- Discovery of competing anaerobic and aerobic pathways in umpolung amide synthesis allows for site-selective amide18O-labeling
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The mechanism of umpolung amide synthesis was probed by interrogating potential sources for the oxygen of the product amide carbonyl that emanates from the α-bromo nitroalkane substrate. Using a series of 18O-labeled substrates and reagents, evidence is gathered to advance two pathways from the putative tetrahedral intermediate. Under anaerobic conditions, a nitro-nitrite isomerization delivers the amide oxygen from nitro oxygen. The same homolytic nitro-carbon fragmentation can be diverted by capture of the carbon radical intermediate with oxygen gas (O2) to deliver the amide oxygen from O2. This understanding was used to develop a straightforward protocol for the preparation of 18O-labeled amides in peptides by simply performing the umpolung amide synthesis reaction under an atmosphere of 18O2.
- Shackleford, Jessica P.,Shen, Bo,Johnston, Jeffrey N.
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- Preparation of polymer-bound pyrazolone active esters for combinatorial chemistry
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The preparation of solid-phase active esters from a new pyrazolone linker resin is described. N-Acylation using this resin provides various amide products with a high conversion rate and good purity under mild conditions. The polymer-bound pyrazolone linkers are stable in the reaction conditions and are resistant to hydrolysis. Moreover, this resin can also be reused repeatedly without a loss of reactivity.
- Byun, Jang-Woong,Lee, Dong-Hoon,Lee, Yoon-Sik
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- Reactions of acyl nitroso compounds with amines: Production of nitroxyl (HNO) with the preparation of amides
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Oxidation of hydroxamic acids in the presence of amines generates nitrous oxide (N2O) and the corresponding amide. The identification of N2O suggests the intermediacy of nitroxyl (HNO). Retro-Diels Alder dissociation of cyclopentadiene-acyl nitroso compound cycloadducts releases N2O with amide formation.
- Atkinson, Robert N.,Storey, Bernadette M.,King, S. Bruce
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- Amino-functionalized carbon nanotubes as nucleophilic scavengers in solution phase combinatorial synthesis
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A versatile method for fast scavenging a variety of electrophiles using carbon nanotubes functionalized by amino groups (CNT-NH2) is reported. Following the scavenging event, CNT-NH2 can be easily separated from the reaction mixture by filtration, leaving the desired products in excellent yields and purities.
- Li, Yongsheng,Zhao, Yuzeng,Zhang, Zhuo,Xu, Yaomin
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- Sulfated tungstate: A new solid heterogeneous catalyst for amide synthesis
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Amide formation avoiding poor atom economy reagents is a priority area. We have synthesized sulfated tungstate as a new reusable and environmentally benign heterogeneous catalyst for direct amide formation between carboxylic acid and amine. It has potential for large scale applications.
- Chaudhari, Pramod S.,Salim, Suresh D.,Sawant, Ravindra V.,Akamanchi, Krishnacharya G.
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- Synthesis of some α-ketophosphonates comprising mobile hydrogens in position α: Spectroscopic characteristics of 1H, 13C, 31P NMR and IR reactivities among amines and hydrazine derivatives
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In the present work we describe the keto-enol equilibrium of some acylphosphonates 1 by means of 1H, 13C, 31P NMR, and IR data which show that the enol form has E configuration. The keto/enol ratio is determined on the basis of 31P NMR data. The reactivity of 1 with hydrazines derivatives and primary amines are reported. The structure of all compounds is determined by 1H, 13C, 31P NMR, and IR.
- Hassen, Zied,Akacha, Azaiez Ben,Zantour, Hedi
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- Oxidative amide synthesis and N-terminal α-amino group ligation of peptides in aqueous medium
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A new method for oxidative synthesis of amides from alkynes and amines in high yields (up to 96%) using [Mn(2,6-Cl2TPP)Cl] 1 as a catalyst and Oxone/H2O2 as an oxidant in aqueous medium has been developed. This method could be used for N-terminal α-amino group ligation of unprotected peptides with aryl, aliphatic, and internal alkynes under mild conditions. Copyright
- Chan, Wing-Kei,Ho, Chi-Ming,Wong, Man-Kin,Che, Chi-Ming
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Read Online
- Photoinduced Carbamoylation of C(sp3)H Bonds with Isocyanates
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Alkylbenzenes coupled with isocyanates at the benzylic position upon irradiation with visible light in the presence of an iridium photoredox catalyst, a bromide anion, and a nickel catalyst, producing N-substituted α-aryl amides. An analogous carbamoylation reaction of aliphatic CH bonds of alkanes took place when UV light and a diaryl ketone were used instead of visible light and the iridium complex. The present reaction offers a straightforward and atom-economical method for the synthesis of carboxamides starting from hydrocarbons with one-carbon extension.
- Ishida, Naoki,Kawasaki, Tairin,Murakami, Masahiro,Tomono, Ryota,Yamazaki, Katsushi
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supporting information
p. 1684 - 1684
(2021/09/16)
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- Metal-free Photocatalytic Intermolecular anti-Markovnikov Hydroamination of Unactivated Alkenes
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The development of photocatalytic intermolecular hydroamination reaction between N-aminated dihydropyridines and unactivated alkenes is reported. Metal-free co-catalysts, rhodamine 6G and thiophenol, in presence of visible light are used to initiate the process. The transformation shows a broad substrate scope, both alkenes and amidyl radical can act as coupling partners. The radical strategy provides excellent anti-Markovnikov selectivity and regioselectivity in diene substrates.
- Li, Juncheng,Wang, Ting,Zhao, Gaoyuan
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supporting information
p. 2650 - 2654
(2021/06/25)
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- Copper(II)-Photocatalyzed N-H Alkylation with Alkanes
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We report a practical method for the alkylation of N-H bonds with alkanes using a photoinduced copper(II) peroxide catalytic system. Upon light irradiation, the peroxide serves as a hydrogen atom transfer reagent to activate stable C(sp3)-H bonds for the reaction with a broad range of nitrogen nucleophiles. The method enables the chemoselective alkylation of amides and is utilized for the late-stage functionalization of N-H bond containing pharmaceuticals with good to excellent yields. The mechanism of the reaction was preliminarily investigated by radical trapping experiments and spectroscopic methods.
- Donabauer, Karsten,K?nig, Burkhard,Narobe, Rok,Yakubov, Shahboz,Zheng, Yi-Wen
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p. 8582 - 8589
(2020/09/23)
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- Direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2
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This paper described a mild and efficient direct amidation of non-activated carboxylic acid and amine derivatives catalyzed by TiCp2Cl2. Arylacetic acid derivatives reacted with different amines to afford the corresponding amides in good to excellent yield except of aniline. Aryl formic acids failed to react with aniline but smoothly reacted with aliphatic amines and benzylamine in moderate to good yield, fatty acids reacting with benzyl and aliphatic amines give amides in good to excellent yield. Chiral amino acids derivatives were transformed into amides without racemization in moderate yield. The possible mechanism of direct amidation catalyzed by TiCp2Cl2 was discussed. This catalytic method is very suitable for the amidation of low sterically hindered arylacetic acid, fatty acids with different low sterically hindered amines except aniline, as well as the amidation of aryl formic acid with benzyl and aliphatic amines.
- Wang, Hui,Dong, Wei,Hou, Zhipeng,Cheng, Lidan,Li, Xiufen,Huang, Longjiang
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- Solvent-Free N-Alkylation of Amides with Alcohols Catalyzed by Nickel on Silica–Alumina
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The N-alkylation of phenylacetamide with benzyl alcohol has been studied using Ni/SiO2–Al2O3. In the optimized conditions, the desired product was isolated in an excellent 98 % yield. The reaction could advantageously be performed in neat conditions, with a slight excess of amide and a catalytic amount of base. These conditions were tested on a large range of amides and alcohols, affording 24 compounds in 13 to 99 % isolated yields.
- Charvieux, Aubin,Le Moigne, Louis,Borrego, Lorenzo G.,Duguet, Nicolas,Métay, Estelle
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supporting information
p. 6842 - 6846
(2019/11/11)
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- Palladium-catalyzed carbonylation of benzylic ammonium salts to amides and esters: Via C-N bond activation
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An efficient palladium-catalyzed carbonylation reaction of readily available quaternary ammonium salts with CO is reported for the first time to afford arylacetamides and arylacetic acid esters via benzylic C-N bond cleavage. This protocol features mild reaction conditions under atmospheric pressure of CO, a redox-neutral process without an additional oxidant, and a broad substrate scope for various kinds of amines, alcohols and phenols.
- Yu, Weijie,Yang, Shuwu,Xiong, Fei,Fan, Tianxiang,Feng, Yan,Huang, Yuanyuan,Fu, Junkai,Wang, Tao
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p. 3099 - 3103
(2018/05/22)
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- Novel green acylamide synthesis method through quaternary ammonium salt C-N bond fracture
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The invention provides a novel green acylamide synthesis method through quaternary ammonium salt C-N bond fracture. The structure of the compound is expressed by methods such as H NMR, C, NMR and HRMS and is confirmed. A series of phenmethyl quaternary ammonium salts and aminated compounds are used; under the catalysis effect of PdCl2(dppf), PPh3 is used as a ligand, Na2CO3 is used as the alkali, and corresponding amide compounds are generated in the 100-DEG C CO atmosphere in a pHMe/DMSO mixed solvent. The method has the advantages that the efficiency is high; the toxicity is low; the conditions are mild; the application range of the substrate is wide; the yield is high; the product purity is high; the separation is convenient; the method can be applicable to large-scale preparation; the application prospects are wide.
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Paragraph 0064-0066
(2017/04/19)
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- Nickel-Catalyzed Reductive Addition of Aryl/Benzyl Halides and Pseudohalides to Carbodiimides for the Synthesis of Amides
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A Nickel-catalyzed reductive process is described for the direct amidation of benzyl and aryl halides using carbodiimides as the amidating agent. Moreover, aryl and benzyl C–O electrophiles such as triflate, acetate, tosylate, trityl ether, and pivalate were converted into amides using this method. The in-situ-generated Ni0acts as a catalyst for the reaction at room temperature for benzylic substrates, and 70 °C for aryl electrophiles. This new nickel-catalyzed reductive coupling protocol provides a general and operationally simple method for the synthesis of diverse amides using carbodiimides. Amides bearing bulky substituents can be synthesized by this strategy in high yield, which demonstrates its effectiveness in amide synthesis.
- Panahi, Farhad,Jamedi, Fereshteh,Iranpoor, Nasser
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p. 780 - 788
(2017/01/18)
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- Sterically Demanding Oxidative Amidation of α-Substituted Malononitriles with Amines Using O2
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An efficient amidation method between readily available 1,1-dicyanoalkanes and either chiral or nonchiral amines was realized simply with molecular oxygen and a carbonate base. This oxidative protocol can be applied to both sterically and electronically challenging substrates in a highly chemoselective, practical, and rapid manner. The use of cyclopropyl and thioether substrates support the radical formation of α-peroxy malononitrile species, which can cyclize to dioxiranes that can monooxygenate malononitrile α-carbanions to afford activated acyl cyanides capable of reacting with amine nucleophiles.
- Li, Jing,Lear, Martin J.,Hayashi, Yujiro
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supporting information
p. 9060 - 9064
(2016/07/26)
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- An attractive route to transamidation catalysis: Facile synthesis of new o-aryloxide-N-heterocyclic carbene ruthenium(II) complexes containing trans triphenylphosphine donors
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Well-defined robust ruthenium(II) complexes 3a-d bearing o-aryloxide-N-heterocyclic carbene ligands with different wingtip substituents (3a (R = Me), 3b (R = Ph), 3c (R = iPr) and 3d (R = Mes)) in the imidazole ring were synthesized in good yields by the reaction of imidazolium proligands with metal precursor [RuHCl(CO)(PPh3)3] by transmetallation from the corresponding silver carbene complexes. All the Ru(II)-NHC complexes have been characterized by elemental analyses, spectroscopic methods as well as ESI mass spectrometry. The molecular structure of the complex 3a was identified by means of single-crystal X-ray diffraction analysis, which revealed that the complexes possess a distorted octahedral geometry. In order to explore the catalytic potential of the synthesized complexes, all the four [Ru-NHC] complexes [3a-d] were tested as catalysts for transamidation of carboxamides with amines. Notably, the complex 3a was found to be very efficient and versatile catalyst toward transamidation of a wide range of amides with amines.
- Nirmala, Muthukumaran,Prakash, Govindan,Viswanathamurthi, Periasamy,Malecki, Jan Grzegorz
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- Ammonium nitrate: A biodegradable and efficient catalyst for the direct amidation of esters under solvent-free conditions
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A simple, metal-free, and environment-friendly procedure is developed for the direct conversion of esters to amides using ammonium nitrate as a catalyst under solvent-free conditions. Aryls, heteroaryls, and aliphatic esters are easily converted to the corresponding amides in excellent isolated yields (85-99%). An enantiopure ester and amine were both shown to react without racemization. The methodology has been successfully applied to preparation of procainamide.
- Ramesh, Perla,Fadnavis, Nitin W.
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supporting information
p. 138 - 140
(2015/02/19)
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- Hafnium-catalyzed direct amide formation at room temperature
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Herein, the first example of a metal-catalyzed protocol for direct amidation of nonactivated carboxylic acids at ambient temperature (26 °C) is presented. The mild reaction conditions give rise to high yields of a range of amides in reaction times as short as 90 min, employing a commercial hafnium complex, [Hf(Cp)2Cl2], as catalyst. Amino acids are transformed into their corresponding amides without racemization, and the catalyst displays full selectivity for the amidation of carboxylic acids over esters. Electronic properties of the carboxylic acids were found to have a strong influence on the rate of the amidation reaction, and the need for a balanced amount of molecular sieves was observed to be highly important for optimal reaction outcome.
- Lundberg, Helena,Adolfsson, Hans
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p. 3271 - 3277
(2015/06/16)
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- Metal-free carbon-carbon cross-couplings between the ion pairs in sulfonium tetraphenylborates
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A series of sulfonium tetraphenylborates can be readily prepared by the metathesis of sulfonium halides with sodium tetraphenylborates. After heating at 120-150 °C, the sulfonium tetraphenylborates can smoothly undergo the cross-couplings between the tetraphenylborate anions and the sulfonium cations in the absence of a metal catalyst. For carbonylmethyl-, benzyl-, and allylsulfoniums, the corresponding carbonylmethyl-phenyl, benzyl-phenyl, and allyl-phenyl cross-coupling products can be obtained in 22-76% yields. An interionic electron-transfer mechanism for this cross-coupling reaction is proposed.
- Xu, Mei-Li,Huang, Wenhua
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p. 4230 - 4232
(2014/07/22)
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- Photoinduced, copper-catalyzed alkylation of amides with unactivated secondary alkyl halides at room temperature
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The development of a mild and general method for the alkylation of amides with relatively unreactive alkyl halides (i.e., poor substrates for S N2 reactions) is an ongoing challenge in organic synthesis. We describe herein a versatile transition-metal-catalyzed approach: in particular, a photoinduced, copper-catalyzed monoalkylation of primary amides. A broad array of alkyl and aryl amides (as well as a lactam and a 2-oxazolidinone) couple with unactivated secondary (and hindered primary) alkyl bromides and iodides using a single set of comparatively simple and mild conditions: inexpensive CuI as the catalyst, no separate added ligand, and C-N bond formation at room temperature. The method is compatible with a variety of functional groups, such as an olefin, a carbamate, a thiophene, and a pyridine, and it has been applied to the synthesis of an opioid receptor antagonist. A range of mechanistic observations, including reactivity and stereochemical studies, are consistent with a coupling pathway that includes photoexcitation of a copper-amidate complex, followed by electron transfer to form an alkyl radical.
- Do, Hien-Quang,Bachman, Shoshana,Bissember, Alex C.,Peters, Jonas C.,Fu, Gregory C.
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supporting information
p. 2162 - 2167
(2014/03/21)
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- Umpolung Amide Synthesis using substoichiometric N-iodosuccinimide (NIS) and oxygen AS a terminal oxidant
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Umpolung Amide Synthesis (UmAS) provides direct access to amides from an α-bromo nitroalkane and an amine. Based on its mechanistic bifurcation after convergent C-N bond formation, depending on the absence or presence of oxygen, UmAS using substoichiometric N-iodosuccinimide (NIS) under aerobic conditions has been developed. In combination with the enantioselective preparation of α-bromo nitroalkane donors, this protocol realizes the goal of enantioselective α-amino amide and peptide synthesis based solely on catalytic methods.
- Schwieter, Kenneth E.,Shen, Bo,Shackleford, Jessica P.,Leighty, Matthew W.,Johnston, Jeffrey N.
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supporting information
p. 4714 - 4717
(2015/04/27)
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- Palladium-catalyzed oxidative aminocarbonylation: A new entry to amides via C-H activation
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A novel palladium-catalyzed oxidative aminocarbonylation reaction via C(sp3)-H activation was established, which provides a convenient and general method for the construction of arylacetamides via the carbonylation reaction of alkyl aromatics and amines. By using this protocol, the marketed drug ibuprofen could be easily obtained.
- Xie, Pan,Xia, Chungu,Huang, Hanmin
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supporting information
p. 3370 - 3373
(2013/07/26)
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- An efficient protocol for the preparation of amides by copper-catalyzed reactions between nitriles and amines in water
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The reactions between nitriles and amines catalyzed by Cu(OAc)2 and 2-piperidinecarboxylic acid were carried out in pure water without any other additives. A variety of substituted amides can be obtained in moderate to good yields up to 90%.
- Li, Xiaoya,Li, Zhengkai,Deng, Hang,Zhou, Xiangge
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supporting information
p. 2212 - 2216
(2013/05/09)
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- Sulfated tungstate: A highly efficient catalyst for transamidation of carboxamides with amines
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An environmentally benign protocol for the transamidation of carboxamides with amines using sulfated tungstate, as a heterogeneous catalyst, has been developed. The method has been successfully applied to the synthesis of a wide range of aromatic and aliphatic amides and phthalimides. Efficient transformation, mild reaction conditions, easy product isolation and the potential reusability of the catalyst are attractive features.
- Pathare, Sagar P.,Jain, Ashish Kumar H.,Akamanchi, Krishnacharya G.
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p. 7697 - 7703
(2013/06/27)
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- Dehydrogenative amide synthesis: Azide as a nitrogen source
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A new atom-economical strategy to amide linkage from an azide and alcohol liberating hydrogen and nitrogen was developed with an in situ generated ruthenium catalytic system. The reaction has broad substrate generality including diols for the synthesis of cyclic imides.
- Fu, Zhenqian,Lee, Jeongbin,Kang, Byungjoon,Hong, Soon Hyeok
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supporting information
p. 6028 - 6031
(2013/02/22)
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- Efficient copper(II)-catalyzed transamidation of non-activated primary carboxamides and ureas with amines
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Amid(e) them all: Primary carboxamides and ureas react with aromatic and aliphatic amines in the presence of a copper catalyst to give a wide range of functionalized amides (see scheme). Copyright
- Zhang, Min,Imm, Sebastian,Baehn, Sebastian,Neubert, Lorenz,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 3905 - 3909
(2012/06/04)
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- Direct use of dioxygen as an oxygen source: Catalytic oxidative synthesis of amides
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The first transition-metal-catalyzed direct oxidative synthesis of amides by using dioxygen as an oxygen source has been developed under mild conditions, in which DBU was used as the key additive. The present methodology, which utilizes dioxygen as an oxidant and oxygen source and cheap copper salts as catalysts, opens up an interesting and attractive avenue for the synthesis of amide functionality.
- Wei, Wei,Hu, Xiao-Yu,Yan, Xiao-Wei,Zhang, Qiang,Cheng, Ming,Ji, Jian-Xin
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supporting information; experimental part
p. 305 - 307
(2012/01/06)
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- Practical synthesis of amides from alkynyl bromides, amines, and water
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A general and efficient method for the synthesis of a wide range of amides is described here. The reactions were conducted under convenient conditions and provided secondary and tertiary amides in moderate to excellent yields. A variety of amines and substituted alkynyl bromides were used to investigate the scope of the reactions.
- Chen, Zheng-Wang,Jiang, Huan-Feng,Pan, Xiao-Yan,He, Zai-Jun
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experimental part
p. 5920 - 5927
(2011/09/19)
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- Umpolung reactivity in amide and peptide synthesis
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The amide bond is one of natureg€s most common functional and structural elements, as the backbones of all natural peptides and proteins are composed of amide bonds. Amides are also present in many therapeutic small molecules. The construction of amide bonds using available methods relies principally on dehydrative approaches, although oxidative and radical-based methods are representative alternatives. In nearly every example, carbon and nitrogen bear electrophilic and nucleophilic character, respectively, during the carbong€"nitrogen bond-forming step. Here we show that activation of amines and nitroalkanes with an electrophilic iodine source can lead directly to amide products. Preliminary observations support a mechanism in which the polarities of the two reactants are reversed (German, umpolung) during carbong€"nitrogen bond formation relative to traditional approaches. The use of nitroalkanes as acyl anion equivalents provides a conceptually innovative approach to amide and peptide synthesis, and one that might ultimately provide for efficient peptide synthesis that is fully reliant on enantioselective methods.
- Shen, Bo,Makley, Dawn M.,Johnston, Jeffrey N.
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experimental part
p. 1027 - 1032
(2011/08/06)
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- Synthesis of an acyltrifluoroborate and its fusion with azides to form amides
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A uniquely stable acyl potassium trifluoroborate, potassium (2-phenylacetyl)trifluoroborate, has been synthesized and isolated. In the presence of an activating Lewis acid, this reagent reacts with azides to form amides in good yields.
- Molander, Gary A.,Raushel, Jessica,Ellis, Noel M.
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supporting information; experimental part
p. 4304 - 4306
(2010/09/04)
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- A convenient aminolysis of esters catalyzed by 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) under solvent-free conditions
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Aminolysis of esters by using the organocatalyst 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) is reported. Secondary and tertiary amides were synthesized from alkyl or aryl esters with a variety of primary and secondary amines in good to excellent yields (60-94%) under solvent-free conditions (SFC).
- Sabot, Cyrille,Kumar, Kanduluru Ananda,Meunier, Stéphane,Mioskowski, Charles
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p. 3863 - 3866
(2008/02/02)
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- PS-IIDQ: a supported coupling reagent for efficient and general amide bond formation
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Polystyrene-IIDQ, a polymer-supported coupling reagent, was synthesized in three steps from Merrifield resin in 86% overall conversion. This reagent efficiently coupled carboxylic acids to amines in good yields and high purities, required no pre-activation step, and was tolerant of the order of reagent addition. PS-IIDQ was observed to be more efficient than polymer-supported carbodiimides (PS-EDC and PS-DCC) and gave higher yields than HATU for general amide bond formation, including the coupling of anilines and hindered substrates. When evaluated with five carboxylic acids and nine amines (including anilines and secondary amines) PS-IIDQ gave an average isolated yield of 73%.
- Valeur, Eric,Bradley, Mark
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p. 8855 - 8871
(2008/02/11)
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- Optimization of amide-based inhibitors of soluble epoxide hydrolase with improved water solubility
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Soluble epoxide hydrolase (sEH) plays an important role in the metabolism of endogenous chemical mediators involved in the regulation of blood pressure and inflammation. 1,3-Disubstituted ureas with a polar group located on the fifth atom from the carbonyl group of urea function are active inhibitors of sEH both in vitro and in vivo. However, their limited solubility in water and relatively high melting point lead to difficulties in formulating the compounds and poor in vivo efficacy. To improve these physical properties, the effect of structural modification of the urea pharmacophore on the inhibition potencies, water solubilities, octanol/water partition coefficients (log P), and melting points of a series of compounds was evaluated. For murine sEH, no loss of inhibition potency was observed when the urea pharmacophore was modified to an amide function, while for human sEH 2.5-fold decreased inhibition was obtained in the amide compounds. In addition, a NH group on the right side of carbonyl group of the amide pharmacophore substituted with an adamantyl group (such as compound 14) and a methylene carbon present between the adamantyl and amide groups were essential to produce potent inhibition of sEH. The resulting amide inhibitors have 10-30-fold better solubility and lower melting point than the corresponding urea compounds. These findings will facilitate synthesis of sEH inhibitors that are easier to formulate and more bioavailable.
- Kim, In-Hae,Heirtzler, Fenton R.,Morisseau, Christophe,Nishi, Kosuke,Tsai, Hsing-Ju,Hammock, Bruce D.
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p. 3621 - 3629
(2007/10/03)
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- Dephosphonylation of β-carbonyl phosphonates
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A new methodology has been developed for the P-C bond cleavage of β- carbonyl phosphonates. The α,α-disubstituted β-keto phosphonates and the α-carbamoyl phosphonates have been shown to undergo dephosphonylation by reaction of their lithium enolate with LiAlH4, followed by quenching with aqueous H2SO4, affording regioselectively α,α-disubstituted ketone and α-substituted and α,α-disubstituted secondary amides.
- Lee, Shi Yong,Lee, Chi-Wan,Oh, Dong Young
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p. 7017 - 7022
(2007/10/03)
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- Triethyl phosphite-p-dimethylaminopyridine, a new reagent for direct syntheses of amides from aliphatic carboxylic acids and amines
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Various amides have been prepared with high to moderate yields from the corresponding aliphatic carboxylic acids and amines using triethyl phosphite-p-dimethylaminopyridine as a new reagent and pyridine as solvent, at 100-110°C, for 12 hours.
- Chiriac, Constantin I.,Onciu, Marioara,Tǎnasǎ, Fulga,Bǎdǎrǎu, Cristina,Tru?can, Ion
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p. 971 - 974
(2007/10/03)
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- Direct synthesis of amides from carboxylic acids and amines with benzenesulfonyl chloride as reagent in aqueous medium
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Various amides have been prepared by a direct condensation reaction between carboxylic acids and amines in aqueous medium, using benzenesulfonyl chloride as reagent. The occurrence of this reaction in the presence of water is a proof that the mixt anhydrides, which result "in situ" as intermediary products, have a relative stability to hydrolysis and can react with amines affording amides in moderate yields. This reaction has a biological importance, because the synthesis of amidic bond in living organisms occurs also in the presence of water.
- Ropot, Radu,Tru?can, Ion,Chiriac, Constantin I.
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p. 153 - 155
(2007/10/03)
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- Flash photolytic generation of primary, secondary, and tertiary ynamines in aqueous solution and study of their carbon-protonation reactions in that medium
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A group of nine phenylynamines (PhC≡CNH2, PhC≡CNHCH(CH3)2, PhC≡CNHC6H11, PhC≡CNHC6H5, PhC≡CNHC6F5, PhC≡CN(CH2)5, PhC≡CN(CH2CH2)2O, PhC≡CN(CH2CH2CN)2, and PhC≡CN(CH3)C6F5) were generated in aqueous solution by flash photolytic decarbonylation of the corresponding phenylaminocyclopropenones, and the kinetics of their facile decay in that medium were studied. This decay is catalyzed by acids for all ynamines-primary, secondary, and tertiary-and also by bases for primary and secondary ynamines. Solvent isotope effects and the form of acid-base catalysis show that the acid-catalyzed path involves formation of keteniminium ions by rate-determining proton transfer to the β-carbon atoms of the ynamines. The ions generated from primary and secondary ynamines then lose nitrogen-bound protons to give ketenimines, and the ketenimines obtained from secondary ynamines are hydrated to phenylacetamides, whereas that from the primary ynamine tautomerizes to phenylacetonitrile. Keteniminium ions formed from tertiary ynamines have no nitrogen-bound protons that can be lost, and they are therefore captured by water instead, and the amide enols thus produced then ketonize to phenylacetamides. The base-catalyzed decay of primary and secondary ynamines also generates ketenimines, but protonation on the β-carbon is now preceeded by proton removal from nitrogen. Rate constants for β-carbon protonation of PhC≡CNHCH(CH3)2 and PhC≡CN(CH2)5 by a series of carboxylic acids give linear Bronsted relations with exponents α = 0.29 and 0.28, respectively, whereas inclusion of literature data for protonation of PhC≡CN-(CH2)5 by a group of weaker acids gives a curved Bronsted relation whose exponent varies from 0.25 to 0.97. Application of Marcus rate theory to this curved Bronsted relation produces the intrinsic barrier ΔG((+))(o) = 3.26 ± 0.19 kcal mol-1 and the work term w(r) = 8.11 ± 0.15 kcal mol-1.
- Chiang,Grant,Kresge,Paine
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p. 4366 - 4372
(2007/10/03)
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- 3-ACYL-2-(N-CYANOIMINO)THIAZOLIDINES AS AN ACYLATING AGENT. PREPARATION OF AMIDES, ESTERS, AND THIOESTERS
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3-Acyl-2-(N-cyanoimino)thiazolidines proved to be powerful acylating agents.They reacted easily with amines, alcohols and thiols to give the corresponding amides, esters and thioesters in good yields.
- Iwata, Chuzo,Watanabe, Mayumi,Okamoto, Shigeha,Fujimoto, Michitaro,Sakae, Masatoshi,et al.
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p. 323 - 326
(2007/10/02)
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- Monitored Aminolysis of 3-Acyl-1,3-thiazolidine-2-thiones: Synthesis of Amides and Amide Alkaloids
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A functional heterocycle, 3-acyl-1,3-thiazolidine-2-thione has been shown to be effective as an acylating reagent for the amino group.ATT (1) was readily prepared by several methods, and reacted with various amino compounds in CHCl3, CH2Cl2, THF, EtOH, THF-H2O, or sulfolane to afford the corresponding amides, 2a-w and 3-10 in very high yields within a short time.This reagent exhibits high chemo-selectivity.Its reaction with the diamines 13 and 15 and the triamine 29, which include a primary amino group(s) and a secondary amino group, gave the products acylated only at the primary amino group(s), 14, 16, and 30, respectively, in high yields.Aminoalcohols and aminophenols were chemoselectively converted into acylaminoalcohols and acylaminophenols, respectively, by ATT (1).By utilizing this method, several amide alkaloids (26, 28, 30, and 34) were efficiently synthesized.This new aminolysis can be monitored by the disappearance of the yellow color of the starting materials, ATT (1); it is remarkably characteristic of this reaction. Keywords - monitored aminolysis; 3-acyl-1,3-thiazolidine-2-thione; high chemo-selectivity; amide synthesis; fagaramide; dolicotheline; spermidine; maytenine; N-ferulyltryptamine
- Nagao, Yoshimitsu,Seno, Kaoru,Kawabata, Kohji,Miyasaka, Tadao,Takao, Sachiko,Fujita, Eiichi
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p. 2687 - 2699
(2007/10/02)
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- METHOXYPHENYLTHIOTRIMETHYLSILYLMETHYLLITHIUM A CONVENIENT REAGENT FOR THE HOMOLOGATION OF CARBONYL COMPOUNDS
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A facile homologation procedure for the conversion of carbonyl compounds into ketene-O,S-acetals is described.These intermediers are readily converted into ketene-O-silyl,S-acetals, thioesters, and carboxamides.
- Hackett, Steven,Livinghouse, Tom
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p. 3539 - 3542
(2007/10/02)
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- Rapid Acid-catalysed and Uncatalysed Hydration of Ketenimines
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The rates of hydration of a series of ketenimines (9) have been examined in water (μ 1.0; 25 deg) over the pH range 2-13.Three mechanisms of hydration to the amides (8) were noted: (a) general acid catalysis by proton transfer from H3O(1+) in the pH range 2-7 (giving kH3O(1+)/kD3O(1+) 2.65); (b) general acid catalysis by H2O at pH > 7 (where kH2O/kD2O = 4.8); (c) rate determining HO(1-) attack.The last mechanism was only shown by N-arylketenimines, e.g. (9e); other N-alkylketenimines continue to react by rate-determining proton transfer from water even at pH 13.This result is confirmed by the incorporation of just one deuterium when (9a) reacted in acidic or basic D2O, while the deuteriated ketenimine (9f) does not loose the label on the reaction in water.Substituent effects are parallel for reactions involving H(1+) transfer from H3O(1+) or H2O; the major effects are obtained on changing substituents at carbon (the protonation site).For example, replacement of C-H by C-Me reduces the reactivity by 10-20-fold, while replacement of C-Me by C-Ph reduces the rate of hydration by >100-fold.Ammonium ions also generally react with ketenimines by rate-determining H(1+) transfer to the ketenimine followed by trapping of the nitrilium ion formed by the free amine.Only with the strongest amine base studied (piperidine) does direct nucleophilic attack on the ketenimine compete.
- McCarthy, Daniel G.,Hegarty, Anthony F.
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p. 579 - 591
(2007/10/02)
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