- Ni-Catalyzed Regiodivergent and Stereoselective Hydroalkylation of Acyclic Branched Dienes with Unstabilized C(sp3) Nucleophiles
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Two complementary regiodivergent [(P,N)Ni]-catalyzed hydroalkylations of branched dienes are reported. When amides are employed as unstabilized C(sp3) nucleophiles, a highly regioselective 1,4-addition process is favored. The addition products are obtained in high yield and with excellent stereocontrol of the internal olefin. With use of a chiral ligand and imides as carbon nucleophiles, a 3,4-addition protocol was developed, enabling construction of two contiguous tertiary stereocenters in a single step with moderate to high levels of diastereocontrol and excellent enantiocontrol. Both methods operate under mild reaction conditions, display a broad scope, and show excellent functional group tolerance. The synthetic potential of the 3,4-hydroalkylation reaction was established via a series of postcatalytic modifications.
- Shao, Wen,Besnard, Céline,Guénée, Laure,Mazet, Clément
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p. 16486 - 16492
(2020/10/26)
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- Ruthenium-Catalyzed Oxidative Amidation of Alkynes to Amides
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Complex CpRuCl(PPh3)2 catalyzes reactions of terminal alkynes with 4-picoline N-oxide and primary and secondary amines to afford the corresponding amides. The reactions occur in chlorinated solvent and aqueous medium, showing applications in peptide chemistry. Stoichiometric studies reveal that the true catalysts of the processes are the vinylidene cations [CpRu(=C=CHR)(PPh3)2]+ which are oxidized to the Ru(η2-CO)-ketenes by the N-oxide. Finally, nucleophilic additions of primary and secondary amines to the free ketenes yield the corresponding amides.
- álvarez-Pérez, Andrea,Esteruelas, Miguel A.,Izquierdo, Susana,Varela, Jesús A.,Saá, Carlos
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supporting information
p. 5346 - 5350
(2019/07/08)
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- CuH-Catalyzed Asymmetric Hydroamidation of Vinylarenes
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A CuH-catalyzed enantioselective hydroamidation reaction of vinylarenes has been developed using readily accessible 1,4,2-dioxazol-5-ones as electrophilic amidating reagents. This method provides a straightforward and efficient approach to synthesize chiral amides in good yields with high levels of enantiopurity under mild conditions. Moreover, this transformation tolerates substrates bearing a broad range of functional groups.
- Zhou, Yujing,Engl, Oliver D.,Bandar, Jeffrey S.,Chant, Emma D.,Buchwald, Stephen L.
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supporting information
p. 6672 - 6675
(2018/06/11)
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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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- 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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- 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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- Thermodynamics of phenylacetamides synthesis: Linear free energy relationship with the pK of amine
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The effective equilibrium constants K′C expressed through the total concentrations of the reagents for the synthesis of N-phenylacetyl-derivatives in aqueous medium from phenylacetic acid and various primary amino compounds have been determined with penicillin acylase as a catalyst. Broad specificity of penicillin acylase (EC 3.5.1.11) to amino components made possible to investigate the acylation of primary amines with different structures and physicochemical properties. Analysis of different components of the effective standard Gibbs energy change ΔGC o′ has revealed favorable thermodynamics for the synthesis of phenylacetamides from unionized substrates forms, however the ionization of reactants carboxy and amino groups in aqueous solutions pushes the equilibrium position to the hydrolysis especially in case of highly basic amines. A linear correlation between the standard Gibbs energy change for amide bond formation from the unionized reagents species and the basicity of amino group was observed: ΔGTo=-3.56pKamine+7.71(kJ/mol). The established linear free energy relationship (LFER) allows to predict the thermodynamic parameters for direct condensation of phenylacetic acid with any amine of known pK. Condensation of phenylacetic acid and amines with pK value within 1.5-8.5 was shown to be thermodynamically favorable in homogeneous aqueous solution. .
- Guranda, Dorel T.,Ushakov, Gennadij A.,Yolkin, Petr G.,Svedas, Vytas K.
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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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- Titanium(IV) isopropoxide as an efficient catalyst for direct amidation of nonactivated carboxylic acids
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Secondary and tertiary amides are formed in high yields, in an efficient and environmentally benign titanium(IV) isopropoxide catalyzed direct amidation of carboxylic acids with primary and secondary amines. Georg Thieme Verlag Stuttgart ? New York.
- Lundberg, Helena,Tinnis, Fredrik,Adolfsson, Hans
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supporting information
p. 2201 - 2204
(2012/10/30)
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- Direct amide coupling of non-activated carboxylic acids and amines catalysed by zirconium(IV) chloride
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Amidst the green: A green, mild and effective protocol for the direct formation of secondary and tertiary amides from non-activated carboxylic acids and amines in good to excellent yields by employing ZrCl4 as the catalyst is presented (see scheme). The amide coupling protocol proved to be suitable for scaled up syntheses, and the mild reaction conditions conserve the enantiopurity of chiral starting materials. Copyright
- Lundberg, Helena,Tinnis, Fredrik,Adolfsson, Hans
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supporting information; experimental part
p. 3822 - 3826
(2012/05/20)
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- Borate esters as convenient reagents for direct amidation of carboxylic acids and transamidation of primary amides
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Simple borates serve as effective promoters for amide bond formation with a variety of carboxylic acids and amines. With trimethyl or tris(2,2,2- trifluoroethyl) borate, amides are obtained in good to excellent yield and high purity after a simple work-up procedure. Tris(2,2,2-trifluoroethyl) borate can also be used for the straightforward conversion of primary amides to secondary amides via transamidation. The Royal Society of Chemistry 2011.
- Starkov, Pavel,Sheppard, Tom D.
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supporting information; experimental part
p. 1320 - 1323
(2011/04/23)
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- METHOD FOR PREPARATION OF AMIDES FROM ALCOHOLS AND AMINES BY EXTRUSION OF HYDROGEN
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The present invention relates to a method for preparation of carboxamides using alcohols and amines as starting materials in a dehydrogenative coupling reaction catalyzed by a ruthenium N-heterocyciic carbene (NHC) complex, which may be prepared in situ.
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Page/Page column 9
(2012/01/13)
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- Amide synthesis from alcohols and amines catalyzed by ruthenium N-Heterocyclic carbene complexes
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The direct synthesis of amides from alcohols and amines is described with the simultaneous liberation of dihydrogen. The reaction does not require any stoichiometric additives or hydrogen acceptors and is catalyzed by ruthenium N-heterocyclic carbene complexes. Three different catalyst systems are presented that all employ 1,3-diisopropylimidazol-2-ylidene (IiPr) as the carbene ligand. In addition, potassium iert-butoxide and a tricycloalkylphosphine are required for the amidation to proceed. In the first system, the active catalyst is generated in situ from [RuCl2(cod)] (cod = 1,5-cyclooctadiene), 1,3-diisopropylimidazolium chloride, tricyclopentylphosphonium tetrafluoroborate, and base. The second system uses the complex [RuCl 2(IiPr)(p-cymene)] together with tricyclohexylphosphine and base, whereas the third system employs the Hoveyda-Grubbs lst-generation metathesis catalyst together with 1,3-diisopropylimidazolium chloride and base. A range of different primary alcohols and amines have been coupled in the presence of the three catalyst systems to afford the corresponding amides in moderate to excellent yields. The best results are obtained with sterically unhindered alcohols and amines. The three catalyst systems do not show any significant differences in reactivity, which indicates that the same catalytically active species is operating. The reaction is believed to proceed by initial dehydrogenation of the primary alcohol to the aldehyde that stays coordinated to ruthenium and is not released into the reaction mixture. Addition of the amine forms the hemiaminal that undergoes dehydrogenation to the amide. A catalytic cycle is proposed with the {(I(Pr)RuII} species as the catalytically active components.
- Dam, Johan Hygum,Osztrovszky, Gyorgyi,Nordstrom, Lars Ulrik,Madsen, Robert
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supporting information; experimental part
p. 6820 - 6827
(2010/08/07)
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- Stereoselective synthesis of 3,4-diaryl β-lactams
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Novel 3,4-diaryl β-lactams were prepared with high stereoselectivity in an efficient manner by a palladium-catalyzed [2+2] carbonylative cycloaddition of benzyl halides with heteroarylidene amines. The type of alkyl group linked to the nitrogen atom influences the reaction's stereoselectivity. Moreover, using chiral imines, separable diastereomeric mixtures of chiral 3,4-diaryl-β-lactams were isolated with good yields and high trans diastereoselections.
- Troisi, Luigino,Pindinelli, Emanuela,Strusi, Valentina,Trinchera, Piera
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experimental part
p. 368 - 374
(2009/07/25)
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- An 'easy-on, easy-off' protecting group for the enzymatic resolution of (±)-1-phenylethylamine in an aqueous medium
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A new approach has been developed for the biocatalytic resolution of (±)-1-phenylethylamine in 100% aqueous medium based on two integrated enzymatic steps: protection and deprotection of the reactive amine enantiomer catalyzed by the same enzyme-penicillin acylase from Alcaligenes faecalis. An 'easy-on, easy-off' protecting group has been introduced using (R)-phenylglycine amide as the acyl donor. (R)-Phenylglycyl-substituted (R)-1-phenylethylamine was poorly soluble and precipitated at enzymatic acylation in an alkaline medium (pH 10-11), driving the synthesis towards high yields. Conversely at pH 7.5, its solubility was continuously increasing, which rendered the subsequent deacylation by the same enzyme highly efficient. In contrast to the resolutions, which employ one biocatalytic step, the new approach made it possible to exploit two sequential enantioselective enzymatic reactions implementing a double enantioselectivity control. Effective enzymatic resolution of (±)-1-phenylethylamine in an aqueous medium was performed with (R)-phenylglycine amide as an acyl donor using the suggested approach.
- Guranda, Dorel T.,Khimiuk, Andrey I.,Van Langen, Luuk M.,Van Rantwijk, Fred,Sheldon, Roger A.,Svedas, Vytas K.
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p. 2901 - 2906
(2007/10/03)
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- A NEW CHIRAL RECOGNITION IN AMINOLYSIS OF 3-ACYL-4(R)-METHOXYCARBONYL-1,3-THIAZOLIDINE-2-THIONE WITH RACEMIC AMINES
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A chiral recognition was observed in aminolysis of 3-acyl-4(R)-methoxycarbonyl-1,3-thiazolidine-2-thione 1 by racemic amine 2 to give an optically active amide (S-excess) and amine (R-excess).
- Nagao, Yoshimitsu,Yagi, Masahiro,Ikede, Takao,Fujita, Eiichi
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p. 201 - 204
(2007/10/02)
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