesoporous microenvironment but also significantly reduces the reaction induction period and regulates the chemical efficiency of the targeted product. The well-shaped MoO3@m?SiO2 catalyst exhibits improved catalytic performance both in yield and turnover number, in contrast with homogeneous Mo catalysts, commercial Pd/C, or MoO3 nanoparticles. This approach offers a new avenue for the heterogeneous catalytic synthesis of valuable bioactive molecules.
- Yang, Fu,Dong, Xuexue,Shen, Yang,Liu, Mengting,Zhou, Hu,Wang, Xuyu,Li, Lulu,Yuan, Aihua,Song, Heng
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p. 3413 - 3421
(2021/07/31)
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- ACETAMIDO DERIVATIVES AS DNA POLYMERASE THETA INHIBITORS
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Disclosed herein are certain acetamido derivatives that are DNA Polymerase Theta (Polθ) inhibitors of Formula (I). Also, disclosed are pharmaceutical compositions comprising such compounds and methods of treating diseases treatable by inhibition of Polθ such as cancer, including homologous recombination (HR) deficient cancers.
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Paragraph 0176
(2020/08/22)
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- Bifunctional Pincer Catalysts for Chemoselective Transfer Hydrogenation and Related Reactions
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A comparative study on the chemoselective transfer hydrogenation of nitroarenes to anilines and related processes using FA as the hydrogen source is described; these processes are catalyzed by a series of pincer catalysts equipped with different functional groups in the secondary coordination sphere. Some new (4 and 5) as well as previously reported (1–3) catalysts belonging to the family of bifunctional PC(sp3)P pincer complexes were employed in this study The reported compounds exhibited remarkably different catalytic activity behavior, depending on the nature of the functional groups. Transfer hydrogenation of nitrobenzene with FA as a hydrogen source was probed using iridium complexes 3 or 4 as a catalyst. Under the same conditions, the analogous palladium complex was found to be useful for the selective amidation of aniline with light carboxylic acids.
- Cohen, Shirel,Bilyachenko, Alexey N.,Gelman, Dmitri
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p. 3203 - 3209
(2019/02/09)
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- Hofmann N-alkylation of aniline derivatives with alcohols using ferric perchlorate immobilized on SiO2 as a catalyst through Box–Behnken experimental design
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An efficient method for the N-alkylation of poorly nucleophilic amines using ferric perchlorate immobilized on SiO2 as a catalyst is described. Fe(ClO4)3 was prepared from mixing iron(III) hydroxide and perchloric acid and adsorbed on silica gel. The catalyst was characterized using various techniques. The supported ferric perchlorate (Fe(ClO4)3/SiO2) revealed high efficiency and selectivity for N-alkylation of aromatic amines with alcohols to provide alkylated amines. Various secondary amines were synthesized from primary amines and alcohols in good to excellent yields, with water as the only by-product. The optimization of the reaction conditions was investigated using the response surface method, and involving the Box–Behnken design matrix. The conditions for optimal reaction yield and time were: amount of catalyst?=?0.34?mmol, temperature?=?60°C and molar ratio of amine to alcohol?=?1.2. The catalyst was recovered and reused for five cycles without a considerable decrease in catalytic activity. The stability of the recycled catalyst was investigated. The proposed method has numerous advantages including procedure simplicity, short reaction times, low cost, good to excellent yields, reusability of the catalyst and mild and environmentally benign conditions.
- Ghanimati, Mahdi,Abdoli Senejani, Masumeh,Isfahani, Tahereh Momeni,Bodaghifard, Mohammad Ali
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- Nickel(II) complex covalently anchored on core shell structured SiO2@Fe3O4 nanoparticles: A robust and magnetically retrievable catalyst for direct one-pot reductive amination of ketones
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A robust and efficient core shell structured magnetically retrievable nickel nanocatalytic system was fabricated via the covalent immobilization of 2-acetyl furan on the surface of an amine functionalized silica coated magnetic nanosupport followed by its metallation with nickel acetate. The newly synthesized magnetic silica based organic-inorganic hybrid nanocatalyst (Ni-ACF@Am-SiO2@Fe3O4) was systematically affirmed using several physico-chemical characterization tools such as FT-IR, XRD, VSM, SEM, TEM, EDS, ED-XRF and AAS. Thereafter, the catalytic performance of this Ni-ACF@Am-SiO2@Fe3O4 nanocatalyst was investigated in the one-pot reductive amination of ketones using NaBH4 as the reductant under neat conditions. The developed core shell magnetic silica based nickel nanocatalyst successfully afforded a structurally diverse range of secondary amines with high turnover frequency (TOF) and excellent conversion percentage. Additionally, it was found that this catalyst could not only be retrieved from the reaction vessel within a fraction of seconds using an external magnet but also be recycled for multiple runs without any discernible loss in its activity that rendered this protocol superior to all the previously established methodologies for the one-pot synthesis of substituted amines. Besides, some of the other fascinating features of this methodology that made it a potential candidate for addressing various economic and environmental concerns were ambient reaction conditions, broad substrate scope, simple workup procedure, shorter reaction time and cost effectiveness.
- Sharma, Rakesh Kumar,Dutta, Sriparna,Sharma, Shivani
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p. 2089 - 2101
(2016/03/19)
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- Alkylation of Amines with Alcohols and Amines by a Single Catalyst under Mild Conditions
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An efficient catalytic system for the alkylation of amines with either alcohols or amines under mild conditions has been developed, using cyclometallated iridium complexes as catalysts. The method has broad substrate scope, allowing for the synthesis of a diverse range of secondary and tertiary amines with good to excellent yields. By controlling the ratio of substrates, both mono- and bis-alkylated amines can be obtained with high selectivity. In particular, methanol can be used as the alkylating reagent, affording N-methylated products selectively. A strong solvent effect is observed for the reaction.
- Zou, Qingzhu,Wang, Chao,Smith, Jen,Xue, Dong,Xiao, Jianliang
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supporting information
p. 9656 - 9661
(2015/06/30)
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- Chemoselective hydrogenation of functionalized nitroarenes and imines by using carbon nanofiber-supported iridium nanoparticles
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The reaction of three types of carbon nanofibers (CNFs; platelet: CNF-P, tubular: CNF-T, herringbone: CNF-H) with Ir4(CO)12 in mesitylene at 165 °C provided the corresponding CNF-supported iridium nanoparticles, Ir/CNFs (Ir content=2.3-2.6 wt. %). Transmission electron microscopy (TEM) studies of these Ir/CNF samples revealed that size-controlled Ir nanoparticles (average particle size of 1.1-1.5 nm) existed on the CNFs. Among the three Ir/CNF samples, Ir/CNF-T showed an excellent catalytic activity and chemoselectivity towards hydrogenation of functionalized nitroarenes and imines; the corresponding aniline derivatives were obtained with high turnover numbers at ambient temperature under 10 atm of H2, and the catalyst is reusable. Ir/CNF-T was also effective for the reductive N-alkylation of anilines with carbonyl compounds.
- Motoyama, Yukihiro,Taguchi, Masahiro,Desmira, Nelfa,Yoon, Seong-Ho,Mochida, Isao,Nagashima, Hideo
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- Synthesis, reactivities, and catalytic properties of iodo-bridged polymeric iridium complexes with flexible carbon chain-bridged bis(tetramethylcyclopentadienyl) ligands
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Dinuclear iridium complexes [(C5Me4)(CH 2)n(C5Me4)][Ir(COD)]2 (2a: n = 2; 2b: n = 3; 2c: n = 4) are obtained from the reactions of the corresponding dilithium salts Li2/sub
- Tan, Xing,Li, Bin,Xu, Shansheng,Song, Haibin,Wang, Baiquan
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p. 3253 - 3261
(2013/07/19)
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- Tertiary alcohols by tandem β-carbolithiation and N→C aryl migration in enol carbamates
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Enol carbamates (O-vinylcarbamates) derived from aromatic or α,β-unsaturated compounds and bearing an N-aryl substituent undergo carbolithiation by nucleophilic attack at the (nominally nucleophilic) β position of the enol double bond. The resulting carbamate-stabilized allylic, propargylic, or benzylic organolithium rearranges with N→C migration of the N-aryl substituent, creating a quaternary carbon α to O. The products may be readily hydrolyzed to yield multiply branched tertiary alcohols in a one-pot tandem reaction, effectively a polarity-reversed nucleophilic β-alkylation-electrophilic α-arylation of an enol equivalent.
- Fournier, Anne M.,Clayden, Jonathan
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supporting information; experimental part
p. 142 - 145
(2012/02/14)
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- Selective copper-promoted cross-coupling of aromatic amines with alkyl boronic acids
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A simple copper-promoted N-monoalkylation of anilines that utilizes alkyl boronic acids as the alkylating partner is presented. The reaction is carried out in refluxing dioxane, and it allows a number of structurally and electronically diverse anilines to be functionalized in a single step. A broad study was carried out to demonstrate the utility of this new methodology for the preparation of phenethylanilines.
- Larrosa, Marta,Guerrero, César,Rodríguez, Ramón,Cruces, Jacobo
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supporting information; experimental part
p. 2101 - 2105
(2010/10/03)
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- Zinc-promoted, iridium catalyzed reductive alkylation of primary amines with aliphatic ketones in aqueous medium
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The reductive alkylation of primary aromatic and aliphatic amines with aliphatic ketones has been achieved in aqueous acidic medium using commercially available, non-activated zinc dust catalyzed by a very small quantity of iridium bromide. Anilines react well in aqueous formic acid, whereas monoalkylamines require 1,4-dioxane as a co-solvent and sulfuric acid as the proton source. A plausible mechanism via low-valent iridium hydride species is proposed.
- da Silva, Renato A.,Bieber, Lothar W.
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scheme or table
p. 689 - 691
(2010/04/02)
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- BICYCLIC IMIDAZOL DERIVATIVES AGAINST FLAVIVIRIDAE
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Disclosed are compounds, compositions and methods for treatingFlaviviridae family virus infections.
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Page/Page column 250
(2008/06/13)
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- A mechanistic comparison between cytochrome P450- and chloroperoxidase-catalyzed N-dealkylation of N,N-dialkyl anilines
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Most peroxidases use histidine as an axial ligand for heme, while chloroperoxidase (CPO) uses a thiolate, which is similar to the ligand employed by cytochrome P450 (P450). Several studies have also shown that, unlike other peroxidases, CPO is capable of carrying out monooxygenation reactions in a similar manner to P450 in addition to typical peroxidase-like reactions. These observations have been attributed to the similarities of the active-site architecture of the two enzymes. Both enzymes have been shown to efficiently catalyze the oxidative N-dealkylation of amines. The similar magnitudes of the kinetic isotope effects determined for P 450- and CPO-catalyzed N-dealkylation of N,N-dimethylaniline have been used to propose that these reactions proceed through similar mechanisms. In this study, we have examined the mechanism of CPO-catalyzed N-dealkylation using a series of radical probes, 4-chloro-N-cyclopropyl-N-alkylanilines 1-3, which we have recently used in the mechanistic studies of P450, and compared the results with those of P450-catalyzed reactions. The results show that P450- and CPO-catalyzed reactions proceed through distinctly different mechanisms. As previously reported, while P 450-catalyzed reactions appear to proceed through a C α-hydrogen abstraction mechanism, CPO-catalyzed reactions proceed through a single electron/proton transfer (SET/H+) mechanism, similar to reactions catalyzed by Horseradish peroxidase (HRP). Thus, CPO may not be a good mechanistic model for P450-catalyzed N-dealkylations. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
- Bhakta, Mehul N.,Wimalasena, Kandatege
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p. 4801 - 4805
(2007/10/03)
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- P450/NADPH/O2- and P450/PhlO-catalyzed N-dealkylations are mechanistically distinct
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A high-valent iron-oxo species analogous to the compound I of peroxidases has been thought to be the activated oxygen species in P450-catalyzed reactions. Spectroscopic characterization of the catalytically competent iron-oxo species in iodosobenzene (PhIO)-supported model reactions and parallels between these model reactions and PhIO- and NADPH/O2-supported P450 reactions have been taken as strong evidence for this proposal. To support this proposal, subtle differences observed in regio- and chemoselectivities, isotope effects, and source of oxygen, etc., between NADPH/O2- and PhIO-supported P450 reactions have been generally attributed to reasons other than the mechanistic differences between the two systems. In the present study, we have used a series of sensitive mechanistic probes, 4-chloro-N-cyclopropyl-N-alkylanilines, to compare and contrast the chemistries of the NADPH/O2- and PhIO-supported purified CYP2B1 N-dealkylation reactions. Herein we present the first experimental evidence to demonstrate that the NADPH/O2- and PhIO-supported P450 N-dealkylations are mechanistically distinct and, thus, the P450/PhIO system may not be a good mechanistic model for P450/NADPH/O2-catalyzed N-dealkylations. Copyright
- Bhakta, Mehul N.,Hollenberg, Paul F.,Wimalasena, Kandatege
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p. 1376 - 1377
(2007/10/03)
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- A Convenient Synthesis of Amines from Phenols
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A simple and convenient method for the conversion of substituted phenols into alkylated amines is described; the reaction proceeds via amide formation and subsequent rearrangement of the amide in the presence of alkali.
- Goswami,Goswami,Borthakur,Rastogi
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p. 424 - 425
(2007/10/03)
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- ONE-POT CHEMOSELECTIVE REDUCTIVE ALKYLATION OF NITROARENES: A NEW GENERAL METHOD OF SYNTHESIS OF ALKYLANILINES.
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A New facile and general synthesis of alkylanilines by one-pot reductive alkylation of nitroarenes is reported.This method is based on the "in situ" reduction by hydrides (LiAlH4 or NaBH4) in the presence of catalytic amounts of Pd/C, of nitronate adducts arising from the conjugate addition of Grignard reagents to mononitroarenes.LiAlH4 showed to be a more efficient but less selective reducing agent than NaBH4.The reaction can be successfully applied to mono, homo and hetero bicyclic systems and allows to introduce a large variety of alkyl chains without isomerisation phenomena.
- Bartoli, Giuseppe,Bosco, Marcella,Pozzo, Renato Dal,Petrini, Marino
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p. 4221 - 4226
(2007/10/02)
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