- Mimicking transition metals in borrowing hydrogen from alcohols
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Borrowing hydrogen from alcohols, storing it on a catalyst and subsequent transfer of the hydrogen from the catalyst to anin situgenerated imine is the hallmark of a transition metal mediated catalyticN-alkylation of amines. However, such a borrowing hydrogen mechanism with a transition metal free catalytic system which stores hydrogen molecules in the catalyst backbone is yet to be established. Herein, we demonstrate that a phenalenyl ligand can imitate the role of transition metals in storing and transferring hydrogen molecules leading to borrowing hydrogen mediated alkylation of anilines by alcohols including a wide range of substrate scope. A close inspection of the mechanistic pathway by characterizing several intermediates through various spectroscopic techniques, deuterium labelling experiments, and DFT study concluded that the phenalenyl radical based backbone sequentially adds H+, H˙ and an electron through a dearomatization process which are subsequently used as reducing equivalents to the C-N double bond in a catalytic fashion.
- Banik, Ananya,Ahmed, Jasimuddin,Sil, Swagata,Mandal, Swadhin K.
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p. 8353 - 8361
(2021/07/02)
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- Pyridine mediated transition-metal-free direct alkylation of anilines using alcohols: via borrowing hydrogen conditions
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Herein, we report pyridine and other similar azaaromatics as efficient biomimetic hydrogen shuttles for a transition-metal-free direct N-alkylation of aryl and heteroaryl amines using a variety of benzylic and straight chain alcohols. Mechanistic studies including deuterium labeling and the isolation of dihydro-intermediates of the benzannulated pyridine confirmed the role of pyridine and a borrowing hydrogen process operating in these reactions. In addition, we have extended this methodology for the development of dehydrogenative synthesis of quinolines and indoles, as well as the transfer hydrogenation of ketones. This journal is
- Pothikumar, Rajagopal,Bhat, Venugopal T,Namitharan, Kayambu
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supporting information
p. 13607 - 13610
(2020/11/17)
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- Zinc-Catalyzed N-Alkylation of Aromatic Amines with Alcohols: A Ligand-Free Approach
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An efficient zinc-catalyzed N-alkylation reaction of aromatic amines was achieved using aliphatic, aromatic, and heteroaromatic alcohols as the alkylating reagent. A variety of aniline derivatives, including heteroaromatic amines, underwent the N-alkylation reaction and furnished the corresponding monoalkylated products in good to excellent yields. The application of the reaction is also further demonstrated by the synthesis of a 2-phenylquinoline derivative from acetophenone and 2-aminobenzyl alcohol. Deuterium labeling experiments show that the reaction proceeds via a borrowing hydrogen process. (Figure presented.).
- Sankar, Velayudham,Kathiresan, Murugavel,Sivakumar, Bitragunta,Mannathan, Subramaniyan
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supporting information
p. 4409 - 4414
(2020/09/01)
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- A nanoscale iron catalyst for heterogeneous direct: N - And C -alkylations of anilines and ketones using alcohols under hydrogen autotransfer conditions
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Here, we report a commercially available nanoscale Fe catalyst for heterogeneous direct N- and C-alkylation reactions of anilines and methyl ketones with alcohols. A hydrogen autotransfer mechanism has been found to operate in these reactions by deuterium labelling studies. In addition, dehydrogenative quinoline synthesis has been demonstrated from amino benzyl alcohols and acetophenones.
- Nallagangula, Madhu,Sujatha, Chandragiri,Bhat, Venugopal T.,Namitharan, Kayambu
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supporting information
p. 8490 - 8493
(2019/07/22)
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- Selective Monoarylation of Primary Amines Using the Pd-PEPPSI-IPentCl Precatalyst
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A single set of reaction conditions for the palladium-catalyzed amination of a wide variety of (hetero)aryl halides using primary alkyl amines has been developed. By combining the exceptionally high reactivity of the Pd-PEPPSI-IPentCl catalyst (PEPPSI=pyridine enhanced precatalyst preparation, stabilization, and initiation) with the soluble and nonaggressive sodium salt of BHT (BHT=2,6-di-tert-butyl-hydroxytoluene), both six- and five-membered (hetero)aryl halides undergo efficient and selective amination.
- Sharif, Sepideh,Rucker, Richard P.,Chandrasoma, Nalin,Mitchell, David,Rodriguez, Michael J.,Froese, Robert D. J.,Organ, Michael G.
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supporting information
p. 9507 - 9511
(2015/08/11)
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- Insight into O2-promoted base-catalyzed N-alkylation of amines with alcohols
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A highly efficient and practical transition-metal-free CsOH/O2 catalyst system was developed for the N-alkylation of amines with alcohols under argon. This strategy was compatible with many alcohols and exhibits excellent functional group tolerance. More significantly, the selective formation of secondary amines was achieved in excellent yields. The detailed mechanistic study gave a clear understanding of the role of base and oxygen in the catalytic cycle.
- Wang, Chao,Chen, Changpeng,Han, Jian,Zhang, Jingyu,Yao, Yingming,Zhao, Yingsheng
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supporting information
p. 2972 - 2977
(2015/04/27)
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- Structure-dependent tautomerization induced catalyst-free autocatalyzed N-alkylation of heteroaryl amines with alcohols
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Catalyst-free autocatalyzed dehydrative N-alkylation reactions of 2-aminobenzothiazoles, 2-aminopyrimidines, and 2-aminopyrazine with primary and secondary alcohols have been achieved for efficient, practical, and green synthesis of the versatile heteroaryl amine derivatives. These reactions were interestingly induced by structure-dependent tautomeric equilibria of the heteroaryl amines via MPV-O transfer hydrogenation of the imino tautomers by alcohols to give aldehydes as the key initiating step.
- Li, Shuangyan,Li, Xiaohui,Li, Qiang,Yuan, Qiaochao,Shi, Xinkang,Xu, Qing
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supporting information
p. 3260 - 3265
(2015/06/25)
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- Towards aryl C-N bond formation in dynamic thin films
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C-N bond forming reactions are important in organic chemistry. A thin film microfluidic vortex fluidic device (VFD) operating under confined mode affords N-aryl compounds from 2-chloropyrazine and the corresponding amine, without the need for a transition
- Gandy, Michael N.,Raston, Colin L.,Stubbs, Keith A.
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supporting information
p. 4594 - 4597
(2014/06/24)
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- Sodium hydroxide catalyzed N-alkylation of (hetero) aromatic primary amines and N1,C5-dialkylation of 4-phenyl-2-aminothiazoles with benzyl alcohols
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In the presence of a catalytic amount of NaOH, the selective N-alkylation of various heteroaromatic primary amines is reported. With 1 equiv of NaOH, N1,C5-dialkylation of 4-phenyl-2-aminothiazoles has been investigated. Reaction of in situ generated aldehyde with amine yields the N-alkylated and N1,C5-dialkylated products through hydride ion transformation from alcohol.
- Donthiri, Ramachandra Reddy,Pappula, Venkatanarayana,Chandra Mohan, Darapaneni,Gaywala, Hiren H.,Adimurthy, Subbarayappa
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p. 6775 - 6781
(2013/07/26)
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- Buchwald-Hartwig amination of (hetero)aryl chlorides by employing Mor-DalPhos under aqueous and solvent-free conditions
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We report on the application of the [Pd(cinnamyl)Cl]2/Mor- DalPhos catalyst system in the Buchwald-Hartwig amination of (hetero)aryl chlorides with primary or secondary amines conducted either under aqueous conditions without the use of co-solvents and/or surfactants or under solvent-free conditions (52 examples). We have established that reactions of this type can be conducted without the rigorous exclusion of air, and in the case of the solvent-free reactions, we have demonstrated that appropriately selected liquid and solid reagents can be employed successfully.
- Tardiff, Bennett J.,Stradiotto, Mark
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experimental part
p. 3972 - 3977
(2012/08/27)
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- Heteroaromatic-aminomethyl quinolones: Potent and selective iNOS inhibitors
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The overproduction of nitric oxide during the biological response to inflammation by the nitric oxide synthase (NOS) enzymes have been implicated in the pathology of many diseases. By removal of the amide core from uHTS-derived quinolone 4, a new series highly potent heteroaromatic-aminomethyl quinolone iNOS inhibitors 8 were identified. SAR studies led to identification of piperazine 22 and pyrimidine 32, both of which reduced plasma nitrates following oral dosing in a mouse lipopolysaccharide challenge assay.
- Duron, Sergio G.,Lindstrom, Andrew,Bonnefous, Celine,Zhang, Hui,Chen, Xiaohong,Symons, Kent T.,Sablad, Marciano,Rozenkrants, Natasha,Zhang, Yan,Wang, Li,Yazdani, Nahid,Shiau, Andrew K.,Noble, Stewart A.,Rix, Peter,Rao, Tadimeti S.,Hassig, Christian A.,Smith, Nicholas D.
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scheme or table
p. 1237 - 1241
(2012/03/11)
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- N-(alkyl)-2-amino-1,4-pyrazine derivatives: Synthesis and antioxidative properties of 3- and 3,5-p-hydroxyphenyl-substituted compounds
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2-Amino-5-(p-hydroxyphenyl)-1,4-pyrazine and 2-amino-3,5-bis(p-hydroxyphenyl)-1,4-pyrazine are endowed with excellent antioxidative properties. For a possible development in medicinal chemistry, the lipophilicity of these lead compounds has to be increased. Therefore various methods of N-alkylation were systematically explored. The best results were obtained by quenching aminopyrazinyl anion with alkyl iodides, and by coupling aldehydes (reductive amination) in the presence of phenylsilane and tin catalyst. Aminopyrazines equipped with linear alkyl side-chains of at least six carbons showed improved radical-scavenging properties in lipidic media.
- Jeanjot, Paul,Bruyneel, Fre?de?ric,Arrault, Axelle,Gharbi, Sonia,Cavalier, Jean-Franc?ois,Abels, Agne?s,Marchand, Ce?cile,Touillaux, Roland,Rees, Jean-Franc?ois,Marchand-Brynaert, Jacqueline
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p. 513 - 522
(2007/10/03)
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- Pyridinium N-,(2'-azinyl)aminides: Regioselective synthesis of 2- alkylaminoazines
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The regioselective alkylation of pyridinium-N-(2f'-azinil)aminides with alkyl halides under mild conditions is described. The alkylation, combined with a reduction of the N-N bond, allows an easy preparation of 2- alkylaminoazines. (C) 2000 Elsevier Science Ltd.
- Martínez-Barrasa, Valentín,Delgado, Francisca,Burgos, Carolina,Luis García-Navío,Luisa Izquierdo,Alvarez-Builla, Julio
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p. 2481 - 2490
(2007/10/03)
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- Second-generation peptidomimetic inhibitors of protein farnesyltransferase demonstrating improved cellular potency and significant in vivo efficacy
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The synthesis and evaluation of analogues of previously reported farnesyltransferase inhibitors, pyridyl benzyl ether 3 and pyridylbenzylamine 4, are described. Substitution of 3 at the 5-position of the core awl ring resulted in inhibitors of equator less potency against the enzyme and decreased efficacy in a cellular assay against Ras processing by the enzyme. Substitution of 4 at the benzyl nitrogen yielded 26, which showed improved efficacy and potency and yet presented a poor pharmacokinetic profile. Further modification afforded 30, which demonstrated a dramatically improved pharmacokinetic profile. Compounds 26 and 29 demonstrated significant in vivo efficacy in nude mice inoculated with MiaPaCa-2, a human pancreatic tumor- derived cell line.
- O'Connor, Stephen J.,Barr, Kenneth J.,Wang, Le,Sorensen, Bryan K.,Tasker, Andrew S.,Sham, Hing,Shi-Chung, Ng,Cohen, Jerome,Devine, Edward,Cherian, Sajeev,Saeed, Badr,Zhang, Haichao,Jang Yun, Lee,Warner, Robert,Tahir, Stephen,Kovar, Peter,Ewing, Patricia,Alder, Jeffrey,Mitten, Michael,Leal, Juan,Marsh, Kennan,Bauch, Joy,Hoffman, Daniel J.,Sebti, Said M.,Rosenberg, Saul H.
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p. 3701 - 3710
(2007/10/03)
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