- Cobalt-Catalyzed Deoxygenative Hydroboration of Nitro Compounds and Applications to One-Pot Synthesis of Aldimines and Amides
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The commercially available and bench-stable Co(acac)2 ligated with bis[(2-diphenylphosphino)phenyl] ether (dpephos) was employed for selective room temperature hydroboration of nitro compounds with HBPin (TOF up to 4615 h?1), tolerating halide, hydroxy, amino, ether, ester, lactone, amide and heteroaromatic functionalities. These reactions offered a direct access to a variety of N-borylamines RN(H)BPin, which were in situ treated with aldehydes and carboxylic acids to produce a series of aldimines and secondary carboxamides without the need for dehydrating and/or coupling reagents. Combination of these transformations in a sequential one-pot manner allowed for direct and selective synthesis of aldimines and secondary carboxamides from readily available and inexpensive nitro compounds.
- Gudun, Kristina A.,Hayrapetyan, Davit,Khalimon, Andrey Y.,Segizbayev, Medet,Slamova, Ainur,Zakarina, Raikhan
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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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- FUNCTIONALIZED HETEROCYCLIC COMPOUNDS AS MODULATORS OF STIMULATOR OF INTERFERON GENES (STING)
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The present invention relates to compound-linker constructs and antibody-drug-conjugates of compounds of formula (I) that are useful as modulators of STING (Stimulator of Interferon Genes).
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Page/Page column 267
(2021/06/22)
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- Hydrosilylative reduction of primary amides to primary amines catalyzed by a terminal [Ni-OH] complex
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A terminal [Ni-OH] complex1, supported by triflamide-functionalized NHC ligands, catalyzes the hydrosilylative reduction of a range of primary amides into primary amines in good to excellent yields under base-free conditions with key functional group tolerance. Catalyst1is also effective for the reduction of a variety of tertiary and secondary amides. In contrast to literature reports, the reactivity of1towards amide reduction follows an inverse trend,i.e., 1° amide > 3° amide > 2° amide. The reaction does not follow a usual dehydration pathway.
- Bera, Jitendra K.,Pandey, Pragati
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supporting information
p. 9204 - 9207
(2021/09/20)
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- Cyclic (Alkyl)(amino)carbene Ligand-Promoted Nitro Deoxygenative Hydroboration with Chromium Catalysis: Scope, Mechanism, and Applications
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Transition metal catalysis that utilizes N-heterocyclic carbenes as noninnocent ligands in promoting transformations has not been well studied. We report here a cyclic (alkyl)(amino)carbene (CAAC) ligand-promoted nitro deoxygenative hydroboration with cost-effective chromium catalysis. Using 1 mol % of CAAC-Cr precatalyst, the addition of HBpin to nitro scaffolds leads to deoxygenation, allowing for the retention of various reducible functionalities and the compatibility of sensitive groups toward hydroboration, thereby providing a mild, chemoselective, and facile strategy to form anilines, as well as heteroaryl and aliphatic amine derivatives, with broad scope and particularly high turnover numbers (up to 1.8 × 106). Mechanistic studies, based on theoretical calculations, indicate that the CAAC ligand plays an important role in promoting polarity reversal of hydride of HBpin; it serves as an H-shuttle to facilitate deoxygenative hydroboration. The preparation of several commercially available pharmaceuticals by means of this strategy highlights its potential application in medicinal chemistry.
- Zhao, Lixing,Hu, Chenyang,Cong, Xuefeng,Deng, Gongda,Liu, Liu Leo,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 1618 - 1629
(2021/01/25)
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- Ru-Catalyzed Transfer Hydrogenation of Nitriles, Aromatics, Olefins, Alkynes and Esters
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This paper reports the preparation of new ruthenium(II) complexes supported by a pyrazole-phosphine ligand and their application to transfer hydrogenation of various substrates. These Ru complexes were found to be efficient catalysts for the reduction of nitriles and olefins. Heterocyclic compounds undergo transfer hydrogenation with good to moderate yields, affording examples of unusual hydrogenation of all-carbon-rings. Internal alkynes with bulky substituents show selective reduction to olefins with the unusual E–selectivity. Esters with strong electron-withdrawing groups can be reduced to the corresponding alcohols, if ethanol is used as the solvent. Possible mechanisms of hydrogenation and olefin isomerization are suggested on the basis of kinetic studies and labelling experiments.
- Alshakova, Iryna D.,Gabidullin, Bulat,Nikonov, Georgii I.
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p. 4860 - 4869
(2018/10/02)
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- Cobalt-Catalyzed and Lewis Acid-Assisted Nitrile Hydrogenation to Primary Amines: A Combined Effort
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The selective hydrogenation of nitriles to primary amines using a bench-stable cobalt precatalyst under 4 atm of H2 is reported herein. The catalyst precursor was reduced in situ using NaHBEt3, and the resulting Lewis acid formed, BEt3, was found to be integral to the observed catalysis. Mechanistic insights gleaned from para-hydrogen induced polarization (PHIP) transfer NMR studies revealed that the pairwise hydrogenation of nitriles proceeded through a Co(I/III) redox process.
- Tokmic, Kenan,Jackson, Bailey J.,Salazar, Andrea,Woods, Toby J.,Fout, Alison R.
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p. 13554 - 13561
(2017/10/05)
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- A proton-switchable bifunctional ruthenium complex that catalyzes nitrile hydroboration
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A new bifunctional pincer ligand framework bearing pendent proton-responsive hydroxyl groups was prepared and metalated with Ru(II) and subsequently isolated in four discrete protonation states. Stoichiometric reactions with H2 and HBPin showed facile E-H (E = H or BPin) activation across a Ru(II)-O bond, providing access to unusual Ru-H species with strong interactions with neighboring proton and boron atoms. These complexes were found to promote the catalytic hydroboration of ketones and nitriles under mild conditions, and the activity was highly dependent on the ligand's protonation state. Mechanistic experiments revealed a crucial role of the pendent hydroxyl groups for catalytic activity.
- Geri, Jacob B.,Szymczak, Nathaniel K.
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p. 12808 - 12814
(2015/10/28)
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- Transfer hydrogenation of ketones, nitriles, and esters catalyzed by a half-sandwich complex of ruthenium
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Half-sandwich complexes [Cp(PiPr3)Ru(CH3CN)2]PF6 (1; Cp = cyclopentadienyl) and [Cp(phen)Ru(CH3CN)]PF6 (2; Cp = pentamethylcyclopentadienyl, phen = phenanthroline) catalyse the transfer hydrogenation of ketones to alcohols, aldimines to amines, and nitriles to imines under mild conditions. In the latter process, the imine products come from the coupling of the amines formed initially with acetone derived from the reducing solvent (isopropanol). Among functionally substituted nitriles, the aldo and keto groups are reduced concomitantly with the cyano group, whereas ester and amido groups are tolerated. Amides and alkyl esters are not reduced under these conditions even upon heating to 70°C. However, phenylbenzoates and trifluoroacetates are reduced to alcohols. Kinetic studies on the reduction of acetophenone in isopropanol established that the reaction is first order in both the substrate and the alcohol. Stoichiometric mechanistic studies showed the formation of a hydride species. A hydride mechanism was proposed to account for these observations.
- Lee, Sun-Hwa,Nikonov, Georgii I.
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p. 107 - 113
(2015/01/30)
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- APPLICATIONS OF N6-SUBSTITUTED ADENOSINE DERIVATIVE AND N6-SUBSTITUTED ADENINE DERIVATIVE TO CALMING, HYPNOSES, CONVULSION RESISTANCE, EPILEPTIC RESISTANCE, PARKINSON DISEASE RESISTANCE, AND DEMENTIA PREVENTION AND TREATMENT
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PROBLEM TO BE SOLVED: To prepare analgesics, hypnotic agents, anticonvulsant agents, antiepileptics, antiparkinson drugs, dementia prophylactics, and health care food. SOLUTION: The present invention relates to an N6-substituted adenosine derivative and an N6-substituted adenine derivative selected from the group consisting of specific compounds. The present invention also relates to a pharmaceutical composition at least comprising a therapeutically effective amount of the compounds and a pharmaceutically acceptable carrier. The invention further relates to the compounds used in preparation of analgesics, hypnotic agents, anticonvulsant agents, antiepileptics, antiparkinson drugs, dementia prophylactics, and health care food. COPYRIGHT: (C)2016,JPO&INPIT
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Paragraph 0098
(2018/10/27)
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- A practical procedure for reduction of primary, secondary and tertiary amides to amines
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A mild and general procedure for reduction of primary, secondary, and tertiary amides using catalytic triruthenium dodecacarbonyl and 1,1,3,3-tetramethyldisiloxane as reductant is described. The reaction is tolerant of numerous functional groups, and the amine products can often be isolated by direct crystallization as hydrochloride salts. The catalyst and silane are commercially available, air stable, and inexpensive, making the procedure accessible for both laboratory and large-scale applications. Copyright
- Reeves, Jonathan T.,Tan, Zhulin,Marsini, Maurice A.,Han, Zhengxu S.,Xu, Yibo,Reeves, Diana C.,Lee, Heewon,Lu, Bruce Z.,Senanayake, Chris H.
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supporting information
p. 47 - 52
(2013/03/13)
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- N6-SUBSTITUTED ADENOSINE DERIVATIVES AND N6-SUBSTITUTED ADENINE DERIVATIVES AND USES THEREOF
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The present invention provides N6-substituted adenosine derivatives and N6-substituted adenine derivatives, manufacturing methods thereof, a pharmaceutical composition comprising the said compounds above, and uses of these compounds in manufacturing medicaments and health-care products for treating insomnia, convulsion, epilepsy, and Parkinson's diseases, and preventing and treating dementia.
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Paragraph 0101
(2013/03/26)
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- N6-SUBSTITUTED ADENOSINE DERIVATIVES, N6-SUBSTITUTED ADENINE DERIVATIVES AND USES THEREOF
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The present invention provides N6-substituted adenosine derivatives and N6-substituted adenine derivatives, manufacturing methods thereof, a pharmaceutical composition comprising the said compounds above, and uses of of these compounds in manufacturing medicaments and health-care products for treating insomnia, convulsion, epilepsy, and Parkinson's diseases, and preventing and treating dementia.
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Page/Page column 40
(2012/11/06)
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- FRICTIONLESS MOLECULAR ROTARY MOTORS
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A rotaxane consisting of a cucurbituril and an uncharged guest molecule, having low or null affinity therebetween is provided as well as processes for providing the same. Various uses as energy converters (“frictionless” molecular motors), biochips and biosensors using the same are also provided.
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Page/Page column 33
(2010/02/17)
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- Substituent effects. 14. Anomalous dissociation constants in water-organic solvent mixtures: benzylammonium ions and related systems
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Thermodynamic dissociation constants in various water-organic solvent mixtures are given for benzylammonium, benzyldialkylammonium, and (2-phenylethyl)ammonium ions.Deviations from the Hammett equation (Eqn. 1) are similar to those observed for carboxylic acids, but of opposite sign.The extended Hammett equation (Eqn. 3), containing the hydrophobic constant, ?, yields good correlations.Derived secondary normal sigma values are exemplified.
- Hoefnagel, A. J.,Vos, R. H. de,Wepster, B. M.
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- SYNTHESIS AND PROPERTIES OF 3- AND 4-AMINOBENZYLAMINE DERIVATIVES
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Derivatives of 3- and 4-aminobenzylamine substituted by chlorine atom, methyl or methoxyl group in the ring position 2, 4, 5 or 6 were synthesized.Structures of the compounds obtained were confirmed by spectroscopic (IR, NMR) and physico-chemical methods. pKa values were determined for the prepared amines and correlated with ? constants of substituents.The values of ?n meta and ?n para were found for the methylammonium group.
- Kraska, Jan,Teodorczyk, Zygmunt
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p. 1025 - 1034
(2007/10/02)
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