- Switching Selectivity in Copper-Catalyzed Transfer Hydrogenation of Nitriles to Primary Amine-Boranes and Secondary Amines under Mild Conditions
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A simple and efficient copper-catalyzed selective transfer hydrogenation of nitriles to primary amine-boranes and secondary amines with an oxazaborolidine-BH3 complex is reported. The selectivity control was achieved under mild conditions by switching the solvent and the copper catalysts. More than 30 primary amine-boranes and 40 secondary amines were synthesized via this strategy in high selectivity and yields of up to 95%. The strategy was applied to the synthesis of 15N labeled in 89% yield.
- Song, Hao,Xiao, Yao,Zhang, Zhuohua,Xiong, Wanjin,Wang, Ren,Guo, Liangcheng,Zhou, Taigang
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p. 790 - 800
(2022/01/11)
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- Nickel Complexes Bearing N,N,O-Tridentate Salicylaldiminato Ligand: Efficient Catalysts for Imines Formation via Dehydrogenative Coupling of Primary Alcohols with Amines
-
Treatment of salicylaldiminato ligand L1H-L2H (L1H = 2,4-di-tert-butyl-6-((quinolin-8-ylimino)methyl)phenol; L2H = 2,4-di-tert-butyl-6-(((2-(diethylamino)ethyl)imino)methyl)phenol) with Ni(OAc)2·4H2O in refluxing ethanol afforded nickel complexes [(L1)Ni(OAc)] (1) and [(L2)Ni(OAc)] (2), respectively. Reaction of L3H (L3H = (2,4-di-tert-butyl-6-(((2-(pyridin-2-yl)ethyl)imino)methyl)phenol)) with Ni(OAc)2·4H2O in the presence of excess triethylanmine gave the dual ligands coordinated nickel complex [(L2)2Ni] (3). Complexes 1-3 were well characterized by high-resolution mass spectrometry, infrared spectroscopy, elemental analysis, and X-ray diffraction analysis. All the three Ni(II) complexes exhibited efficient activity and good selectivity in the acceptorless dehydrogenative coupling of alcohols and amines to produce imines and diimines. The present protocol provides an atom-economical and sustainable route for the synthesis of various imine derivatives by employing an earth-abundant nickel salt and easily prepared salicylaldiminato ligands.
- Han, Zhangang,Hao, Zhiqiang,Lin, Jin,Lu, Guo-Liang,Zhang, Junhua,Zhang, Xiaoying
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p. 3843 - 3853
(2021/11/18)
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- 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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- Selenoimidazolium Salts as Supramolecular Reagents for Protein Alkylation
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Se-benzyl selenoimidazolium salts are characterized by remarkable alkyl-transfer potential under physiological conditions. Structure-activity relationship studies show that selective monoalkylation of primary amines depends on supramolecular interactions
- Lim, David,Wen, Xiaojin,Seebeck, Florian P.
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p. 3515 - 3520
(2020/09/21)
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- A practical catalytic reductive amination of carboxylic acids
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We report reductive alkylation reactions of amines using carboxylic acids as nominal electrophiles. The two-step reaction exploits the dual reactivity of phenylsilane and involves a silane-mediated amidation followed by a Zn(OAc)2-catalyzed amide reduction. The reaction is applicable to a wide range of amines and carboxylic acids and has been demonstrated on a large scale (305 mmol of amine). The rate differential between the reduction of tertiary and secondary amide intermediates is exemplified in a convergent synthesis of the antiretroviral medicine maraviroc. Mechanistic studies demonstrate that a residual 0.5 equivalents of carboxylic acid from the amidation step is responsible for the generation of silane reductants with augmented reactivity, which allow secondary amides, previously unreactive in zinc/phenylsilane systems, to be reduced.
- Andrews, Keith G.,Denton, Ross M.,Hirst, David J.,Stoll, Emma L.,Tongue, Thomas,Valette, Damien
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p. 9494 - 9500
(2020/10/02)
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- Three novel Cd(II) dithiocarbamate complexes: synthesis, structural diversity and fluorescence properties
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Three new homoleptic cadmium (II) dithiocarbamate complexes having molecular formula [Cd(KL)2], (KL1 = C15H13N1F1S2) (1); (L2 = C13H11N1F1S2) (2); (L3 = C11H14N1O1S2) (3), have been synthesized and characterized by elemental analysis, spectroscopy (IR, 1H and 13CNMR and UV–Vis). Single crystal X-ray studies confirm that the complex 1 crystallises in Orthorhombic with space group Pna21 and holding dimeric structure. In this complex Cd2+ having distorted octahedral geometry about the metal centre forms 1D coordination polymeric structures. The dimeric form of complex 2 and 3 crystallizes in triclinic crystal lattice with space group P-1.
- Singh, Ravi Pratap,Maurya, Vinay Kumar,Prasad, Lal Bahadur,Siddiqui, Kafeel Ahmad
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p. 2867 - 2876
(2020/07/03)
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- A proton-responsive annulated mesoionic carbene (MIC) scaffold on IR complex for proton/hydride shuttle: An experimental and computational investigation on reductive amination of aldehyde
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A Cp*Ir(III) complex (1) bearing a proton-responsive hydroxy unit on an annulated imidazo[1,2-a][1,8]naphthyridine based mesoionic carbene scaffold was synthesized by two different synthetic routes. The molecular structure of 1 revealed an anionic lactam form of the ligand. The acid?base equilibrium between the lactam-lactim tautomers on the ligand scaffold was examined by 1H NMR and UV?vis spectra. The pKa of the appendage ?OH group in the lactim form of 1 was estimated to assess the proton transfer property of the catalyst. The catalytic efficacy of 1 for reductive amination of aldehyde was evaluated by utilizing three different hydrogen sources: molecular H2iPrOH/KOtBu combination, and HCOOH/Et3N (5:2) azeotropic mixture. The HCOOH/Et3N (5:2) azeotropic mixture rotocol was found to be the best amon the three different h dro enation methods. Catalyst 1 hydrogenates imines chemoselectively over carbonyls under the reaction conditions. A range of aldehydes was reductively aminated to the corresponding secondary amines using the HCOOH/Et3N (5:2) azeotropic mixture. Further, catalyst 1 showed high efficiency for the reduction of a wide variety of N-heterocyclic imine derivatives. The lactam-lactim tautomerization of the ligand system is proposed for direct hydrogenation, whereas only the lactam form operates in the strongly basic medium (iPrOH/KOtBu). Under HCOOH/Et3N (5:2) conditions, the lactam scaffold is not protonated; rather, an outer-sphere hydride transfer from formate to the Ir is proposed, which is supported by 1H NMR and DFT calculations. Finally, ligand-promoted hydride transfer from metal-hydride to the protonated imine affords the corresponding amine. A close agreement between the experimentally estimated and computed thermodynamic/kinetic parameters gives credence to the metal-ligand cooperative mechanism for the imine hydrogenation reaction using the HCOOH/Et3N (5:2) azeotropic mixture.
- Bera, Jitendra K.,Daw, Prosenjit,Din Reshi, Noor U.,Ehmann, Kira R.,H?lscher, Markus,Leitner, Walter,Pandey, Pragati
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p. 3849 - 3863
(2020/11/23)
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- Selective Synthesis of Secondary Amines from Nitriles by a User-Friendly Cobalt Catalyst
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Selective hydrogenation/reductive amination of nitriles to secondary amines catalyzed by an inexpensive and user-friendly cobalt complex, (Xantphos)CoCl2, is reported. The use of (Xantphos)CoCl2 and ammonia borane (NH3?BH3) combination affords the selective reduction of nitriles to symmetrical secondary amines, whereas the employment of (Xantphos)CoCl2 and dimethylamine borane (Me2NH?BH3) along with external amines produce unsymmetrical secondary amines and tertiary amines. The general applicability of this methodology is demonstrated by the synthesis of 43 symmetrical and unsymmetrical secondary and tertiary amines bearing diverse functionalities. (Figure presented.).
- Sharma, Dipesh M.,Punji, Benudhar
-
supporting information
p. 3930 - 3936
(2019/07/12)
-
- PENTAFLUOROPHENYL SULFONAMIDE COMPOUNDS, COMPOSITIONS AND USES THEREOF
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The present application relates to sulfonamide containing compounds of Formulae (I) and (II) and compositions containing said compounds effective in the treatment of cell proliferative disorders, in particular cancer, and various methods of use thereof.
- -
-
Paragraph 00134; 00139
(2019/04/16)
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- Photocatalyzed cascade Meerwein addition/cyclization of: N -benzylacrylamides toward azaspirocycles
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A visible-light-induced cascade Meerwein addition/cyclization of alkenes involving C-F bond cleavage was developed. This method offers a rapid access to azaspirocyclic cyclohexadienones from N-benzylacrylamides via C-F bond cleavage applying H2O as an external oxygen source, allowing for the incorporation of various aromatic moieties originating from aryldiazonium salts.
- Yuan, Li,Jiang, Sheng-Ming,Li, Zeng-Zeng,Zhu, Yong,Yu, Jian,Li, Lan,Li, Ming-Zhu,Tang, Shi,Sheng, Rui-Rong
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supporting information
p. 2406 - 2410
(2018/04/12)
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- Simple Metal-Free Direct Reductive Amination Using Hydrosilatrane to Form Secondary and Tertiary Amines
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This work describes the use of cheap, safe, and easy-to-handle hydrosilatrane as the reductant in direct reductive amination reactions. This efficient method enables a facile, metal-free access to secondary and tertiary amines from a wide range of aldehydes and ketones, with the synthesis of tertiary amines requiring no additives at all. This reaction demonstrates excellent functional group tolerance, chemoselectivity, and scalability. (Figure presented.).
- Varjosaari, Sami E.,Skrypai, Vladislav,Suating, Paolo,Hurley, Joseph J. M.,Lio, Ashley M. De,Gilbert, Thomas M.,Adler, Marc J.
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supporting information
p. 1872 - 1878
(2017/06/09)
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- Expanding the Boundaries of Water-Tolerant Frustrated Lewis Pair Hydrogenation: Enhanced Back Strain in the Lewis Acid Enables the Reductive Amination of Carbonyls
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The development of a boron/nitrogen-centered frustrated Lewis pair (FLP) with remarkably high water tolerance is presented. As systematic steric tuning of the boron-based Lewis acid (LA) component revealed, the enhanced back-strain makes water binding increasingly reversible in the presence of relatively strong base. This advance allows the limits of FLP's hydrogenation to be expanded, as demonstrated by the FLP reductive amination of carbonyls. This metal-free catalytic variant displays a notably broad chemoselectivity and generality.
- Dorkó, éva,Szabó, Márk,Kótai, Bianka,Pápai, Imre,Domján, Attila,Soós, Tibor
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supporting information
p. 9512 - 9516
(2017/08/01)
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- A segmented flow platform for on-demand medicinal chemistry and compound synthesis in oscillating droplets
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We report an automated flow chemistry platform that can efficiently perform a wide range of chemistries, including single/multi-phase and single/multi-step, with a reaction volume of just 14 μL. The breadth of compatible chemistries is successfully demonstrated and the desired products are characterized, isolated, and collected online by preparative HPLC/MS/ELSD.
- Hwang, Ye-Jin,Coley, Connor W.,Abolhasani, Milad,Marzinzik, Andreas L.,Koch, Guido,Spanka, Carsten,Lehmann, Hansjoerg,Jensen, Klavs F.
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p. 6649 - 6652
(2017/07/10)
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- Efficient and Selective Hydrosilylation of Secondary and Tertiary Amides Catalyzed by an Iridium(III) Metallacycle: Development and Mechanistic Investigation
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Readily accessible cationic IrIII metallacycles catalyze efficiently the chemoselective hydrosilylation of tertiary and secondary amides to amines. The catalyst described herein operates at low loadings using inexpensive 1,1,3,3-tetramethyldisiloxane and allows fast reactions with high yields, selectivities, and turnover numbers. A transient iminium intermediate has been observed for the first time by using mass spectrometry, and the activation of the catalyst and the silane reagent have been studied by using DFT calculations. These fundamental insights support the present and future improvements of IrIII metallacycles through proper ligand modifications and enable further broad applications of catalysts based on metallacycles.
- Corre, Yann,Trivelli, Xavier,Capet, Frédéric,Djukic, Jean-Pierre,Agbossou-Niedercorn, Francine,Michon, Christophe
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p. 2009 - 2017
(2017/06/13)
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- Expanding Water/Base Tolerant Frustrated Lewis Pair Chemistry to Alkylamines Enables Broad Scope Reductive Aminations
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Lower Lewis acidity boranes demonstrate greater tolerance to combinations of water/strong Br?nsted bases than B(C6F5)3, this enables Si?H bond activation by a frustrated Lewis pair (FLP) mechanism to proceed in the presence of H2O/alkylamines. Specifically, BPh3has improved water tolerance in the presence of alkylamines as the Br?nsted acidic adduct H2O–BPh3does not undergo irreversible deprotonation with aliphatic amines in contrast to H2O–B(C6F5)3. Therefore BPh3is a catalyst for the reductive amination of aldehydes and ketones with alkylamines using silanes as reductants. A range of amines inaccessible using B(C6F5)3as catalyst, were accessible by reductive amination catalysed by BPh3via an operationally simple methodology requiring no purification of BPh3or reagents/solvent. BPh3has a complementary reductive amination scope to B(C6F5)3with the former not an effective catalyst for the reductive amination of arylamines, while the latter is not an effective catalyst for the reductive amination of alkylamines. This disparity is due to the different pKavalues of the water–borane adducts and the greater susceptibility of BPh3species towards protodeboronation. An understanding of the deactivation processes occurring using B(C6F5)3and BPh3as reductive amination catalysts led to the identification of a third triarylborane, B(3,5-Cl2C6H3)3, that has a broader substrate scope being able to catalyse the reductive amination of both aryl and alkyl amines with carbonyls.
- Fasano, Valerio,Ingleson, Michael J.
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supporting information
p. 2217 - 2224
(2017/02/18)
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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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- Selective Activation of Alcohols in the Presence of Reactive Amines over Intermetallic PdZn: Efficient Catalysis for Alcohol-Based N-Alkylation of Various Amines
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Pd-based intermetallic compounds supported on Al2O3 (PdxMy/Al2O3, where M = Bi, Cu, Fe, Ga, In, Pb, Sn, or Zn) were prepared and tested as catalysts for the selective activation of alcohols in the presence of reactive amines, which is highly challenging and is the key strategy for alcohol-based N-alkylation of amines. Although the Pd/Al2O3 catalyst exhibited a high catalytic activity, undesired side reactions such as amine dimerization (via amine activation) and C-O bond scission occurred, resulting in a poor yield of the N-alkylation product. In contrast, the PdZn/Al2O3 catalyst acted as an efficient catalyst for this reaction, displaying high catalytic activities, selectivities, and atom efficiencies and a wide substrate scope. Detailed kinetic and computational studies revealed that the relative affinity of Pd for alcohol and amine drastically changes by the formation of a PdZn intermetallic phase. On monometallic Pd, the adsorption and activation of amines are preferred over those of alcohols in terms of thermodynamic and kinetic aspects, respectively. However, this trend is inverted on PdZn, allowing preferential adsorption and activation of alcohols and, hence, selective N-alkylation.
- Furukawa, Shinya,Suzuki, Ryohei,Komatsu, Takayuki
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p. 5946 - 5953
(2016/09/09)
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- Reductive Transformations of Carbonyl Compounds Catalyzed by Rhodium Supported on a Carbon Matrix by using Carbon Monoxide as a Deoxygenative Agent
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An efficient method for the rhodium on carbon matrix catalyzed preparation of secondary and tertiary amines, cyanoesters, and nitriles through the reductive amination/alkylation of carbonyl compounds was developed, including a convenient procedure for the tandem formal reductive addition of acetonitrile to aldehydes. The catalyst could be reused, and at least three consecutive reaction cycles were performed with comparable efficiency. The method was shown to be compatible with functional groups prone to reduction by hydrogen and complex hydrides. Beyond the matrix: An efficient method for the rhodium on carbon matrix catalyzed preparation of secondary and tertiary amines, cyanoesters, and nitriles through the reductive amination/alkylation of carbonyl compounds is developed, including a convenient procedure for the tandem formal reductive addition of acetonitrile to aldehydes. TON=turnover number.
- Yagafarov, Niyaz Z.,Usanov, Dmitry L.,Moskovets, Alexey P.,Kagramanov, Nikolai D.,Maleev, Victor I.,Chusov, Denis
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p. 2590 - 2593
(2015/09/15)
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- Graphene-supported NiPd alloy nanoparticles: A novel and highly efficient heterogeneous catalyst system for the reductive amination of aldehydes
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A novel and highly efficient heterogeneous catalytic reductive amination of aldehydes is described. The recently developed graphene supported NiPd alloy nanoparticle (G-NiPd) catalyst using ammonia borane (AB) as a green, stable and safe hydrogen donor was used in a water/methanol mixture (v/v = 2/3) under ambient conditions. The catalytic system was successfully applied in the reductive amination of various substituted aldehydes with amines and the corresponding products were obtained in (up to) 99% yield in 6 h. The G-NiPd catalyst could be recycled up to five times without any significant loss in the product yield.
- Ni?anci, Bilal,Ganjehyan, Khadijeh,Metin, ?nder,Da?tan, Arif,T?r?k, Béla
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p. 191 - 197
(2015/09/22)
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- TERTIARY AMINES FOR USE IN THE TREATMENT OF CARDIAC DISORDERS
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The present invention relates to tertiary amines of formula (I) for use in therapy, particularly for use in treating cardiovascular disorders. The compounds have been found to regulate phospholamban phosphorylation by interfering with the A-kinase anchor protein 18delta (AKAP185) binding to the PKA substrate phospholamban. The compounds share a tri(alkylaryl/alkylheteroaryl) amine structure.
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Page/Page column 113
(2013/12/03)
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- An efficient palladium-catalyzed N-alkylation of amines using primary and secondary alcohols
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PdCl2 in the presence of dppe or Xantphos(t-Bu) as the ligand is found to be an efficient catalyst for the N-alkylation of various primary and cyclic secondary amines using primary alcohols at 90-130 C under neat conditions. Interestingly, good to excellent yields were achieved when more challenging secondary alcohols were used as alkylating agents at 130-150 C. The reaction could be easily scaled up, as demonstrated for a 10 mmol scale achieving yields up to 90% with a TON of 900.
- Dang, Tuan Thanh,Ramalingam, Balamurugan,Shan, Siah Pei,Seayad, Abdul Majeed
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p. 2536 - 2540
(2013/11/19)
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- Synthesis of α-amino acids through samarium(II) iodide promoted reductive coupling of nitrones with CO2
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Several N-benzylnitrones reacted with carbon dioxide in the presence of samarium(II) iodide leading to α-amino acids as the products of reductive C-C coupling. The best selectivities were observed at a carbon dioxide pressure of 50 bar at ambient temperature. The influences of different functional groups in the nitrone backbone and of the coordinating additives to samarium(II) iodide on the product distribution were investigated. The racemic α-amino acids were obtained in up to 70% yield based on HPLC data. A novel approach to the synthesis ofα-amino acids is disclosed, involvingC-carboxylation of nitrones by gaseous CO2 under reductive coupling reaction conditions (SmI2, 0.1 M in THF) at ambient temperature and 50 bar of CO 2 pressure. Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
- Prikhod'Ko, Alexander,Walter, Olaf,Zevaco, Thomas A.,Garcia-Rodriguez, Jaime,Mouhtady, Omar,Py, Sandrine
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supporting information; experimental part
p. 3742 - 3746
(2012/09/25)
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- Iridium-catalyzed reduction of secondary amides to secondary amines and imines by diethylsilane
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Catalytic reduction of secondary amides to imines and secondary amines has been achieved using readily available iridium catalysts such as [Ir(COE) 2Cl]2 with diethylsilane as reductant. The stepwise reduction to secondary amine proceeds through an imine intermediate that can be isolated when only 2 equiv of silane is used. This system requires low catalyst loading and shows high efficiency (up to 1000 turnovers at room temperature with 99% conversion have been attained) and an appreciable level of functional group tolerance.
- Cheng, Chen,Brookhart, Maurice
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supporting information; experimental part
p. 11304 - 11307
(2012/09/05)
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- A general and selective copper-catalyzed reduction of secondary amides
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In situ-generated cationic copper/pybox catalyst systems allow for the selective reduction of secondary amides into the corresponding amines under mild conditions. This novel protocol has a wide substrate scope and shows good functional group tolerance. The Royal Society of Chemistry 2012.
- Das, Shoubhik,Join, Benoit,Junge, Kathrin,Beller, Matthias
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p. 2683 - 2685
(2012/04/04)
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- Zinc-catalyzed chemoselective reduction of tertiary and secondary amides to amines
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General and convenient procedures for the catalytic hydrosilylation of secondary and tertiary amides under mild conditions have been developed. In the presence of inexpensive zinc catalysts, tertiary amides are easily reduced by applying monosilanes. Key to success for the reduction of the secondary amides is the use of zinc triflate and disilanes with dual Si-H moieties. The presented hydrosilylations proceed with excellent chemoselectivity in the presence of sensitive ester, nitro, azo, nitrile, olefins, and other functional groups, thus making the method attractive for organic synthesis.
- Das, Shoubhik,Addis, Daniele,Junge, Kathrin,Beller, Matthias
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experimental part
p. 12186 - 12192
(2011/11/07)
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- Secondary amines: Synthesis and effect of length of spacer linking two phenyl rings on biological activity
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N-Benzyl benzylamines (1a-11a) and N-benzyl anilines (1b-11b) were synthesized by sodium borohydride reduction of aldimines of benzylamine and aniline respectively. The products were characterized on the basis of elemental analysis and spectral studies and screened for antifungal potential against four fungi and evaluated for nematicidal activity against two nematodes. The former compounds were found to be more effective as compared to the latter thus indicating an enhancement of biological activity due to introduction of an extra methylene group between two phenyl rings of aromatic secondary amines.
- Rani, Neeraj,Sharma,Kaul,Manrao
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experimental part
p. 1041 - 1044
(2009/12/24)
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- Aza-peptidyl Michael acceptors. A new class of potent and selective inhibitors of asparaginyl endopeptidases (legumains) from evolutionarily diverse pathogens
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Aza-peptide Michael acceptors with the general structure of Cbz-Ala-Ala-AAsn-trans-CH=CHCOR are a new class of inhibitors specific for the asparaginyl endopeptidases (AE) (legumains). Structure-activity relationships (SARs) were characterized for a set of 31 aza-peptide Michael acceptors with AEs derived from three medically important parasites: the protist Trichomonas vaginalis, the hard tick Ixodes ricinus, and the flatworm Schistosoma mansoni. Despite arising from phylogenetically disparate organisms, all three AEs shared a remarkably similar SAR with lowest IC50 values extending into the picomolar range. The results suggest an evolutionary constraint on the topography of the prime side of the active site. SAR also revealed that esters in the P1′ position are more potent than disubstituted amides and that monosubstituted amides and alkyl derivatives show little or no inhibition. The preferred P1′ residues have aromatic substituents. Aza-asparaginyl Michael acceptors react with thiols, which provides insight into the mechanism of their inhibition of asparaginyl endopeptidases.
- G?tz, Marion G.,James, Karen Ellis,Hansell, Elizabeth,Dvo?ák, Jan,Seshaadri, Amritha,Sojka, Daniel,Kopá?ek, Petr,McKerrow, James H.,Caffrey, Conor R.,Powers, James C.
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p. 2816 - 2832
(2008/12/22)
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- PROPENOYL HYDRAZIDES
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The present disclosure provides compositions for inhibiting proteases, methods for synthesizing the compositions, and methods of using the disclosed protease inhibitors. Aspects of the disclosure include a peptidyl propenoyl hydrazide compositions that inhibit proteases, for example cysteine proteases, either in vivoor in vitro.
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Page/Page column 35
(2008/06/13)
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- CHEMICAL INDUCTION OF POLY-CIS CAROTENOID BIOSYNTHESIS
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Key Word Index - Citrus paradisi; Rutaceae; Marsh white seedless grapefruit; carotenoid biosynthesis; bioregulators; poly-cis carotenoids; carotenoids; prolycopene.A new class of synthetic bioregulators is reported which cause the accumulation of poly-cis carotenoids in the flavedo of Marsh white seedless grapefruit.The compounds tested were all secondary amines: dibenzylamine, substituted dibenzylamines (4-F; 4-Cl; 4-Br; 2-, 3- and 4-Me; 4-NO2; 4-CN; 4-Cl; 4'-Me; 4-Me, 4'-NO2), N-benzyl phenethylamine and N-benzyl 2-naphthalenemethylamine.The most effective, 4-chlorodibenzylamine, caused the accumulation of 74 μg/g dry wt of poly-cis carotenoids.Prolycopene was the predominant pigment but substantial amounts of proneurosporene, poly-cis-γ-carotenes and other cis carotenes were also present.The mode of action of these new bioregulators is probably gene derepression, the same as that of the lycopene inducers.However, the secondary amines probably derepress a recessive gene governing the biosynthesis of poly-cis carotenoids; whereas, the lycopene inducers derepress the dominant gene that gives rise to the normall all-trans carotenoids.The new compounds did not seem to inhibit the cyclase(s), as the lycopene inducers do.
- Poling, Stephen M.,Hsu, Wan-Jean,Yokoyama, Henry
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p. 1677 - 1680
(2007/10/02)
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- Fibrin stabilizing factor inhibitors. 12. 5 dibenzylaminopentylamine and related compounds, a new type of FSF inhibitors
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A series of omega dibenzylaminoalkylamines and related compounds have been prepared and tested as inhibitors of fibrin cross linking. This structural type was chosen in an attempt to develop noncompetitive inhibitors of fibrinoligase. By the combination o
- Hoffmann,Stenberg,Ljunggren,Svensson,Nilsson
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p. 278 - 284
(2007/10/04)
-