- Phosphine-Free Manganese Catalyst Enables Selective Transfer Hydrogenation of Nitriles to Primary and Secondary Amines Using Ammonia-Borane
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Herein we report the synthesis of primary and secondary amines by nitrile hydrogenation, employing a borrowing hydrogenation strategy. A class of phosphine-free manganese(I) complexes bearing sulfur side arms catalyzed the reaction under mild reaction conditions, where ammonia-borane is used as the source of hydrogen. The synthetic protocol is chemodivergent, as the final product is either primary or secondary amine, which can be controlled by changing the catalyst structure and the polarity of the reaction medium. The significant advantage of this method is that the protocol operates without externally added base or other additives as well as obviates the use of high-pressure dihydrogen gas required for other nitrile hydrogenation reactions. Utilizing this method, a wide variety of primary and symmetric and asymmetric secondary amines were synthesized in high yields. A mechanistic study involving kinetic experiments and high-level DFT computations revealed that both outer-sphere dehydrogenation and inner-sphere hydrogenation were predominantly operative in the catalytic cycle.
- Sarkar, Koushik,Das, Kuhali,Kundu, Abhishek,Adhikari, Debashis,Maji, Biplab
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p. 2786 - 2794
(2021/03/03)
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- An imidazolin-2-iminato ligand organozinc complex as a catalyst for hydroboration of organic nitriles
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The reaction of diethylzinc with imidazolin-2-imines (ImRNH, R = Dipp (2,6-diisopropylphenyl)), Mes (2,4,6-trimethylphenyl), and tBu (tert-butyl) afforded the corresponding dimeric zinc(ii) imidazolin-2-iminato complexes [{(ImRN)Zn(CH2CH3)}2] (R = Dipp, 1a; R = Mes, 1b; R = tBu, 1c). The zinc complexes were characterised using spectroscopic techniques and the molecular structure of complex 1b was established by single-crystal X-ray diffraction analysis. Complex 1c was used as a catalyst for the chemo-selective hydroboration of organic nitriles with pinacolborane (HBpin) at ambient temperature to obtain diborylamines of a broad substrate scope in high yield. Zinc complex 1c exhibits a versatile substrate scope and good functional group tolerance for catalytic hydroboration reactions. A most plausible mechanism is proposed on the basis of the kinetic study.
- Das, Suman,Bhattacharjee, Jayeeta,Panda, Tarun K.
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p. 16812 - 16818
(2019/11/14)
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- Catalytic Staudinger Reduction at Room Temperature
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We report an efficient catalytic Staudinger reduction at room temperature that enables the preparation of a structurally diverse set of amines from azides in excellent yields. The reaction is based on the use of catalytic amounts of triphenylphosphine as a phosphine source and diphenyldisiloxane as a reducing agent. Our catalytic Staudinger reduction exhibits a high chemoselectivity, as exemplified by reduction of azides over other common functionalities, including nitriles, alkenes, alkynes, esters, and ketones.
- Lenstra, Danny C.,Wolf, Joris J.,Mecinovi?, Jasmin
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p. 6536 - 6545
(2019/05/24)
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- Switching the Selectivity of Cobalt-Catalyzed Hydrogenation of Nitriles
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Previous studies of base metals for catalytic hydrogenation of nitriles to primary amines or secondary aldimines focus on designing complexes with elaborate structures. Herein, we report "twin" catalytic systems where the selectivity of nitrile hydrogenation can be tuned by including or omitting the ligand HN(CH2CH2PiPr2)2 (iPrPNHP). Simply treating CoBr2 with NaHBEt3 generates cobalt particles, which can catalyze the hydrogenation of nitriles to primary amines with high selectivity and broad functional group tolerance. Ligating CoBr2 with iPrPNHP followed by the addition of NaHBEt3, however, forms a homogeneous catalyst favoring secondary aldimines for both hydrogenation and hydrogenative coupling of benzonitrile.
- Dai, Huiguang,Guan, Hairong
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p. 9125 - 9130
(2018/09/21)
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- Boron-Catalyzed Silylative Reduction of Nitriles in Accessing Primary Amines and Imines
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Silylative reduction of nitriles was studied under transition metal-free conditions by using B(C6F5)3 as a catalyst with hydrosilanes as a reductant. Alkyl and (hetero)aryl nitriles were efficiently converted to primary amines or imines under mild conditions. The choice of silanes was found to determine the selectivity: while a full reduction of nitriles was highly facile, the use of sterically bulky silanes allowed for the partial reduction leading to N-silylimines.
- Gandhamsetty, Narasimhulu,Jeong, Jinseong,Park, Juhyeon,Park, Sehoon,Chang, Sukbok
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p. 7281 - 7287
(2015/07/28)
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- NOVEL N-BENZYLAMIDE SUBSTITUTED DERIVATIVES OF 2-(ACYLAMIDO)ACETIC ACID AND 2-(ACYLAMIDO)PROPIONIC ACIDS: POTENT NEUROLOGICAL AGENTS
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A first aspect of the invention is a compound (sometimes also referred to herein as an "active agent" or "active compound") of Formula (I) or ( Ia): or a pharmaceutically acceptable salt or prodrug thereof. Compositions thereof and methods of using the same (e.g. for the treatment of a neurological disease) are also described.
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- Lacosamide isothiocyanate-based agents: Novel agents to target and identify lacosamide receptors
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(R)-Lacosamide ((R)-2, (R)-N-benzyl 2-acetamido-3-methoxypropionamide) has recently gained regulatory approval for the treatment of partial-onset seizures in adults.Whole animal pharmacological studies have documented that (R)-2 function is unique. A robust strategy is advanced for the discovery of interacting proteins associated with function and toxicity of (R)-2 through the use of (R)-2 analogues, 3, which contain "affinity bait (AB)" and "chemical reporter (CR)" functional groups. In 3, covalent modification of the interacting proteins proceeds at the AB moiety, and detection or isolation of the selectively captured protein occurs through the bioorthogonal CR group upon reaction with an appropriate probe. We report the synthesis, pharmacological evaluation, and interrogation of the mouse soluble brain proteome using 3 where the AB group is an isothiocyanate moiety. One compound, (R)-N-(4-isothiocyanato)benzyl 2-acetamido-3-(prop-2-ynyloxy) propionamide ((R)-9), exhibited excellent seizure protection in mice, and like (R)-2, anticonvulsant activity principally resided in the (R)-stereoisomer. Several proteins were preferentially labeled by (R)-9 compared with (S)-9, including collapsin response mediator protein 2. 2009 American Chemical Society.
- Ki, Duk Park,Morieux, Pierre,Salomé, Christophe,Cotten, Steven W.,Reamtong, Onrapak,Eyers, Claire,Gaskell, Simon J.,Stables, James P.,Liu, Rihe,Kohn, Harold
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supporting information; experimental part
p. 6897 - 6911
(2010/04/24)
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- Design, synthesis, and evaluation of isoindolinone-hydroxamic acid derivatives as histone deacetylase (HDAC) inhibitors
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We designed and synthesized hydroxamic acid derivatives bearing a 4-(3-pyridyl)phenyl group as a cap structure, and found that they exhibit potent histone deacetylase (HDAC) inhibitory activity. A representative compound, 17a, showed more potent growth-in
- Lee, Shoukou,Shinji, Chihiro,Ogura, Kiyoshi,Shimizu, Motomu,Maeda, Satoko,Sato, Mayumi,Yoshida, Minoru,Hashimoto, Yuichi,Miyachi, Hiroyuki
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p. 4895 - 4900
(2008/02/11)
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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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