- A simple route to side-chain fluorinated β-lactams from ring-fluorinated aziridines
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β-Lactams bearing a Ph2CF substituent at the C(4)-atom were synthesized from N-alkyl-2-fluoro-3,3-diphenylaziridines. The transformation was realized using SbF3-mediated isomerization of the monofluoroaziridines to fluorinated aldimines, followed by Staudinger reaction with ketenes. It was shown that this reaction sequence can be performed as a one-pot procedure.
- Konev, Alexander S.,Novikov, Mikhail S.,Khlebnikov, Alexander F.,Tehrani, Kourosch Abbaspour
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- Water-Tolerant and Atom Economical Amide Bond Formation by Metal-Substituted Polyoxometalate Catalysts
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A simple, safe, and inexpensive amide bond formation directly from nonactivated carboxylic acids and free amines is presented in this work. Readily available Zr(IV)- and Hf(IV)-substituted polyoxometalates (POM) are shown to be catalysts for the amide bond formation reaction under mild conditions, low catalyst loading, and without the use of water scavengers, dry solvents, additives for facilitating the amine attack, or specialized experimental setups commonly employed to remove water. Detailed mechanistic investigations revealed the key role of POM scaffolds which act as inorganic ligands to protect Zr(IV) and Hf(IV) Lewis acidic metals against hydrolysis and preserve their catalytic activity in amide bond formation reactions. The catalysts are compatible with a range of functional groups and heterocycles useful for medicinal, agrochemical, and material chemists. The robustness of the Lewis acid-POM complexes is further supported by the catalyst reuse without loss of activity. This prolific combination of Zr(IV)/Hf(IV) and POMs inaugurates a powerful class of catalysts for the amide bond formation, which overcomes key limitations of previously established Zr(IV)/Hf(IV) salts and boron-based catalysts.
- De Azambuja, Francisco,Parac-Vogt, Tatjana N.
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p. 10245 - 10252
(2019/11/03)
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- 9-Silafluorenyl Dichlorides as Chemically Ligating Coupling Agents and Their Application in Peptide Synthesis
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A fundamentally simple, mild, and practical procedure for peptide bond formation is reported that employs a stoichiometric amount of easy-to-access 9-silafluorenyl dichlorides as the coupling agent. Without initial preactivation or elaboration of the carboxylic acid or amine termini of the amino acids, the developed reagent is proposed to act through an unprecedented chemical ligation mechanism, bringing the two coupling partners together before being subsequently eliminated. The desired amides or peptide bonds are thus furnished in good yields and with low to no epimerization.
- Aspin, Samuel J.,Taillemaud, Sylvain,Cyr, Patrick,Charette, André B.
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supporting information
p. 13833 - 13837
(2016/10/26)
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- Ce(III) immobilised on aminated epichlorohydrin-activated agarose matrix - "green" and efficient catalyst for transamidation of carboxamides
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The present study reports the preparation and characterisation of Ce(III) immobilised on an aminated epichlorohydrin-activated agarose matrix (CAEA) as a "green" catalyst. The catalyst was synthesised by the reaction of the epichlorohydrin-activated agarose matrix with ammonia solution, which was then treated with Ce(NO3)3 · 6H2O. The catalyst (CAEA) was characterised by FT-IR, far IR, CHN, XRD, TGA, and ICP techniques. CAEA is shown to be an effective and reusable heterogeneous catalyst for the transamidation of carboxamides with amines under solventfree conditions. The catalyst was successfully applied to the synthesis of a wide range of aromatic and aliphatic amides. High efficiency, mild reaction conditions, easy work-up, simple separation and also reusability are important advantages of this catalyst.
- Zarei, Zeinab,Akhlaghinia, Batool
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p. 1421 - 1437
(2015/09/15)
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- A One-Pot, fast, and efficient amidation of carboxylic acids, α-amino acids and sulfonic acids using pph3/n-chlorobenzotriazole system
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Triphenylphosphine (PPh3)/N-chlorobenzotriazole (NCBT), and amine (primary and secondary aliphatic amines and also substituted anilines) in CH2Cl2 efficiently converted carboxylic acids, α-amino acids, and sulfonic acids to the corresponding amides and sulfonamides at room temperature. Good to excellent yields, inexpensive, and fast reaction conditions are the important features of this procedure.
- Rouhi-Saadabad, Hamed,Akhlaghinia, Batool
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p. 1703 - 1714
(2015/09/15)
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- Catalytic chemical amide synthesis at room temperature: One more step toward peptide synthesis
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An efficient method has been developed for direct amide bond synthesis between carboxylic acids and amines via (2-(thiophen-2-ylmethyl)phenyl)boronic acid as a highly active bench-stable catalyst. This catalyst was found to be very effective at room temperature for a large range of substrates with slightly higher temperatures required for challenging ones. This methodology can be applied to aliphatic, α-hydroxyl, aromatic, and heteroaromatic acids as well as primary, secondary, heterocyclic, and even functionalized amines. Notably, N-Boc-protected amino acids were successfully coupled in good yields with very little racemization. An example of catalytic dipeptide synthesis is reported.
- Mohy El Dine, Tharwat,Erb, William,Berhault, Yohann,Rouden, Jacques,Blanchet, Jér?me
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p. 4532 - 4544
(2015/05/13)
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- Microwave assisted efficient aminocarbonylation of N-tosylhydrazones with molybdenum hexacarbonyl and amines
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An efficient aminocarbonylation of N-tosylhydrazones derived from aromatic aldehydes and ketones mediated by molybdenum hexacarbonyl is reported. This method is palladium-free and provides a rapid access to the α-aryl acetamides in moderate to good yields.
- Rao, K. Penta,Basak, Ashok K.,Raju, Amancha,Patil, Vikas S.,Reddy, L. Krishnakanth
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p. 5510 - 5513
(2013/09/23)
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- Direct synthesis of amides from carboxylic acids and amines using B(OCH2CF3)3
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B(OCH2CF3)3, prepared from readily available B2O3 and 2,2,2-trifluoroethanol, is as an effective reagent for the direct amidation of a variety of carboxylic acids with a broad range of amines. In most cases, the amide products can be purified by a simple filtration procedure using commercially available resins, with no need for aqueous workup or chromatography. The amidation of N-protected amino acids with both primary and secondary amines proceeds effectively, with very low levels of racemization. B(OCH2CF3)3 can also be used for the formylation of a range of amines in good to excellent yield, via transamidation of dimethylformamide.
- Lanigan, Rachel M.,Starkov, Pavel,Sheppard, Tom D.
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p. 4512 - 4523
(2013/06/05)
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- 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
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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
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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
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p. 1431 - 1434
(2007/10/03)
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- A simple and convenient procedure for the conversion of esters to secondary amides
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An improved procedure has been developed for the direct conversion of carboxylic esters to secondary amides by simple treatment with primary amines in presence of indium triiodide.
- Ranu, Brindaban C.,Dutta, Pinak
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p. 297 - 301
(2007/10/03)
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- Versatile Acylation of N-Nucleophiles Using a New Polymer-Supported 1-Hydroxybenzotriazole Derivative
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The synthesis of a new polymer-supported coupling reagent derived from 1-hydroxybenzotriazole is described. An aminomethylated polystyrene was functionalized by reaction with 3-nitro-4- chlorobenzenesulfonyl chloride (2) followed by treatement with hydrazine hydrate, to give the polymeric N-benzyl-1-hydroxybenzotriazole-6-sulfonamide (4).The polymeric reagent 4 was shown to be highly efficient for the synthesis of amides. The efficiency of 4 could be attributed to its high acidity, conferred by the sulfonyl moiety. The procedure for amide synthesis involves the formation of an activated ester on the derivatized polymer followed, in a second step, by treatment with an amine to generate the amide in solution. Simple filtration allows the separation of the product from the polymeric reagent which in this case plays the role of leaving group. An optimization study of this two-step procedure was performed. As amides are obtained in solution free of reaction byproducts, this method can be used in an automated procedure to recover them directly into a 96 well plate, ready to be used in high throughput screening assays. Thus 4 was shown to be particularly suitable for the high throughput parallel synthesis of amides libraries.
- Pop, Iuliana E.,Déprez, Beno?t P.,Tartar, André L.
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p. 2594 - 2603
(2007/10/03)
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- Spiro β-Lactam Thiadiazoline and Triazoline Systems. Comparison with the Chemistry of Spiro β-Lactam Oxadiazolines
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Triazoline, oxadiazoline, and thiadiazoline ring systems spiro-fused to C4 of a β-lactam ring undergo 1,3-dipolar cycloreversion to form azomethine-, carbonyl-, and thiocarbonyl ylides, respectively.The order of reactivities is triazoline>thiadiazoline>oxadiazoline.
- Zoghbi, Michel,Warkentin, John
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p. 10229 - 10238
(2007/10/02)
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- Acylation reactions mediated by tantalum carboxylates
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Facile nucleophilic attack on coordinated carboxylate ligaods is reported: complexes of tantalum(V) react rapidly with amines and amino acid esters to give the corresponding amides. Cyclopentadienyltantalum(V) amino acid carboxylate complexes have been pr
- Joshi, Kiran,Bao, Jiang,Goldman, Alan S.,Kohn, Joachim
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p. 6649 - 6652
(2007/10/02)
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- 1-(o-NITROPHENYLSULPHONYLOXY)BENZOTRIAZOLE, REAGENT FOR THE CONDENSATION OF CARBOXYLIC ACIDS WITH AMINES
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With the Schotten-Baumann reaction we have synthesized 1-(o-nitrophenylsulfonyloxy)benzotriazole and have shown its suitability for the synthesis of esters of 1-hydroxybenzotriazole and carboxylic amides, and also of peptides.
- Topuzyan, V. O.,Martirosyan, M. S.
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p. 2148 - 2153
(2007/10/02)
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