- Copper-catalyzed enantioselective carbonylation toward α-chiral secondary amides
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Secondary amides are omnipresent structural motifs in peptides, natural products, pharmaceuticals, and agrochemicals. The copper-catalyzed enantioselective hydroaminocarbonylation of alkenes described in this study provides a direct and practical approach for the construction of α-chiral secondary amides. An electrophilic amine transfer reagent possessing a 4-(dimethylamino)benzoate group was the key to the success. This method also features broad functional group tolerance and proceeds under very mild conditions, affording a set of α-chiral secondary amides in high yields (up to 96% yield) with unprecedented levels of enantioselectivity (up to >99% ee). α,β-Unsaturated secondary amides can also be produced though the method by using alkynes as the substrate.
- Wu, Xiao-Feng,Yuan, Yang,Zhao, Fengqian
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p. 12676 - 12681
(2021/10/19)
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- Dehydrogenative amide synthesis from alcohols and amines utilizing N-heterocyclic carbene-based ruthenium complexes as efficient catalysts: The influence of catalyst loadings, ancillary and added ligands
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The metal-catalyzed dehydrogenative coupling of alcohols and amines to access amides has been recognized as an atom-economic and environmental-friendly process. Apart from the formation of the amide products, three other kinds of compounds (esters, imines and amines) may also be produced. Therefore, it is of vital importance to investigate product distribution in this transformation. Herein, N-heterocyclic carbene-based Ru (NHC/Ru) complexes [Ru-1]-[Ru-5] with different ancillary ligands were prepared and characterized. Based on these complexes, we selected condition A (without an added NHC precursor) and condition B (with an added NHC precursor) to comprehensively explore the selectivity and yield of the desired amides. After careful evaluation of various parameters, the Ru loadings, added NHC precursors and the electronic/steric properties of ancillary NHC ligands were found to have considerable influence on this catalytic process.
- Wang, Wan-Qiang,Wang, Zhi-Qin,Sang, Wei,Zhang, Rui,Cheng, Hua,Chen, Cheng,Peng, Da-Yong
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supporting information
(2021/01/05)
-
- Design of oxa-spirocyclic PHOX ligands for the asymmetric synthesis of lorcaserin: Via iridium-catalyzed asymmetric hydrogenation
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Phosphine-oxazoline (PHOX) ligands are a very important class of privileged ligands in asymmetric catalysis. A series of highly rigid oxa-spiro phosphine-oxazoline (O-SIPHOX) ligands based on O-SPINOL was synthesized efficiently, and their iridium complexes were synthesized by coordination of the O-SIPHOX ligands to [Ir(cod)Cl]2 in the presence of sodium tetrakis-3,5-bis(trifluoromethyl)phenylborate (NaBArF). The cationic iridium complexes showed high reactivity and excellent enantioselectivity in the asymmetric hydrogenation of 1-methylene-tetrahydro-benzo[d]azepin-2-ones (up to 99% yield and up to 99% ee). A key intermediate of the anti-obesity drug lorcaserin could be efficiently synthesized using this protocol.
- Ye, Xiang-Yu,Liang, Zhi-Qin,Jin, Cong,Lang, Qi-Wei,Chen, Gen-Qiang,Zhang, Xumu
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p. 195 - 198
(2021/01/14)
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- Radical-Mediated Activation of Esters with a Copper/Selectfluor System: Synthesis of Bulky Amides and Peptides
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Herein, we describe a new approach for the activation of esters via a radical-mediated process enabled by a copper/Selectfluor system. A variety of para-methoxybenzyl esters derived from bulky carboxylic acids and amino acids can be easily converted into the corresponding acyl fluorides, directly used in the one-pot synthesis of amides and peptides. As a proof of concept, this method was applied to the iterative formation of sterically hindered amide bonds.
- Matsumoto, Akira,Wang, Zhe,Maruoka, Keiji
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p. 5401 - 5411
(2021/04/12)
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- Well-defined N-heterocyclic carbene/ruthenium complexes for the alcohol amidation with amines: The dual role of cesium carbonate and improved activities applying an added ligand
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Dehydrogenative amide bond formation from alcohols and amines has been regarded as an atom-economic and sustainable process. Among various catalytic systems, N-heterocyclic carbene (NHC)-based Ru catalytic systems have attracted growing interest due to the outstanding properties of NHCs as ligands. Herein, an NHC/Ru complex (1) was prepared and its structure was further confirmed with X-ray crystallography. In the presence of Cs2CO3, two NHC/Ru-based catalytic systems were disclosed to be active for this amide synthesis. System A, which did not contain any added ligand, required a catalyst loading of 1.00 mol%. Interestingly, improved catalytic performance was realized by the addition of an NHC precursor (L). Optimization of the amounts of L and other conditions gave rise to system B, a much more potent system with the Ru loading as low as 0.25 mol%. Moreover, an NHC-Ru-carbonate complex 6 was identified from the refluxing toluene of 1 and Cs2CO3, and further investigations revealed that 6 was an important intermediate for this catalytic reaction. Based on the above results, we claimed that the role of Cs2CO3 was to facilitate the formation of key intermediate 6. On the other hand, it provided the optimized basicity for the selective amide formation.
- Wang, Wan-Qiang,Yuan, Ye,Miao, Yang,Yu, Bao-Yi,Wang, Hua-Jing,Wang, Zhi-Qin,Sang, Wei,Chen, Cheng,Verpoort, Francis
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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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- Formamide catalyzed activation of carboxylic acids-versatile and cost-efficient amidation and esterification
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A novel, broadly applicable method for amide C-N and ester C-O bond formation is presented based on formylpyrrolidine (FPyr) as a Lewis base catalyst. Herein, trichlorotriazine (TCT), which is the most cost-efficient reagent for OH-group activation, was employed in amounts of ≤40 mol% with respect to the starting material (100 mol%). The new approach is distinguished by excellent cost-efficiency, waste-balance (E-factor down to 3) and scalability (up to >80 g). Moreover, high levels of functional group compatibility, which includes acid-labile acetals and silyl ethers, are demonstrated and even peptide C-N bonds can be formed. In comparison to reported amidation procedures using TCT, yields are considerably improved (for instance from 26 to 91%) and esterification is facilitated for the first time in synthetically useful yields. These significant enhancements are rationalized by activation by means of acid chlorides instead of less electrophilic acid anhydride intermediates.
- Huy, Peter H.,Mbouhom, Christelle
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p. 7399 - 7406
(2019/08/20)
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- Ruthenium-based catalytic systems incorporating a labile cyclooctadiene ligand with N-heterocyclic carbene precursors for the atom-economic alcohol amidation using amines
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Transition-metal-catalyzed amide-bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol.%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further high-resolution mass spectrometry (HRMS) analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.
- Chen, Cheng,Miao, Yang,De Winter, Kimmy,Wang, Hua-Jing,Demeyere, Patrick,Yuan, Ye,Verpoort, Francis
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-
- Efficient N-Heterocyclic Carbene/Ruthenium Catalytic Systems for the Alcohol Amidation with Amines: Involvement of Poly-Carbene Complexes?
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The atom-economic direct amidation of alcohols with amines has been recently highlighted as an attractive and promising transformation. Among the versatile reported catalytic systems, in situ generated N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic systems have demonstrated their advantages such as easy operation and use of commercial Ru compounds. However, the existing catalyst loadings are relatively high, and additional insights for the in situ catalyst generation are still not well-documented. In this work, a variety of benzimidazole-based NHC precursors were initially synthesized. Through the screening of various NHC precursors and other reaction conditions, active in situ catalytic systems were discovered for the efficient amide synthesis. Notably, the catalyst loading is as low as 0.5 mol %. Furthermore, additional experiments were performed to validate the rationale for the superiority of the current catalytic systems over our previous system. It was observed that the ligand structure is one of the reasons for the higher activity. In addition, the higher ratio of the NHC precursor/[Ru] is another important factor for the improvement. Further HR-MS analysis identified the formation of two mono-NHC-Ru species as major species and two Ru species bearing multiple NHC ligands as minor species. Hopefully, the efficient and readily-accessible catalytic systems reported herein could demonstrate great potential for further practical applications.
- Cheng, Hua,Xiong, Mao-Qian,Zhang, Ni,Wang, Hua-Jing,Miao, Yang,Su, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
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p. 4338 - 4345
(2018/09/06)
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- In situ Generated Ruthenium Catalyst Systems Bearing Diverse N-Heterocyclic Carbene Precursors for Atom-Economic Amide Synthesis from Alcohols and Amines
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The transition-metal-catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom-economic process. Among various catalyst systems, in situ generated N-heterocyclic carbene (NHC)-based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active in situ catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron-deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR-scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at δ=?7.8 ppm in the 1H NMR spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the in situ generated catalyst system.
- Cheng, Hua,Xiong, Mao-Qian,Cheng, Chuan-Xiang,Wang, Hua-Jing,Lu, Qiang,Liu, Hong-Fu,Yao, Fu-Bin,Chen, Cheng,Verpoort, Francis
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p. 440 - 448
(2018/02/06)
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- Palladium-Catalyzed Hydrocarbonylative C-N Coupling of Alkenes with Amides
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An efficient palladium-catalyzed hydrocarbonylative C-N coupling of alkenes with amides has been developed. The reaction was performed via hydrocarbonylation of alkenes, followed by acyl metathesis with amides. Both intermolecular and intramolecular react
- Zhou, Xibing,Zhang, Guoying,Gao, Bao,Huang, Hanmin
-
supporting information
p. 2208 - 2212
(2018/04/30)
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- A process for preparing N - alkyl amide method (by machine translation)
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The invention discloses a method for preparing N - alkyl amide of the method. In the reaction container, joins the nitrile, oxime, transition metal catalyst iridium complex [Cp * IrCl2 ]2 , Toluene; the reaction mixture in 100 °C reaction under 6 hours, cooling to room temperature; then the alcohol and alkali compound is added, the reaction mixture in the 130 °C react again under 12 hours later, then through the column separation, to obtain the target compound. The invention from the fully commercialized nitrile, proceed wowo and mellow, in the participation of transition metal iridium catalyst, to directly obtain N - alkyl amide, the reaction exhibits three significant advantages: 1) the use of the commercialization of the starting material; 2) low catalyst load; 3) is environment-friendly and easy to control. Therefore, the reaction in accordance with the requirement of green chemistry, has broad prospects of development. (by machine translation)
- -
-
Paragraph 0156; 0157; 0158; 0159; 0160
(2017/08/19)
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- Palladium-catalyzed highly regioselective hydroaminocarbonylation of aromatic alkenes to branched amides
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Pd(t-Bu3P)2 has been successfully identified as an efficient catalyst for the hydroaminocarbonylation of aromatic alkenes to branched amides under relatively mild reaction conditions. With hydroxylamine hydrochloride as an additive,
- Zhu, Jinping,Gao, Bao,Huang, Hanmin
-
supporting information
p. 2910 - 2913
(2017/04/11)
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- Selective Palladium-Catalyzed Aminocarbonylation of Olefins to Branched Amides
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A general and efficient protocol for iso-selective aminocarbonylation of olefins with aliphatic amines has been developed for the first time. Key to the success for this process is the use of a specific 2-phosphino-substituted pyrrole ligand in the presence of PdX2(X=halide) as a pre-catalyst. Bulk industrial and functionalized olefins react with various aliphatic amines, including amino-acid derivatives, to give the corresponding branched amides generally in good yields (up to 99 %) and regioselectivities (b/l up to 99:1).
- Liu, Jie,Li, Haoquan,Spannenberg, Anke,Franke, Robert,Jackstell, Ralf,Beller, Matthias
-
supporting information
p. 13544 - 13548
(2016/10/21)
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- Rhodium-catalyzed oxidative amidation of allylic alcohols and aldehydes: Effective conversion of amines and anilines into amides
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The rhodium-catalyzed oxidative amidation of allylic alcohols and aldehydes is reported. In situ generated [(BINAP)Rh]BF4 catalyzes the one-pot isomerization/oxidative amidation of allylic alcohols or direct amidation of aldehydes using acetone or styrene as the hydrogen acceptor. The conditions are general, affording good to excellent yields with a wide array of amine and aniline nucleophiles, and chemoselective, other alcohols do not participate in the oxidation reaction. Utilization of biphasic conditions is critical, as they promote an equilibrium between the imine/enamine byproducts and the hemiaminal, which can undergo oxidation to the amide.
- Wu, Zhao,Hull, Kami L.
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p. 969 - 975
(2016/02/05)
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- Method for synthesizing N-alkylamide
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The invention discloses a method for synthesizing N-alkylamide. In a reaction container, adding nitrile, a complex of a transition-metal catalyst gold, a solvent tetrahydrofuran and H2O; reacting a reaction mixture for several hours at the temperature of 130-140 DEG C, cooling the reaction mixture to room temperature, performing vacuum pressure reduction to remove the solvent; adding a compound alcohol, alkali, the complex of a transition-metal catalyst iridium, a solvent toluene, reacting the reaction mixture for several hours at the temperature of 130 DEG C, through column separation, obtaining a target compound. According to the invention, with participation of the transition-metal catalyst, commercial nitrile is hydrolyzed to generate an amide intermediate, and then is subjected to an alkylation reaction with alcohol to obtain N-alkylamide. The reaction has three obvious advantages: 1) the commercial nitrile and alcohol which is almost nontoxic are taken as initial raw materials; 2) only water is generated as a by-product in the reaction, so that the reaction has no harm on environment; and 3) reaction atom economy is high. The reaction accords with green chemistry requirement, and has wide development prospect.
- -
-
Paragraph 0150-0153
(2016/12/07)
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- Boronic acid-DMAPO cooperative catalysis for dehydrative condensation between carboxylic acids and amines
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Arylboronic acid and 4-(N,N-dimethylamino)pyridine N-oxide (DMAPO) cooperatively catalyse the dehydrative condensation reaction between carboxylic acids and amines to give the corresponding amides under azeotropic reflux conditions. This cooperative use is much more effective than their individual use as catalysts, and chemoselectively promotes the amide condensation of (poly)conjugated carboxylic acids. The present method is practical and scalable, and has been applied to the synthesis of sitagliptin and a drug candidate.
- Ishihara, Kazuaki,Lu, Yanhui
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p. 1276 - 1280
(2016/02/05)
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- Combination of gold and iridium catalysts for the synthesis of N-alkylated amides from nitriles and alcohols
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An alternative and efficient approach for the synthesis of N-alkylated amides from nitriles and alcohols was proposed and accomplished. By the combination of [(IPr)Au(NTf2)] (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene) and [CpIrCl2]2 (Cp = η5-pentamethylcyclopentadienyl), a series of nitriles were first hydrated to give amides, in which the resulting amides were further N-alkylated with a variety of alcohols as alkylating agents to afford N-alkylated amides with good to excellent yields. Compared with previous methods for the synthesis of N-alkylated amides from nitriles and alcohols as starting materials, this protocol could be accomplished with high atom economy under more environmentally benign conditions.
- Li, Feng,Ma, Juan,Lu, Lei,Bao, Xiaofeng,Tang, Wanying
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p. 1953 - 1960
(2015/04/27)
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- Comprehensive Study of the Organic-Solvent-Free CDI-Mediated Acylation of Various Nucleophiles by Mechanochemistry
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Acylation reactions are ubiquitous in the synthesis of natural products and biologically active compounds. Unfortunately, these reactions often require the use of large quantities of volatile and/or toxic solvents, either for the reaction, purification or isolation of the products. Herein we describe and discuss the possibility of completely eliminating the use of organic solvents for the synthesis, purification and isolation of products resulting from the acylation of amines and other nucleophiles. Thus, utilisation of N,N′-carbonyldiimidazole (CDI) allows efficient coupling between carboxylic acids and various nucleophiles under solvent-free mechanical agitation, and water-assisted grinding enables both the purification and isolation of pure products. Critical parameters such as the physical state and water solubility of the products, milling material, type of agitation (vibratory or planetary) as well as contamination from wear are analysed and discussed. In addition, original organic-solvent-free conditions are proposed to overcome the limitations of this approach. The calculations of various green metrics are included, highlighting the particularly low environmental impact of this strategy.
- Mtro, Thomas-Xavier,Bonnamour, Julien,Reidon, Thomas,Duprez, Anthony,Sarpoulet, Jordi,Martinez, Jean,Lamaty, Frdric
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supporting information
p. 12787 - 12796
(2015/09/01)
-
- Palladium-catalyzed hydroaminocarbonylation of alkenes with amines: A strategy to overcome the basicity barrier imparted by aliphatic amines
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A novel and efficient palladium-catalyzed hydroaminocarbonylation of alkenes with aminals has been developed under mild reaction conditions, and allows the synthesis of a wide range of N-alkyl linear amides in good yields with high regioselectivity. On the basis of this method, a cooperative catalytic system operating by the synergistic combination of palladium, paraformaldehyde, and acid was established for promoting the hydroaminocarbonylation of alkenes with both aromatic and aliphatic amines, which do not react well under conventional palladium-catalyzed hydroaminocarbonylation. Back to basics: The basicity of aliphatic amines precludes their use in the palladium-catalyzed hydroaminocarbonylation. This issue was overcome by using aminals as surrogates of aliphatic amines. A cooperative catalytic system was discovered to operate by the synergistic combination of palladium, paraformaldehyde, and acid for promotion of the hydroaminocarbonylation of alkenes with both aromatic and aliphatic amines.
- Zhang, Guoying,Gao, Bao,Huang, Hanmin
-
supporting information
p. 7657 - 7661
(2015/06/25)
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- The direct synthesis of N-alkylated amides via a tandem hydration/N-alkylation reaction from nitriles, aldoximes and alcohols
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A novel strategy for the direct synthesis of N-alkylated amides from nitriles, aldoximes and alcohols was proposed and accomplished in the presence of a Cp*Ir complex. This journal is the Partner Organisations 2014.
- Wang, Nana,Zou, Xiaoyuan,Ma, Juan,Li, Feng
-
supporting information
p. 8303 - 8305
(2014/07/22)
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- Ruthenium-catalysed oxidation of alcohols to amides using a hydrogen acceptor
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A wider investigation into the synthesis of secondary amides from primary alcohols using a hydrogen acceptor using commercially available [Ru(p-cymene)Cl2]2 with bis(diphenylphosphino)butane (dppb) as the catalyst. The report looks at over 50 examples with varying functionality and steric bulk, whilst also covering the first reported results using microwave heating to effect the transformation.
- Watson, Andrew J.A.,Wakeham, Russell J.,Maxwell, Aoife C.,Williams, Jonathan M.J.
-
supporting information
p. 3683 - 3690
(2014/05/20)
-
- 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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- 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)
-
- General and scalable amide bond formation with epimerization-prone substrates using T3P and pyridine
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The mild combination of T3P (n-propanephosphonic acid anhydride) and pyridine has been developed for low-epimerization amide bond formation and implemented for the synthesis of a key intermediate to a glucokinase activator. This robust method is general for the coupling of various racemization-prone acid substrates and amines, including relatively non-nucleophilic anilines, and provides amides in high yields with very low epimerization. With easy reaction setup and product isolation, this protocol offers several practical and experimental benefits.
- Dunetz, Joshua R.,Xiang, Yanqiao,Baldwin, Aaron,Ringling, Justin
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supporting information; experimental part
p. 5048 - 5051
(2011/11/29)
-
- Kinetic resolution of racemic carboxylic acids by an L-histidine-derived sulfonamide-induced enantioselective esterification reaction
-
(Chemical Equation Presented) The direct and catalytic kinetic resolution of racemic carboxylic acids bearing a Bronsted base such as O-protected α-hydroxy carboxylic acids and N-protected α-amino acids has been accomplished through an L-histidine-derived sulfonamide-induced enantioselective esterification reaction with tert-butyl alcohol for the first time. Highly asymmetric induction [S(kfast/kslow) = up to 56] has been achieved under the equilibrium between a chiral catalyst and two diastereomeric acylammonium salts through an intramolecular hydrogen-bonding interaction.
- Ishihara, Kazuaki,Kosugi, Yuji,Umemura, Shuhei,Sakakura, Akira
-
supporting information; experimental part
p. 3191 - 3194
(2009/05/27)
-
- Ni-catalyzed mild arylation of α-halocarbonyl compounds with arylboronic acids
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A simple yet powerful Ni catalyst can be used to promote direct arylations of α-halocarbonyl compounds, including a range of esters, amides, and ketones, with various arylboronic acids under mild conditions. The method tolerates β-hydrogens and functional groups in the substrates and offers reactivity and selectivity profiles that are complementary to those found in the well-established Buchwald-Hartwig approach.
- Liu, Chao,He, Chuan,Shi, Wei,Chen, Mao,Lei, Aiwen
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p. 5601 - 5604
(2008/09/17)
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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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- Intramolecular and intermolecular Schmidt reactions of alkyl azides with aldehydes
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Despite recent advances in the use of alkyl azides in ring expansion reactions of ketones, there has been little work done on the corresponding chemistry of aldehydes. In the present study, the Lewis acid-promoted reactions of alkyl azides with aldehydes
- Lee, Huey-Lih,Aubé, Jeffrey
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p. 9007 - 9015
(2008/02/10)
-
- Hydroamidation of alkenes with N-substituted formamides
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Hydroamidation of olefins with N-substituted formamides is performed with dodecacarbonyltriruthenium (Ru3(CO)12) at 180°C under N2 or CO atmosphere in toluene and in a series of ionic liquids. Yields of 99% with 94?97% exo selectivity are found in the addition of N-methylformamide to 2-norbornene under CO both in toluene and in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [bmim][NTf2]. The presence of CO or a phosphine is necessary for significant reaction to occur, with CO more effective than triphenylphosphine in all ionic liquids investigated. Reasonable yields are achieved at low pressures, in contrast to most reported hydroamidations. Conversion, exo-selectivity, and selectivity fall with increasing steric bulk of the N-formamide substituent, and disubstituted formamides are inactive. Of the terminal alkenes investigated, only styrene can be hydroamidated. CSIRO 2006.
- Nath, Dilip Chandra Deb,Fellows, Christopher M.,Kobayashi, Toshiaki,Hayashi, Teruyuki
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p. 218 - 224
(2008/02/02)
-
- 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
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p. 1431 - 1434
(2007/10/03)
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- An efficient method for the preparation of carboxamides by dehydration condensation using tetrakis(1,1,1,3,3,3-hexafluoro-2-propoxy)silane
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The use of tetraalkoxysilanes, particularly tetrakis(perfluoroalkoxy) silanes, in dehydration condensation of carboxylic acids with amines was investigated. Tetrakis(1,1,1,3,3,3-hexafluoro-2-propoxy)silane, Si[OCH(CF 3)2]4, prepared easily from silicon tetrachloride and sodium 1,1,1,3,3,3-hexafluoro-2-propoxide, was found to be an effective dehydrating reagent for preparing various carboxamides in good to high yields from the corresponding carboxylic acids and amines. Copyright
- Tozawa, Takashi,Yamane, Yoshinobu,Mukaiyama, Teruaki
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p. 1586 - 1587
(2007/10/03)
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- The effective use of substituted benzoic anhydrides for the synthesis of carboxamides
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Various carboxamides are synthesized from the corresponding carboxylic acids and amines with high product-selectivities using 2-methyl-6-nitrobenzoic or 2,4,6-trichlorobenzoic anhydride in the presence of 4-(dimethylamino) pyridine.
- Shiina, Isamu,Kawakita, Yo-Ichi
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p. 4729 - 4733
(2007/10/03)
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- A convenient method for the preparations of carboxamides and peptides by using di(2-pyridyl) carbonate and O,O′-di(2-pyridyl) thiocarbonate as dehydrating reagents
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Preparations of carboxamides and peptides are performed in high yields from free carboxylic acids and amines by dehydration condensation using di(2-Pyridyl) carbonate (DPC) or O,O′-Di(2-Pyridyl) thiocarbonate (DPTC) in the presence of a catalytic amount of 4-(dimethylamino)pyridine (DMAP). The formation of 2-Pyridyl esters, key intermediates of the reaction, from carboxylic acids by using DPC proceeded faster than by using DPTC; therefore, the former carbonate is more efficiently employed in the above condensation reactions.
- Shiina,Suenaga,Nakano,Mukaiyama
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p. 2811 - 2818
(2007/10/03)
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- A facile synthesis of carboxamides by dehydration condensation between free carboxylic acids and amines using O,O′-DI(2-pyridyl) thiocarbonate as a coupling reagent
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Carboxamides are prepared in high yields by dehydration condensation between nearly equimolar amounts of free carboxylic acids and amines both of which involve secondary or tertiary alkyl substituted ones with O,O′-di(2-pyridyl) thiocarbonate, a coupling reagent, in the presence of a catalytic amount of 4-(dimethylamino)pyridine.
- Shiina, Isamu,Saitoh, Katsuyuki,Nakano, Masakazu,Suenaga, Yoshihito,Mukaiyama, Teruaki
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p. 621 - 630
(2007/10/03)
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- The anticonvulsant activities of functionalized N-benzyl 2-acetamidoacetamides. The importance of the 2-acetamido substituent
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Recent studies have demonstrated that substituted N-benzyl 2-acetamidoacetamides provide significant protection against maximal electroshock (MES)-induced seizures in mice and rats. In this study, we investigated whether the 2-acetamido moiety was necessary for anticonvulsant activity. Ten derivatives of the known anticonvulsant, N-benzyl 2-acetamido-2-phenylacetamide were prepared in which the 2-acetamido group was replaced by hydrogen, methyl, oxygen, and halogen substituents. Evaluation of these compounds in the MES-induced seizure test demonstrated that both the hydroxy and the methoxy compounds provided full protection against MES-induced seizures in mice given ip at 100 mg/g. Moreover, evaluation of the individual stereoisomers for the hydroxy compound showed that the principal activity resided in the (R)-isomer. These findings demonstrated that the 2-acetamido substituent is important but not obligatory for the prevention of MES-induced seizures. Further supporting evidence was provided by comparing the pharmacological activities of N-benzyl 2,3-dimethoxypropionamide with N-benzyl 2-acetamido-3-methoxypropionamide. The ED50 value for the former in the MES test was 3.0 mg/kg (ip), which compared favorably with phenobarbital (ED50=22 mg/kg), but the ED50 value for N-benzyl 2-acetamido-3-methoxypropionamide was 8.3 mg/kg.
- Choi, Daeock,Stables, James P.,Kohn, Harold
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p. 2105 - 2114
(2007/10/03)
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- CHIRAL-OPTICAL CHARACTERISTICS OF R-(-)-HYDRATROPANILIDES
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The significant Cotton effect in the unsubstituted and para-substituted anilides of R-(-)-hydratropic acid in the region of the absorption band for the anilide chromophore (240-250 nm) is explained by the interaction of this chromophore with the aromatic
- Potapov, V. M.,Dem'yanovich, V. M.,Solov'eva, L. D.,Ivannikov, S. V.
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p. 2240 - 2245
(2007/10/02)
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- DODECACARBONYLTRIRUTHENIUM CATALYSED CARBONYLATION OF AMINES AND HYDROAMIDATION OF OLEFINS
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Dodecacarbonyltriruthenium (Ru3(CO)12) is an effective homogeneous catalyst precursor for the carbonylation of amines and hydroamidation of olefins under a carbon monoxide pressure of 40 kg cm-2 at 120-180 deg C.By the carbonylation of benzylamine, N- benzylformamide was obtained in 77percent yield. 1-Octene was hydroamidated with benzylamine to N-benzylnonanamide in 67percent yield (the selectivity to its linear isomer was 81percent).These reactions appear to include ruthenium carbamoyl complex as the common key intermediate.
- Tsuji, Yasushi,Ohsumi, Tatsuya,Kondo Teruyuki,Watanabe, Yoshihisa
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p. 333 - 344
(2007/10/02)
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