- Amide Bond Formation via the Rearrangement of Nitrile Imines Derived from N-2-Nitrophenyl Hydrazonyl Bromides
-
We report how the rearrangement of highly reactive nitrile imines derived from N-2-nitrophenyl hydrazonyl bromides can be harnessed for the facile construction of amide bonds. This amidation reaction was found to be widely applicable to the synthesis of primary, secondary, and tertiary amides and was used as the key step in the synthesis of the lipid-lowering agent bezafibrate. The orthogonality and functional group tolerance of this approach was exemplified by the N-acylation of unprotected amino acids.
- Boyle, Mhairi,Livingstone, Keith,Henry, Martyn C.,Elwood, Jessica M. L.,Lopez-Fernandez, J. Daniel,Jamieson, Craig
-
supporting information
p. 334 - 338
(2022/01/20)
-
- CuO-decorated magnetite-reduced graphene oxide: a robust and promising heterogeneous catalyst for the oxidative amidation of methylarenes in waterviabenzylic sp3C-H activation
-
A magnetite-reduced graphene oxide-supported CuO nanocomposite (rGO/Fe3O4-CuO) was preparedviaa facile chemical method and characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Brunauer-Emmett-Teller (BET) analysis, vibrating-sample magnetometry (VSM), and thermogravimetric (TG) analysis. The catalytic activity of the rGO/Fe3O4-CuO nanocomposite was probed in the direct oxidative amidation reaction of methylarenes with free amines. Various aromatic and aliphatic amides were prepared efficiently at room temperature from cheap raw chemicals usingtert-butyl hydroperoxide (TBHP) as a “green” oxidant and low-toxicity TBAI in water. This method combines the oxidation of methylarenes and amide bond formation into a single operation. Moreover, the synthesized nanocomposites can be separated from the reaction mixtures using an external magnet and reused in six consecutive runs without a noticeable decrease in the catalytic activity.
- Ebrahimi, Edris,Khalafi-Nezhad, Ali,Khalili, Dariush,Rousta, Marzieh
-
p. 20007 - 20020
(2021/11/12)
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- Synthesis of Benzoisoselenazolones via Rh(III)-Catalyzed Direct Annulative Selenation by Using Elemental Selenium
-
Isoselenazolone derivatives have attracted significant research interest because of their potent therapeutic activities and indispensable applications in organic synthesis. Efficient construction of functionalized isoselenazolone scaffolds is still challenging, and thus new synthetic approaches with improved operational simplicity have been of particular interest. In this manuscript, we introduce a rhodium-catalyzed direct selenium annulation by using stable and tractable elemental selenium. A series of benzamides as well as acrylamides were successfully coupled with selenium under mild reaction conditions, and the obtained isoselenazolones could be pivotal synthetic precursors for several organoselenium compounds. Based on the designed control experiments and X-ray absorption spectroscopy measurements, we propose an unprecedented selenation mechanism involving a highly electrophilic Se(IV) species as the reactive selenium donor. The reaction mechanism was further verified by a computational study.
- Xu-Xu, Qing-Feng,Nishii, Yuji,Uetake, Yuta,Sakurai, Hidehiro,Miura, Masahiro
-
supporting information
p. 17952 - 17959
(2021/11/16)
-
- An unprecedented cobalt-catalyzed selective aroylation of primary amines with aroyl peroxides
-
A novel and facile cobalt-catalyzed selective aroylation of primary amines with aroyl peroxides was developed for the synthesis of aryl amides. It was unprecedented that C[sbnd]N bond formation product was selectively generated without the common N[sbnd]O bond formation product. Aroyl peroxides act as the sole aroylation reagent without additional base or oxidant. The reactions proceeded under mild conditions and showed broad substrates scope with a series of primary amines and aroyl peroxides.
- Li, Dong,Li, Jiale,Li, Juanjuan,Yuan, Songdong,Zhang, Qian
-
supporting information
(2020/09/16)
-
- Tris(o-phenylenedioxy)cyclotriphosphazene as a Promoter for the Formation of Amide Bonds between Aromatic Acids and Amines
-
The atom-efficient formation of amide bonds has emerged as a top-priority research field in organic synthesis, as amide bonds constitute the backbones of proteins and represent an important structural motif in drug molecules. Currently, the increasing demand for novel discoveries in this field has focused substantial attention on this challenging subject. Herein, the degradable 1,3,5-triazo-2,4,6-triphosphorine (TAP) motif is presented as a new condensation system for the dehydrative formation of amide bonds between diverse combinations of aromatic carboxylic acids and amines. The underlying reaction mechanism was investigated, and potential catalyst intermediates were characterized using 31 P NMR spectroscopy and ESI mass spectrometry.
- Movahed, Farzaneh Soleymani,Sawant, Dinesh N.,Bagal, Dattatraya B.,Saito, Susumu
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p. 3253 - 3262
(2020/11/02)
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- Nickel-catalyzed aminocarbonylation of aryl halides with carbamoylsilanes: efficient synthesis of secondary (primary) aromatic amides
-
A nickel-catalyzed aminocarbonylation of aryl halides using carbamoylsilane as an amide source leading to corresponding secondary or primary aromatic amides has been developed, in which the methoxymethyl and benzyl were used as amino protecting group. The protocol tolerates a broad range of aryl halides bearing different functional groups to afford good yields of aryl amides under mild reaction conditions. The types and the relative positions of substituents on the aryl ring make a notable impact on the coupling efficiency. The plausible mechanism of nickel-catalyzed aminocarbonylation has been suggested.
- Chen, Jianxin,Chen, Wenwen,Wen, Xueping
-
-
- An efficient transformation of methyl ethers and nitriles to amides catalyzed by Iron(III) perchlorate hydrate
-
An efficient and inexpensive synthesis of N-substituted amides from the reaction of nitriles with methyl ethers catalyzed by Fe(ClO4)3·H2O is described. Fe(ClO4)3·H2O is an economically efficient catalyst for the Ritter Reaction under solvent-free conditions. A range of methyl ethers (benzyl, sec-alkyl and tert-butyl ethers) were reacted with nitriles to provide the corresponding amides in high–excellent yields.
- Yin, Guibo,Yan, Bin,Chen, Junqing,Ji, Min
-
p. 1355 - 1363
(2019/04/30)
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- FeCl2·4H2O catalyzed ritter reaction with nitriles and halohydrocarbons
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An efficient and inexpensive synthesis of N-substituted amides from the Ritter reaction of nitriles with various halohydrocarbons catalyzed by FeCl2·4H2O is described. FeCl2·4H2O economically efficiently catalyzed the Ritter reaction under solvent-free conditions. A range of halohydrocarbons (benzyl, tert-butyl and sec-alkyl halohydrocarbons) were coupled with nitriles to provide the corresponding amides in high to excellent yields.
- Feng, Cheng-Liang,Yin, Gui-Bo,Yan, Bin,Chen, Jun-Qing,Ji, Min
-
p. 345 - 353
(2019/02/12)
-
- Hydrogen Bond Directed ortho-Selective C?H Borylation of Secondary Aromatic Amides
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Reported is an iridium catalyst for ortho-selective C?H borylation of challenging secondary aromatic amide substrates, and the regioselectivity is controlled by hydrogen-bond interactions. The BAIPy-Ir catalyst forms three hydrogen bonds with the substrate during the crucial activation step, and allows ortho-C?H borylation with high selectivity. The catalyst displays unprecedented ortho selectivities for a wide variety of substrates that differ in electronic and steric properties, and the catalyst tolerates various functional groups. The regioselective C?H borylation catalyst is readily accessible and converts substrates on gram scale with high selectivity and conversion.
- Bai, Shao-Tao,Bheeter, Charles B.,Reek, Joost N. H.
-
supporting information
p. 13039 - 13043
(2019/07/31)
-
- A solid-supported arylboronic acid catalyst for direct amidation
-
An efficient heterogeneous amidation catalyst has been prepared by co-polymerisation of styrene, DVB with 4-styreneboronic acid, which shows wide substrate applicability and higher reactivity than the equivalent homogeneous phenylboronic acid, suggesting potential cooperative catalytic effects. The catalyst can be easily recovered and reused; suitable for use in packed bed flow reactors.
- Du, Yihao,Barber, Thomas,Lim, Sol Ee,Rzepa, Henry S.,Baxendale, Ian R.,Whiting, Andrew
-
supporting information
p. 2916 - 2919
(2019/03/27)
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- Fe(ClO 4) 3 ·h 2 O-Catalyzed Ritter Reaction: A Convenient Synthesis of Amides from Esters and Nitriles
-
An efficient and inexpensive synthesis of N-substituted amides from the Ritter reaction of nitriles with esters catalyzed by Fe(ClO 4) 3 ·H 2 O is described. Fe(ClO 4) 3 ·H 2 O is an economically efficient catalyst for the Ritter reaction under solvent-free conditions. Reactions of a range of esters (benzyl, sec-alkyl, and tert-butyl esters) with nitriles (primary, secondary, tertiary, and aryl nitriles) were performed to provide the corresponding amides in high to excellent yields.
- Feng, Chengliang,Yan, Bin,Yin, Guibo,Chen, Junqing,Ji, Min
-
p. 2257 - 2264
(2018/10/20)
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- Convenient synthesis of amides by Zn(ClO4)2·6H2O catalysed Ritter reaction with nitriles and halohydrocarbons
-
A convenient and high yielding procedure for the synthesis of amides by the Ritter reaction of nitriles and halohydrocarbons in the presence of Zn(ClO4)2·6H2O as a highly stable, effective and available catalyst is described.
- Feng, Chengliang,Yin, Guibo,Yan, Bin,Chen, Junqing,Ji, Min
-
supporting information
p. 383 - 386
(2018/08/21)
-
- Base-promoted amide synthesis from aliphatic amines and ynones as acylation agents through C-C bond cleavage
-
A new protocol for the synthesis of amides via base-promoted cleavage of the C(sp)-C(CO) bond of ynones with aliphatic primary and secondary amines under transition-metal-, ligand-, and oxidant-free conditions has been developed. This method exhibits a wide substrate scope, high functional group tolerance and exclusive chemoselectivity, as well as mild reaction conditions.
- Cheng, Guolin,Lv, Weiwei,Kuai, Changsheng,Wen, Si,Xiao, Shangyun
-
supporting information
p. 1726 - 1729
(2018/02/21)
-
- Diboron-Catalyzed Dehydrative Amidation of Aromatic Carboxylic Acids with Amines
-
Tetrakis(dimethylamido)diboron and tetrahydroxydiboron are herein reported as new catalysts for the synthesis of aryl amides by catalytic condensation of aromatic carboxylic acids with amines. The developed protocol is both simple and highly efficient over a broad range of substrates. This method thus represents an attractive approach for the use of diboron catalysts in the synthesis of amides without having to resort to stoichiometric or additional dehydrating agents.
- Sawant, Dinesh N.,Bagal, Dattatraya B.,Ogawa, Saeko,Selvam, Kaliyamoorthy,Saito, Susumu
-
supporting information
p. 4397 - 4400
(2018/08/09)
-
- Method for preparing amide compound from 2-diazo-1, 3-dicarbonyl compound as acylating agent
-
The invention provides a method for preparing an amide compound from a 2-diazo-1, 3-dicarbonyl compound as an acylating agent under non-metallic catalysis and neutral conditions. The method uses 2-diazo-1, 3-dicarbonyl compound as a raw material and carries out different benzoyl protection on different amino compounds so that a series of amide compounds are prepared. The method is carried out under neutral conditions, prevents the limitation of reaction substrates under conventional alkaline conditions, and has mild reaction conditions, high reaction efficiency and a simple operation method. The method provides a new and convenient method for preparation of amide compounds and protection of amino groups and can be used in the fields of chemical medicine, biology and materials.
- -
-
Paragraph 0052; 0090-0095
(2017/08/28)
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- Palladium-Catalyzed Direct Synthesis of Phenanthridones from Benzamides through Tandem N–H/C–H Arylation
-
We report a palladium-catalyzed method for the direct synthesis of phenanthridones from benzamides in a single step. Unlike previous reports, the current protocol does not need any directing groups or any harsh conditions. This methodology has a wide functional group tolerance therefore a series of phenanthridones were synthesized with a yield up to 87 %. The efficacy of this protocol was further explored by synthesizing some important naturally occurring amaryllidaceae alkaloids in a single step with very good yields.
- Banerji, Biswadip,Chatterjee, Satadru,Chandrasekhar,Nayan, Chinmay,Killi, Sunil Kumar
-
supporting information
p. 5214 - 5218
(2017/09/29)
-
- Palladium-catalyzed carbonylation of aryl halides: An efficient, heterogeneous and phosphine-free catalytic system for aminocarbonylation and alkoxycarbonylation employing Mo(CO)6 as a solid carbon monoxide source
-
Immobilized palladium metal-containing magnetic nanoparticles (ImmPd(0)-MNPs) were synthesized and characterized as an immobilized, phosphine-free catalyst for carbonylation reactions, namely the alkoxycarbonylation and aminocarbonylation reactions. Various substituted aryl iodides tolerated the reaction conditions and a wide variety of alcohols and amines were used efficiently. The effects of the solvent, base, and temperature were studied in both the mentioned reactions. The developed catalytic system avoids the use of phosphine ligands and can be reused for up to eight consecutive cycles. The recycled catalyst was characterized by TEM and ICP analysis.
- Hajipour, Abdol-Reza,Tavangar-Rizi, Zeinab,Iranpoor, Nasser
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p. 78468 - 78476
(2016/09/09)
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- Visible-Light-Mediated Synthesis of Amides from Aldehydes and Amines via in Situ Acid Chloride Formation
-
An efficient visible-light photocatalysis-based one-pot amide synthesis method was developed; visible-light irradiation of a mixture of an aldehyde, tert-butyl hydrogen peroxide, and N-chlorosuccinimide using a Ru(bpy)3Cl2 photocatalyst afforded an acid chloride, which subsequently reacted with amine to yield the corresponding amide. The reaction was used to synthesize moclobemide and a D3 receptor intermediate.
- Iqbal, Naeem,Cho, Eun Jin
-
p. 1905 - 1911
(2016/03/15)
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- Selective catalytic Hofmann: N -alkylation of poor nucleophilic amines and amides with catalytic amounts of alkyl halides
-
Using only catalytic amounts of alkyl halides in the reactions of poor nucleophilic amines/amides and alcohols led to a selective Hofmann N-alkylation reaction catalytic in alkyl halides, providing a practical and efficient method for the practical synthesis of mono- or di-alkylated amines/amides in high selectivities. This new method avoids the use of large amounts of bases, alkyl halides, and solvents, and generates water as the only byproduct. Preliminary mechanistic studies showed that alkyl halides are key intermediates/catalysts regeneratable in the reaction cycle.
- Xu, Qing,Xie, Huamei,Zhang, Er-Lei,Ma, Xiantao,Chen, Jianhui,Yu, Xiao-Chun,Li, Huan
-
supporting information
p. 3940 - 3944
(2016/07/21)
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- C-N Coupling of Amides with Alcohols Catalyzed by N-Heterocyclic Carbene-Phosphine Iridium Complexes
-
N-Heterocyclic carbene-phosphine iridium complexes (NHC-Ir) were developed/found to be a highly reactive catalyst for N-monoalkylation of amides with alcohols via hydrogen transfer. The reaction produced the desired product in high isolated yields using a wide range of substrates with low catalyst loading and short reaction times.
- Kerdphon, Sutthichat,Quan, Xu,Parihar, Vijay Singh,Andersson, Pher G.
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p. 11529 - 11537
(2015/12/04)
-
- A novel nickel-catalyzed synthesis of thioesters, esters and amides from aryl iodides in the presence of chromium hexacarbonyl
-
This study describes our findings on a novel and cheap NiCl2 catalytic system under ligand-free conditions for the efficient thiocarbonylation, alkoxycarbonylation and amidocarbonylation reactions of aryl iodides in the presence of Cr(CO)6 as the solid source of carbon monoxide under air. A variety of aryl iodides tolerated the reaction conditions and structurally different thiols, alcohols and amines were used efficiently. The corresponding thioesters, esters and amides were obtained in good to excellent yield at atmospheric pressure under mild reaction conditions.
- Iranpoor, Nasser,Firouzabadi, Habib,Etemadi-Davan, Elham,Nematollahi, Arash,Firouzi, Hamid Reza
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p. 6445 - 6452
(2015/08/11)
-
- Easy, Green and Safe Carbonylation Reactions through Zeolite-Catalyzed Carbon Monoxide Production from Formic Acid
-
Zeolites with the right shape and acid site density and strength, such as certain ZSM-5 forms, were able to cleanly decompose formic acid to carbon monoxide (CO), and the latter could be directly used in palladium-catalyzed carbonylation reactions. A simple two-reactor system was designed to produce CO conveniently and then further react this gas in a safe way. The two-reactor system is particularly cheap, easy to set up and use. In addition, the carbonylation conditions without pressure allowed for very efficient CO incorporation, with only 1% of palladium(II) chloride (PdCl2) and Xantphos.
- Losch, Pit,Felten, Anne-Sophie,Pale, Patrick
-
supporting information
p. 2931 - 2938
(2015/09/28)
-
- Palladium-catalyzed fluorocarbonylation using N-formylsaccharin as CO source: General access to carboxylic acid derivatives
-
N-Formylsaccharin, an easily accessible crystalline compound, has been employed as an efficient CO source in Pd-catalyzed fluorocarbonylation of aryl halides to afford the corresponding acyl fluorides in high yields. The reactions use a near-stoichiometric amount of the CO source (1.2 equiv) and tolerate diverse functional groups. The acyl fluorides obtained could be readily transformed into various carboxylic acid derivatives such as carboxylic acid, esters, thioesters, and amides in a one-pot procedure.
- Ueda, Tsuyoshi,Konishi, Hideyuki,Manabe, Kei
-
supporting information
p. 5370 - 5373
(2013/11/06)
-
- Palladium-free aminocarbonylation of aryl, benzyl, and styryl iodides and bromides by amines using Mo(CO)6 and norbornadiene
-
A simple and efficient method is described for aminocarbonylation of aryl, benzyl, and styryl iodides and bromides using the in situ generated molybdenum tetracarbonyl norbornadiene [Mo(CO)4(nbd)] complex as a suitable source of carbon monoxide.
- Iranpoor, Nasser,Firouzabadi, Habib,Motevalli, Somayeh,Talebi, Mohsen
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p. 418 - 426
(2013/01/15)
-
- Selective catalytic sp3 C-O bond cleavage with C-N bond formation in 3-alkoxy-1-propanols
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The ruthenium catalyzed selective sp3 C-O cleavage with amide formation was reported in reactions of 3-alkoxy-1-propanol derivatives and amines. The cleavage only occurs at the C3-O position even with 3-benzyloxy-1-propanol. Based on the experimental results, O-bound and C-bound Ru enolate complexes were proposed as key intermediates for the unique selective sp3 C-O bond cleavage in 3-alkoxy-1-propanols.
- Chen, Cheng,Hong, Soon Hyeok
-
supporting information; experimental part
p. 2992 - 2995
(2012/07/28)
-
- Molybdenum-mediated carbonylation of aryl halides with nucleophiles using microwave irradiation
-
Figure Presented. A new, efficient, and practical molybdenum-mediated carbonylation of aryl and heteroaryl halides with a variety of nucleophiles is described using microwave irradiation. A range of reactions illustrating the wide scope of this chemistry were carried out and proceeded in good to excellent yields.
- Roberts, Bryan,Liptrot, David,Alcaraz, Lilian,Luker, Tim,Stocks, Michael J.
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supporting information; experimental part
p. 4280 - 4283
(2010/11/04)
-
- Oxidative amidation and azidation of aldehydes by NHC catalysis
-
Figure presented N-Heterocyclic carbene catalyzed oxidative amidations of various aldehydes to the corresponding hexafluoroisopropylesters by using the readily available organic oxidant A are described. The hexafluoroisopropylesters prepared in situ are shown to be highly useful active esters for amide bond formation. In addition, oxidative azidation of aldehydes is presented. These mild organocatalytic processes do not use any transition metal.
- De Sarkar, Suman,Studer, Armido
-
supporting information; experimental part
p. 1992 - 1995
(2010/07/10)
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- Pd(OAc)2-catalyzed aminocarbonylation of aryl iodides with aromatic or aliphatic amines in water
-
An efficient ligand-free protocol has been developed for the amincocarbonylation of aryl iodides with aromatic/aliphatic amines using palladium(II) acetate as a catalyst in water under milder operating conditions. The system tolerated a wide variety of hindered and functionalized aryl iodides/amines and afforded the desired amides in excellent yields at low catalyst concentration. Georg Thieme Verlag Stuttgart.
- Tambade, Pawan J.,Patil, Yogesh P.,Bhanushali, Mayur J.,Bhanage, Bhalchandra M.
-
experimental part
p. 2347 - 2352
(2009/04/04)
-
- An efficient synthesis of amides and esters via triacyloxyboranes
-
Borane-tetrahydrofuran complex or borane-methyl sulfide complex is used to activate carboxylic acids to generate triacyloxyboranes. The triacyloxyboranes can be effectively reacted with various nucleophiles including alkylamines, arylamines, hydrazides, alcohols and phenols at reflux in toluene to provide the corresponding amides and esters in excellent yield. Aliphatic carboxylic acids are selectively esterified in the presence of aromatic carboxylic acids under the borane conditions. Georg Thieme Verlag Stuttgart.
- Huang, Zhongping,Reilly, John E.,Buckle, Ronald N.
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p. 1026 - 1030
(2008/02/13)
-
- New boron(III)-catalyzed amide and ester condensation reactions
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In 1996, we reported that benzeneboronic acids bearing electron-withdrawing groups at the meta- or para-position are highly effective catalysts for the amide condensation reaction in less-polar solvents. In this paper, we report that N-alkyl-4-boronopyridinium halides are more effective catalysts than the previous ones in more polar solvents. N-Alkyl-4-boronopyridinium halides are effective not only for amide condensation between equimolar mixtures of carboxylic acids and amines but also for the esterification of α-hydroxycarboxylic acids in alcohol solvents. Furthermore, perchlorocatecholborane is more effective than areneboronic acids for the amide condensation of sterically demanding carboxylic acids. In addition, Lewis acid-assisted Br?nsted acid (LBA), which is prepared from a 1:2 M mixture of boric acid and tetrachlorocatechol, is effective for the Ritter reaction from alcohols and nitriles to amides.
- Maki, Toshikatsu,Ishihara, Kazuaki,Yamamoto, Hisashi
-
p. 8645 - 8657
(2008/02/08)
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- 4,5,6,7-Tetrachlorobenzo[d][1,3,2]dioxaborol-2-ol as an effective catalyst for the amide condensation of sterically demanding carboxylic acids
-
4,5,6,7-Tetrachlorobenzo[d][1,3,2]dioxaborole (4a) and 4,5,6,7- tetrachlorobenzo[d][1,3,2]dioxaborol-2-ol (4b) are effective catalysts for the dehydrative amide condensation between an equimolar mixture of carboxylic acids and amines. In particular, these catalysts are greatly superior to 3,5-bis(trifluoromethyl)phenylboronic acid (1) for the amide condensation of sterically demanding carboxylic acids. In contrast, 4c, which is prepared from a 1:2 molar mixture of B(OH)3 and tetrachlorocatechol, is effective as a Lewis acid-assisted Bronsted acid (LBA) catalyst for Ritter reaction.
- Maki, Toshikatsu,Ishihara, Kazuaki,Yamamoto, Hisashi
-
p. 1431 - 1434
(2007/10/03)
-
- Method for catalyzing amidation reactions
-
The invention provides a method of preparing a compound of formula 2 wherein R1 and R6 are as defined herein, by a catalytic amidation process in the presence of added carbon dioxide. The inventive methods show surprising rate enhancement relative to the corresponding uncatalyzed reaction.
- -
-
Page/Page column 13
(2008/06/13)
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- Amidations Using N,N′-Carbonyldiimidazole: Remarkable Rate Enhancement by Carbon Dioxide
-
Carbon dioxide catalyzes the reaction of imidazolides with amines to form amides. A substantial rate enhancement is observed in the presence of CO 2 compared to the CO2-free case. The scope and limitations of this reaction are discussed.
- Vaidyanathan, Rajappa,Kalthod, Vikram G.,Ngo, Duc P.,Manley, Jerad M.,Lapekas, Sean P.
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p. 2565 - 2568
(2007/10/03)
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- Increasing rates and scope of reactions: Sluggish amines in microwave-heated aminocarbonylation reactions under air
-
Commercially available molybdenum hexacarbonyl serves as a convenient and solid carbon monoxide source in palladium-catalyzed aminocarbonylations of aryl bromides and iodides. This improved microwave protocol, relying on DBU as base and THF as solvent, enables rapid couplings using otherwise sluggish anilines, tert-butylamine, and free amino acids. In addition, Cr(CO)6 and W(CO)6 were found to be useful alternative CO-releasing reagents. Altogether, 16 different aromatic amides were synthesized under air in 35-95% yield after only 15 min of controlled microwave irradiation.
- Wannberg, Johan,Larhed, Mats
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p. 5750 - 5753
(2007/10/03)
-
- Dimethylformamide as a carbon monoxide source in fast palladium-catalyzed aminocarbonylations of aryl bromides
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Dimethylformamide (DMF) acts as an efficient source of carbon monoxide and dimethylamine in the palladium-catalyzed aminocarbonylation (Heck carbonylation) of p-tolyl bromide to provide the dimethylamide. Addition of amines to the reaction mixture in excess delivers the corresponding aryl amides in good yields. The amines employed, benzylamine, morpholine, and aniline, all constitute good reaction partners. The reaction proceeds smoothly with bromobenzene and more electron-rich aryl bromides, but electron-deficient aryl bromides fail to undergo aminocarbonylation. The reactions are conducted at 180-190°C for 15-20 min with microwave heating in a reaction mixture containing imidazole and potassium tert-butoxide: the latter is required to promote decomposition of the DMF solvent at a suitable rate. The beneficial effects of controlled microwave irradiation as an energy source for the rapid heating of the carbonylation reaction mixture are demonstrated. The carbonylation procedure reported herein, which relies on the in situ generation of carbon monoxide, serves as a convenient alternative to other carbonylation methods and is particularly applicable to small-scale reactions where short reaction times are desired and the direct use of carbon monoxide gas is impractical.
- Wan, Yiqian,Alterman, Mathias,Larhed, Mats,Hallberg, Anders
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p. 6232 - 6235
(2007/10/03)
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- N-nitrosamide-mediated ritter-type reactions. Part II - The operation of persistent steric and π*-acceptor agostic-type effects
-
Benzyl cations were generated via thermolysis of N-benzyl-N-nitrosopivalamide in molten 2-R-substituted benzonitriles (R = MeO, Me, H, F, Cl, and Br). The corresponding N-2-R-benzonitrilium species, in contrast to their 4-R-benzonitrilium counterparts, underwent limited reaction with pivalate ion to form unsymmetrical diacylamines via rearrangement of their initial imidic anhydrides. The yield of diacylamines, though small, varied systematically with the nature of the R group in a manner suggesting the operation of interesting steric and/or electronic effects on the pivalate ion-nitrilium ion collapse. The ortho-substituent, though present on only one side of the benzonitrilium ion inhibits reaction at both sides via steric hindrance in the near-ground state and steric crowding in the transition state (a persistent steric effect). The proposed electronic effect involves a π*-acceptor agostic-type interaction between n or σ electrons (HOMO) and the π* system (LUMO) of the nitrilium ion. Additionally, in many cases, attack by water on the nitrilium ion occurred to a significantly larger extent than attack by the much more nucleophilic and positionally favored pivalate ion on the same species. This observation is interpreted in terms of the differences in the sizes and docking trajectories of both species with the nitrilium ion due to charge and charge distribution on both nucleophiles.
- Darbeau, Ron W.,Pease, Rebecca S.,Perez, Edson V.,Gibble, Rebekah E.,Ayo, Faith A.,Sweeney, Aaron W.
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p. 2146 - 2153
(2007/10/03)
-
- The Darbeau-White-Gibble reaction: An N-nitrosoamide-mediated Ritter-type reaction. Part I. A study of electronic, steric, and orbital effects in the nucleophile1a
-
Benzyl cations were generated via thermal decomposition of N-benzyl-N-nitrosopivalamide in molten 4-R-substituted benzonitriles (R = NH2, Me2N, MeO, Me, H, F, and CF3). In each case, the benzyl cation was intercepted competitively by pivalate ion to yield benzyl pivalate and by the benzonitriles to yield the corresponding N-4-R-benzonitrilium ion. The latter onium ions reacted with pivalate ion to form benzimidic anhydrides which rearranged to yield N-4-R-benzoyl-N-pivaloylbenzylamines (i.e. unsymmetrical diacylamines). The yield of diacylamines (maximum ~10.6% for R = H) is smaller than from the corresponding reactions in acetonitrile and varied systematically with the nature and location of the R group on the aromatic nucleus. Both electron-releasing and electron-withdrawing groups at the para position effected a diminution of the yield of diacylamine; indeed for R = NH2, no diacylamine was formed. ortho Substitution of the aromatic nucleus resulted in significantly diminished yields of diacylamine, as did nucleophilic attack on the nitrilium ion by pivalate rather than acetate. Thus, both electronic and steric effects in nucleophilic attack on the nitrilium carbon were observed. The ratios of counterion-derived product to solvent-derived product for both the first-formed benzyl cation and the less reactive benzonitrilium ion are similar. This observation is interpreted in terms of the intermediacy of nitrogenous entity-separated ion-pairs in these deaminations.
- Darbeau,Gibble,Pease,Bridges,Siso,Heurtin
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p. 1084 - 1090
(2007/10/03)
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- 3,3'-(Phenylphosphinylidene)bis and 3,3'-(Phenylphosphinylidene)bis. New Activating Agents
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New activating agents, 3,3'-(phenylphophinylidene)bis (4) and 3,3'-(phenylphosphinylidene)bis (5), were readily prepared by the reaction of phenylphosphonic dichloride (3) with 2(3H)-benzoxazolone (1) and 2(3H)-benzothiazolone (2) respectively in the presence of triethylamine at room temperature.The new activating agents 4 and 5 were found to be useful for the preparation of amides, esters, and dipeptides under mild conditions.Furthemore, the direct polycondensation of isophthalic acid with aromatic diamines using the activating agent 4 in the presence of pyridine proceeded fast at room temperature to produce polyamides with inherent viscosities up to 0.80 dL/g.
- Ueda, Mitsuru,Mochizuki, Amane,Hiratsuka, Ichiro,Oikawa, Hideaki
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p. 3291 - 3297
(2007/10/02)
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- Potential Central Nervous System Active Agents. 1. Synthesis of Aromatic N-Benzyl Amides
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The preparation and spectral properties (IR, MS, NMR) are given for 18 aromatic N-benzyl amides, variously substituted on the acyl part, including four new ones and an (E)-cinnamide derivative.The amides were prepared by heating the appropriate N-benzylammonium salt in o-xylene, or from the reaction of the corresponding acid chloride with benzylamine.The occurrence of an intense peak in their mass spectra, which corresponds to the loss of the N-acyl substituent without hydrogen transfer, is reported.
- Agwada, Vincent C.
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p. 479 - 481
(2007/10/02)
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