- A CO2-Catalyzed Transamidation Reaction
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Transamidation reactions are often mediated by reactive substrates in the presence of overstoichiometric activating reagents and/or transition metal catalysts. Here we report the use of CO2as a traceless catalyst: in the presence of catalytic amounts of CO2, transamidation reactions were accelerated with primary, secondary, and tertiary amide donors. Various amine nucleophiles including amino acid derivatives were tolerated, showcasing the utility of transamidation in peptide modification and polymer degradation (e.g., Nylon-6,6). In particular,N,O-dimethylhydroxyl amides (Weinreb amides) displayed a distinct reactivity in the CO2-catalyzed transamidation versus a N2atmosphere. Comparative Hammett studies and kinetic analysis were conducted to elucidate the catalytic activation mechanism of molecular CO2, which was supported by DFT calculations. We attributed the positive effect of CO2in the transamidation reaction to the stabilization of tetrahedral intermediates by covalent binding to the electrophilic CO2
- Yang, Yang,Liu, Jian,Kamounah, Fadhil S.,Ciancaleoni, Gianluca,Lee, Ji-Woong
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p. 16867 - 16881
(2021/11/18)
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- Method for synthesizing amide by using methyl arene and amine in water phase
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The invention provides a high-efficient method of synthesizing amide with methyl aromatics and amine. In the method, with the methyl aromatics and the amine as the raw materials in the water phase and TBHP and TBAI respectively as an oxidizing agent and a catalyst, a sp3 C-H bond and a sp3 N-H bond are broken and a C-N bond is formed. Compared with a conventional method of synthesizing the amide from oxidized amide, in which an activated acyl group or amine is required, the method is carried out with water as the solvent so that the method is not only economical but also environmental-protective. The method has a very good application prospect in the field of synthesizing polypeptide, protein and drugs in future.
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-
Paragraph 0015; 0025-0028
(2021/03/06)
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- Mechanochemical Palladium-Catalyzed Carbonylative Reactions Using Mo(CO)6
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Esters and amides were mechanochemically prepared by palladium-catalyzed carbonylative reactions of aryl iodides by using molybdenum hexacarbonyl as a convenient solid carbonyl source and avoiding a direct handling of gaseous carbon monoxide. Real-time monitoring of the mechanochemical reaction by in situ pressure sensing revealed that CO is rapidly transferred from Mo(CO)6 to the active catalytic system without significant release of molecular carbon monoxide.
- van Bonn, Pit,Bolm, Carsten,Hernández, José G.
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p. 2576 - 2580
(2020/02/20)
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- Rapid Organocatalytic Formation of Carbon Monoxide: Application towards Carbonylative Cross Couplings
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Herein, the first organocatalytic method for the transformation of non-derivatized formic acid into carbon monoxide (CO) is introduced. Formylpyrrolidine (FPyr) and trichlorotriazine (TCT), which is a cost-efficient commodity chemical, enable this decarbonylation. Utilization of dimethylformamide (DMF) as solvent and catalyst even allows for a rapid CO generation at room temperature. Application towards four different carbonylative cross coupling protocols demonstrates the high synthetic utility and versatility of the new approach. Remarkably, this also comprehends a carbonylative Sonogashira reaction at room temperature employing intrinsically difficult electron-deficient aryl iodides. Commercial 13C-enriched formic acid facilitates the production of radiolabeled compounds as exemplified by the pharmaceutical Moclobemide. Finally, comparative experiments verified that the present method is highly superior to other protocols for the activation of carboxylic acids.
- Zoller, Ben,Zapp, Josef,Huy, Peter H.
-
supporting information
p. 9632 - 9638
(2020/07/13)
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- Triethyl Phosphite/Benzoyl Peroxide Mediated Reductive Dealkylation of O-Benzoylhydroxylamines: A Cascade Synthesis of Secondary Amides
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A new triethyl phosphite/benzoyl peroxide (BPO) mediated system has been developed for the synthesis of secondary amides with good to excellent yields in a single step. This unprecedented cascade process involves sequential reduction of N–O bond and benzoylation followed by dealkylation of N–C bond of O-benzoylhydroxylamines (O-BHA). The methodology is versatile as it tolerates a variety of aromatic and aliphatic O-BHA as substrates to access secondary amides.
- Aegurla, Balakrishna,Mandle, Ram D.,Shinde, Prasad G.,Parit, Ratan S.,Kamble, Sanjay P.,Sudalai, Arumugam,Senthilkumar, Beeran
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supporting information
p. 4235 - 4238
(2020/07/04)
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- 5-Bromo-norborn-2-en-7-one derivatives as a carbon monoxide source for palladium catalyzed carbonylation reactions
-
Norbornenone (5b), obtained from the reaction of 2,5-dimethyl-3,4-diphenylcyclopentadienone dimer (3) with bromomaleic anhydride (4b), provides an excellent base-triggered source of carbon monoxide for palladium-catalysed carbonylation reactions. Aminocarbonylation, ketoamide synthesis, and Suzuki-Miyaura reactions of aryl iodides carried out in a two-chamber reaction vessel gave good to excellent yields of carbonylated products.
- Payne, China M.,Cho, Kyulee,Larsen, David S.
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p. 30736 - 30740
(2019/10/19)
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- A Cyanide-Free Synthesis of Acylcyanides through Ru-Catalyzed C(sp3)-H-Oxidation of Benzylic Nitriles
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A practical method for generation of acylcyanides devoid of any external cyanide sources is presented that relies on a mild Ru-catalyzed selective C?H-oxidation of benzylic nitriles. The starting materials are smoothly generated through condensation of the corresponding carboxylic acid amides using silanes. The obtained acylcyanides can be employed in a plethora of transformation as exemplified to some larger extend in the sequence of C?H-oxidation-Tischenko-rearrangement for the generation of structurally diverse benzoyloxycyanohydrines.
- Eisele, Pascal,Bauder, Michael,Hsu, Shih-Fan,Plietker, Bernd
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p. 689 - 691
(2019/05/07)
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- Tert -Butyl nitrite promoted transamidation of secondary amides under metal and catalyst free conditions
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A mild and efficient method is demonstrated for the transamidation of secondary amides with various amines including primary, secondary, cyclic and acyclic amines in the presence of tert-butyl nitrite. The reaction proceeds through the N-nitrosamide intermediate and provides the transamidation products in good to excellent yields at room temperature. Moreover, the developed methodology does not require any catalyst or additives.
- Sureshbabu, Popuri,Azeez, Sadaf,Chaudhary, Priyanka,Kandasamy, Jeyakumar
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p. 845 - 850
(2019/01/30)
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- Broadly Applicable Ytterbium-Catalyzed Esterification, Hydrolysis, and Amidation of Imides
-
An efficient, broadly applicable, operationally simple, and divergent process for the transformation of imides into a range of carboxylic acid derivatives under mild conditions is reported. By simply using catalytic amounts of ytterbium(III) triflate as a Lewis acid promoter in the presence of alcohols, water, amines, or N,O-dimethylhydroxylamine, a broad range of imides is smoothly and readily converted to the corresponding esters, carboxylic acids, amides, and Weinreb amides in good yields. This method notably enables an easy cleavage of oxazolidinone-based auxiliaries.
- Guissart, Céline,Barros, Andre,Rosa Barata, Luis,Evano, Gwilherm
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supporting information
p. 5098 - 5102
(2018/09/13)
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- Towards a sustainable synthesis of amides: chemoselective palladium-catalysed aminocarbonylation of aryl iodides in deep eutectic solvents
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A palladium-catalysed aminocarbonylation of (hetero)aryl iodides has, for the first time, been accomplished in deep eutectic solvents as environmentally benign and recyclable media, under mild conditions. The reactions proceeded with a good substrate scope, and a variety of amides have been synthesized in yields up to 98%.
- Messa, Francesco,Perrone, Serena,Capua, Martina,Tolomeo, Francesco,Troisi, Luigino,Capriati, Vito,Salomone, Antonio
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supporting information
p. 8100 - 8103
(2018/07/29)
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- Integration of co2 reduction with subsequent carbonylation: Towards extending chemical utilization of co2
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Currently, it still remains a challenge to amplify the spectrum of chemical fixation of CO2, although enormous progress has been achieved in this field. In view of the widespread applications of CO in a myriad of industrial carbonylation processes, an alternative strategy is proposed in which CO2 reduction to CO is combined with carbonylation with CO generated ex situ, which affords efficiently pharmaceutically and agrochemically attractive molecules. As such, CO2 in this study was efficiently reduced by triphenysilane using CsF to CO in a sealed two-chamber reactor. Subsequently, palladium-catalyzed aminocar-bonylation, carbonylative Sonogashira coupling of aryl iodides, and rhodium(I)-mediated Pauson–Khand-type reaction proceeded smoothly to yield amides, alkynones, and bicyclic cy-clopentenones, respectively. Furthermore, the formed alkynones can further be successfully converted to a series of heterocycles, for example, pyrazoles, 3a-hydroxyisoxazolo[3,2-a]isoindol-8-(3aH)-one derivatives and pyrimidines in moderate yields. The striking features of this protocol include operational simplicity, high efficiency, and relatively broad application scope, which represents an alternative avenue for CO2 transformation.
- Lang, Xian-Dong,He, Liang-Nian
-
-
- Metal-Free Thermal Activation of Molecular Oxygen Enabled Direct α-CH2-Oxygenation of Free Amines
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Direct oxidation of α-CH2 group of free amines is hard to achieve due to the higher reactivity of amine moiety. Therefore, oxidation of amines involves the use of sophisticated metallic reagents/catalyst in the presence or absence of hazardous oxidants under sensitive reaction conditions. A novel method for direct C-H oxygenation of aliphatic amines through a metal-free activation of molecular oxygen has been developed. Both activated and unactivated free amines were oxygenated efficiently to provide a wide variety of amides (primary, secondary) and lactams under operationally simple conditions without the aid of metallic reagents and toxic oxidants. The method has been applied to the synthesis of highly functionalized amide-containing medicinal drugs, such as O-Me-alibendol and -buclosamide.
- Ghosh, Santanu,Jana, Chandan K.
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p. 260 - 266
(2018/02/19)
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- Preparation method of aryl amide compound and purification method thereof
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The invention discloses a preparation method for synthesis of an aryl amide compound and a purification method. The preparation method comprises the following steps: various aryl iodides and alkyl primary amine, alkyl secondary amine or alkyl tertiary ami
- -
-
Paragraph 0020; 0023
(2017/05/02)
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- Highly selective acylation of polyamines and aminoglycosides by 5-acyl-5-phenyl-1,5-dihydro-4: H -pyrazol-4-ones
-
5-Acyl-5-phenyl-1,5-dihydro-4H-pyrazol-4-ones, accessible from arylpropargyl phenyldiazoacetates, are highly selective acyl transfer reagents for di- and polyamines, as well as aminoalcohols and aminothiols. As reagents with a carbon-based leaving group, they have been applied for benzoyl transfer with a broad selection of substrates containing aliphatic amino in combination with other competing nucleophilic functional groups. The substrate scope and levels of selectivity for direct benzoyl transfer exceed those of known benzoylating reagents. With exceptional selectivity for acylation between primary amines bound to primary and secondary carbons, these new reagents have been used in direct site-selective monobenzoylation of aminoglycoside antibiotics.
- Marichev, Kostiantyn O.,Garcia, Estevan C.,Bhowmick, Kartick C.,Wherritt, Daniel J.,Arman, Hadi,Doyle, Michael P.
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p. 7152 - 7159
(2017/10/05)
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- Green and environment-friendly method for synthesizing amide bonds
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The invention provides a green and environment-friendly method for synthesizing amide bonds. The green and environment-friendly method includes forming C-Pd bonds from aryl hydrazine compounds under the oxidation effects of oxygen by the aid of palladium catalysts by means of oxidation hydrazine removal; carrying out carbonyl insertion reaction on the C-Pd bonds and carbon monoxide gas to generate palladium acyl species; feeding primary or secondary amine into palladium acyl and then carrying out reductive elimination to obtain a final product amide. The primary or secondary amine is used as a nucleophilic reagent. The green and environment-friendly method has the advantages that palladium catalytic carboamidation reaction is carried out on the aryl hydrazine compounds, normal-pressure CO is used as a carbonyl source for synthesizing the amide, and byproducts are nitrogen and water which are environmentally friendly; the green and environment-friendly method is novel and environmentally friendly, is high in efficiency and has great potential application value.
- -
-
Paragraph 0064; 0065; 0066; 0067; 0068; 0069; 0070-0072
(2017/07/01)
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- Room Temperature Carbonylation of (Hetero) Aryl Pentafluorobenzenesulfonates and Triflates using Palladium-Cobalt Bimetallic Catalyst: Dual Role of Cobalt Carbonyl
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An efficient method for the carbonylation of (hetero) aryl pentafluorobenzenesulfonates and triflates under exceptionally mild conditions using palladium/dicobalt octacarbonyl [Pd/Co2(CO)8] has been developed. Besides acting as carbon monoxide (CO) source, Co2(CO)8enhances the reaction rate by accelerating the CO insertion through an in situ generated bimetallic palladium cobalt tetracarbonyl [Pd-Co(CO)4] complex. Under the optimized reaction condition, carbonylation of a wide range of activated and deactivated, as well as sterically hindered and heteroaromatic, substrates proceeded efficiently at room temperature. The high chemoselectivity and improved synthesis of biologically relevant Isoguvacine and Lazabemide intermediates highlights its scope as a valuable synthetic method. The generality of this protocol was further extended to other electrophiles (bromides, chlorides and tosylates). (Figure presented.).
- Joseph, Jayan T.,Sajith, Ayyiliath M.,Ningegowda, Revanna C.,Shashikanth, Sheena
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supporting information
p. 419 - 425
(2017/02/10)
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- Palladium-Catalyzed Oxidative Carbonylation of Aryl Hydrazines with CO and O2 at Atmospheric Pressure
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Palladium-catalyzed aerobic oxidative aminocarbonylation and alkoxycarbonylation reactions with aryl hydrazines as coupling partners have been developed. The oxidative carbonylation of aryl hydrazines proceeded smoothly at atmospheric pressure CO, employi
- Tu, Yongliang,Yuan, Lin,Wang, Tao,Wang, Changliu,Ke, Jiamei,Zhao, Junfeng
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p. 4970 - 4976
(2017/05/12)
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- Practical Synthesis of Amides via Copper/ABNO-Catalyzed Aerobic Oxidative Coupling of Alcohols and Amines
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A modular Cu/ABNO catalyst system has been identified that enables efficient aerobic oxidative coupling of alcohols and amines to amides. All four permutations of benzylic/aliphatic alcohols and primary/secondary amines are viable in this reaction, enabling broad access to secondary and tertiary amides. The reactions exhibit excellent functional group compatibility and are complete within 30 min-3 h at rt. All components of the catalyst system are commercially available.
- Zultanski, Susan L.,Zhao, Jingyi,Stahl, Shannon S.
-
supporting information
p. 6416 - 6419
(2016/06/09)
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- A microwave-assisted highly practical chemoselective esterification and amidation of carboxylic acids
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The ubiquitousness of esters and amide functionalities makes their coupling reaction one of the most sought-after organic transformations. Herein, we have described an efficient microwave-assisted synthesis of esters and amides. Soluble triphenylphosphine, in conjugation with molecular iodine, gave the desired products without the requirement for a base/catalyst. In addition, a solid-phase synthetic route is incorporated for the said conversion, which has added advantages over solution-phase pathways, such as low moisture sensitivity, easy handling, isolation of the product by simple filtration, and reusability. In short, our method is simple, mild, green, and highly chemoselective in nature.
- Pathak, Gunindra,Das, Diparjun,Rokhum, Lalthazuala
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p. 93729 - 93740
(2016/10/21)
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- Thermolysis of 2-diazo-3-aryl ketoesters: New route to α-aryl malonates and aromatic esters
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Thermochemical excitation enabled efficient α-aryl malonates synthesis from 2-diazo-3-aryl ketoesters and alcohols under transition metal-free reaction conditions. Furthermore, an unusual C[sbnd]C bond cleavage and C[sbnd]O/(N) bond formation occurred whe
- Zhang, Zhao,Tang, Mengyao,Zang, Lei,Zou, Liang-Hua,Li, Jie
-
supporting information
p. 5681 - 5684
(2016/11/28)
-
- Environment-friendly amido bond synthesis method
-
The invention discloses an environment-friendly amido bond synthesis method, which comprises the following steps: oxidizing an aryl hydrazine compound with O2 to form a C-Pd bond by taking Pd(OAc)2 as a catalyst and taking PPh3 as a ligand, inserting CO to a carbon-palladium bond to form an acyl palladium species as a carbonyl source, attacking carbonyl palladium by virtue of amine as a nucleophilic reagent, and performing reductive elimination to obtain a final product amide. According to the method, synthesis of the amide from the hydrazine compound is implemented by adopting CO as the carbonyl source by virtue of a carbonyl insertion method, and a byproduct does not comprise excessive pollutants such as haloid acid, so that the potential application value can be better achieved.
- -
-
Paragraph 0043; 0044; 0045; 0046; 0047
(2017/01/02)
-
- Aminofluorene-Mediated Biomimetic Domino Amination-Oxygenation of Aldehydes to Amides
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A conceptually novel biomimetic strategy based on a domino amination-oxygenation reaction was developed for direct amidation of aldehydes under metal-free conditions employing molecular oxygen as the oxidant. 9-Aminofluorene derivatives acted as pyridoxamine-5′-phosphate equivalents for efficient, chemoselective, and operationally simple amine-transfer oxygenation reaction. Unprecedented RNH transfer involving secondary amine to produce secondary amides was achieved. In the presence of 18O2, 18O-amide was formed with excellent (95%) isotopic purity.
- Ghosh, Santanu,Jana, Chandan K.
-
supporting information
p. 5788 - 5791
(2016/11/29)
-
- Radical-mediated divergent cyclization of benzamides toward perfluorinated or cyanated isoquinolinediones
-
A simple and efficient copper-controlled divergent cyclization of benzamides, which leads to perfluorinated or cyanated isoquinolinediones, is developed. In the presence of AIBN, methacryloyl benzamides with perfluoroalkyl iodides undergo cascade radical addition/cyclization to afford perfluoroinated isoquinolinediones as the major product under metal-free conditions, whereas the use of CuI (10 mol%) is able to redirect the cyclization to yield isoquinolinediones bearing an α-cyano quaternary carbon center. The cyclization features controllable divergent synthesis and a broad substrate scope as well as highly practical reaction conditions, thereby making this strategy a highly attractive means to fluorinate or cyanate isoquinolinediones.
- Deng, You-Lin,Tang, Shi,Ding, Guo-Liang,Wang, Ming-Wei,Li, Jie,Li, Zeng-Zeng,Yuan, Li,Sheng, Rui-Long
-
supporting information
p. 9348 - 9353
(2016/10/13)
-
- Double carbonylation of aryl iodides with amines under an atmospheric pressure of carbon monoxide using sulfur-modified Au-supported palladium
-
A double carbonylation of aryl iodides with amines proceeded smoothly under an atmospheric pressure of carbon monoxide by using palladium nanoparticles (Pd NPs) leached from a sulfur-modified Au-supported palladium material (SAPd), producing α-ketoamides in good to excellent yields. This journal is
- Saito, Nozomi,Taniguchi, Takahisa,Hoshiya, Naoyuki,Shuto, Satoshi,Arisawa, Mitsuhiro,Sato, Yoshihiro
-
supporting information
p. 2358 - 2361
(2015/04/22)
-
- Nickel-catalyzed dehydrogenative cross-coupling: Direct transformation of aldehydes into esters and amides
-
By exploring a new mode of nickel-catalyzed cross-coupling, a method to directly transform both aromatic and aliphatic aldehydes into either esters or amides has been developed. The success of this oxidative coupling depends on the appropriate choice of catalyst and organic oxidant, including the use of either α,α,α-trifluoroacetophenone or excess aldehyde. Mechanistic data that supports a catalytic cycle involving oxidative addition into the aldehyde C-H bond is also presented.
- Whittaker, Aaron M.,Dong, Vy M.
-
supporting information
p. 1312 - 1315
(2015/01/30)
-
- N-heterocyclic carbene-catalyzed oxidative amidation of aldehydes with amines
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The N-heterocyclic carbene (NHC)-catalyzed oxidative amidation of aromatic aldehydes with amines in the presence of N-bromosuccinimide (NBS) as an oxidant has been developed for the synthesis of amides. This amidation strategy is tolerant to both the electronic and the steric nature of the aryl aldehydes employed. The present methodology was extended to chiral amino acid derivatives to generate the corresponding amides in good yields and excellent ee values (>98%).
- Alanthadka, Anitha,Maheswari, C. Uma
-
supporting information
p. 1199 - 1203
(2015/04/22)
-
- Direct oxidative amidation between methylarenes and amines in water
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An environmentally friendly direct oxidative amidation between methylarenes and free amines was developed. The aromatic amide could be prepared efficiently from raw chemicals by employing TBHP as a "green" oxidant with co-catalysis of TBAI and FeCl3 in water.
- Wang, Tao,Yuan, Lin,Zhao, Zhenguang,Shao, Ailong,Gao, Meng,Huang, Yangfei,Xiong, Fei,Zhang, Huali,Zhao, Junfeng
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supporting information
p. 2741 - 2744
(2015/05/27)
-
- Iron-catalyzed direct synthesis of amides from methylarenes
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An efficient, green and first catalytic process has been developed for the direct synthesis of amides from readily available petroleum by-products (methylarenes) and amines using an iron catalyst. In this new catalytic reaction, the methyl group of the me
- Srinivas Kotha, Surya,Badigenchala, Sindhura,Sekar, Govindasamy
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p. 1437 - 1445
(2015/05/19)
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- A novel Pd-catalyzed N-dealkylative carbonylation of tertiary amines for the preparation of amides
-
A novel and convenient protocol for the formation of amides via palladium-catalyzed N-dealkylative carbonylation of alkyl tertiary amines has been developed. In the presence of PdCl2(PhCN)2, CuO, PhCN and CO, a range of substituents on both aryl iodides and alkyl tertiary amines were compatible with the reaction to afford a series of N,N-disubstituted amides in moderate to excellent yields. This journal is
- Fang, Tao,Gao, Xu-Hong,Tang, Ri-Yuan,Zhang, Xing-Guo,Deng, Chen-Liang
-
supporting information
p. 14775 - 14777
(2014/12/11)
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- Expedient carbonylation of aryl halides in aqueous or neat condition
-
An expedient and versatile, microwave-assisted procedure for the carbonylation of aryl halides with boronic acids, alcohols or amines in water or under neat conditions has been developed. The reaction is catalyzed by fluorous, oxime-based palladacycle 1 that shows an excellent recyclable property and low levels of Pd leaching. To demonstrate the usefulness of the protocol, we applied it to the preparation of compounds of pharmaceutical interest, including a precursor of the reverse transcriptase inhibitor, niacin, benzocaine and butamben.
- Ang, Wei Jie,Lo, Lee-Chiang,Lam, Yulin
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p. 8545 - 8558
(2014/12/11)
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- The First ZnII-Catalyzed Oxidative Amidation of Benzyl Alcohols with Amines under Solvent-Free Conditions
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The first zinc-catalyzed oxidative amidation of benzyl alcohols has been developed. Both aliphatic and aromatic amines can be tolerated and applied in this reaction. Various amides were prepared in good yields under solvent-free and mild conditions. Copyright
- Wu, Xiao-Feng,Sharif, Muhammad,Pews-Davtyan, Anahit,Langer, Peter,Ayub, Khurshid,Beller, Matthias
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supporting information
p. 2783 - 2787
(2013/06/26)
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- A phosphine-free Pd catalyst for the selective double carbonylation of aryl iodides
-
The first phosphine-free Pd-catalysed double carbonylation of aryl iodides is reported as a general and practical method, giving excellent conversions and selectivities for a wide range of aryl iodides and amine nucleophiles under atmospheric CO pressure. The Royal Society of Chemistry 2012.
- De La Fuente, Veronica,Godard, Cyril,Zangrando, Ennio,Claver, Carmen,Castillon, Sergio
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supporting information; experimental part
p. 1695 - 1697
(2012/03/22)
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- Aminocarbonylations employing Mo(CO)6 and a bridged two-vial system: Allowing the use of nitro group substituted aryl iodides and aryl bromides
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A bridged two-vial system aminocarbonylation protocol where Mo(CO) 6 functions as an external in situ solid source of CO has been developed. For the first time both nitro group containing aryl/heteroaryl iodides and bromides gave good to excellent yields in the Mo(CO) 6-mediated and palladium(0)-catalyzed conversion to benzamides, while the identical one-vessel protocol afforded extensive reduction of the nitro functionality. The above-mentioned bridged two-compartment protocol furnished good results with both primary amines and secondary amines and sluggish aniline nucleophiles at 65-85 C reaction temperatures.
- Nordeman, Patrik,Odell, Luke R.,Larhed, Mats
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p. 11393 - 11398
(2013/02/23)
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- Highly selective palladium-catalysed aminocarbonylation of aryl iodides using a bulky diphosphine ligand
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An efficient methodology for the synthesis of amides via palladium-catalysed aminocarbonylation of aryl iodides is reported using the bulky cis-1,2-bis[(di-tert-butylphosphino)methyl]cyclohexane ligand under atmospheric pressure of carbon monoxide. Excellent conversions (up to 99%) and chemoselectivities (up to 99%) were obtained for a range of aryl iodides and amine nucleophiles. The effect of the substituents on the substrate and nucleophiles on the catalytic performance was investigated. An NMR study was also carried out and key intermediates of the catalytic cycle were detected and characterised. Copyright
- De La Fuente, Veronica,Godard, Cyril,Claver, Carmen,Castillon, Sergio
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experimental part
p. 1971 - 1979
(2012/09/22)
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- Rhodium(iii)-catalyzed oxidative carbonylation of benzamides with carbon monoxide
-
An efficient strategy for the oxidative carbonylation of aromatic amides via C-H/N-H activation to form phthalimides using an Rh(iii) catalyst has been developed. The reaction shows a preference for C-H bonds of electron-rich aromatic amides and tolerates a variety of functional groups. The Royal Society of Chemistry 2011.
- Du, Ya,Hyster, Todd K.,Rovis, Tomislav
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p. 12074 - 12076
(2011/12/14)
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- Formal nucleophilic substitution of bromocyclopropanes with amides en route to conformationally constrained β-amino acid derivatives
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A chemo- and diastereoselective protocol for the formal nucleophilic substitution of 2-bromocyclopropylcarboxamides with secondary amides is described. This method allows for convergent and highly selective synthesis of trans-β-aminocyclopropane carboxylic acid derivatives.
- Prosser, Anthony R.,Banning, Joseph E.,Rubina, Marina,Rubin, Michael
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supporting information; experimental part
p. 3968 - 3971
(2010/11/02)
-
- Sintered silicon carbide: A new ceramic vessel material for microwave chemistry in single-mode reactors
-
Silicon carbide (SiC) is a strongly microwave absorbing chemically inert ceramic material that can be utilized at extremely high temperatures due to its high melting point and very low thermal expansion coefficient. Microwave irradiation induces a flow of electrons in the semiconducting ceramic that heats the material very efficiently through resistance heating mechanisms. The use of SiC carbide reaction vessels in combination with a single-mode microwave reactor provides an almost complete shielding of the contents inside from the electromagnetic field. Therefore, such experiments do not involve electromagnetic field effects on the chemistry, since the semiconducting ceramic vial effectively prevents microwave irradiation from penetrating the reaction mixture. The involvement of electromagnetic field effects (specific/nonthermal microwave effects) on 21 selected chemical transformations was evaluated by comparing the results obtained in microwave-transparent Pyrex vials with experiments performed in SiC vials at the same reaction temperature. For most of the 21 reactions, the outcome in terms of conversion/purity/product yields using the two different vial types was virtually identical, indicating that the electromagnetic field had no direct influence on the reaction pathway. Due to the high chemical resistance of SiC, reactions involving corrosive reagents can be performed without degradation of the vessel material. Examples include high-temperature fluorine-chlorine exchange reactions using triethylamine trihydrofluoride, and the hydrolysis of nitriles with aqueous potassium hydroxide. The unique combination of high microwave absorptivity, thermal conductivity, and effusivity on the one hand, and excellent temperature, pressure and corrosion resistance on the other hand, makes this material ideal for the fabrication of reaction vessels for use in microwave reactors. Simulating conductive heat transfer in a microwave: Using reaction vials made out of strongly microwave-absorbing silicon carbide (SiC) in a microwave reactor simulates a conductively heated autoclave experiment due to efficient shielding of the electromagnetic field by the SiC vial. Advantages of SiC vials for microwave processing include their excellent corrosion resistance, thermal stability, and high thermal effusivity and conductivity.
- Gutmann, Bernhard,Obermayer, David,Reichart, Benedikt,Prekodravac, Bojana,Irfan, Muhammad,Kremsner, Jennifer M.,Kappe, C. Oliver
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supporting information; experimental part
p. 12182 - 12194
(2011/02/23)
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- 5H-3-oxa-Octafluoropentanesulfonyl fluoride: a novel and efficient condensing agent for esterification, amidation and anhydridization
-
The use of 5H-3-oxa-octafluoropentanesulfonyl fluoride (HCF2CF2OCF2CF2SO2F) as a novel and efficient condensing reagent for esterification of carboxylic acids with alcohols and amidation of carboxylic acids with amines in the presence of 1,3-diazabicyclo[5.4.0]-undec-7-ene (DBU) is reported. HCF2CF2OCF2CF2SO2F cannot serve as a condensing agent for anhydridization of carboxylic acids, however, HCF2CF2OCF2CF2SO2F/(CH3)3SiCN system can mediate anhydridization of some aromatic carboxylic acids.
- Yan, Zhaohua,Tian, Weisheng,Zeng, Fanrong,Dai, Yanfeng
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experimental part
p. 2727 - 2729
(2009/09/06)
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- Microwave chemistry in silicon carbide reaction vials: Separating thermal from nonthermal effects
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Running oil-bath chemistry in a microwave! Using reaction vials made out of strongly microwave-absorbing silicon carbide (SiC) in a microwave reactor simulates experiments conducted in an autoclave with conductive heating because of the efficient shielding of the electromagnetic field by the SiC vial. This technology makes it possible to study the significance of microwave effects.
- Obermayer, David,Gutmann, Bernhard,Oliver Kappe
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supporting information; scheme or table
p. 8321 - 8324
(2010/01/06)
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- Oxidative amidation of aldehydes and alcohols with primary amines catalyzed by KI-TBHP
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Oxidative amidation of aldehydes and alcohols with amines to afford the corresponding amides in excellent yields and ee values over 98% is achieved by using a catalytic amount of KI in combination with TBHP as the external oxidant. This method avoids the use of expensive and/or air-sensitive reagents. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Rajender Reddy,Uma Maheswari,Venkateshwar,Lakshmi Kantam
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supporting information; experimental part
p. 3619 - 3622
(2009/05/07)
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- Pd-catalyzed oxidative amidation of aldehydes with hydrogen peroxide
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Using hydrogen peroxide as a key oxidant, catalytic oxidative amidation between aldehydes and amines was effectively carried out with PdCl2-xantophos as a catalyst in methanol under acidic conditions. The new protocol is mechanistically different from the previous one through β-hydride elimination.
- Suto, Yutaka,Yamagiwa, Noriyuki,Torisawa, Yasuhiro
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p. 5732 - 5735
(2008/12/22)
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- Microwave-enhanced aminocarbonylations in water
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(Chemical Equation Presented) Aryl bromides can be rapidly converted to the corresponding secondary and tertiary benzamides in water. By using Mo(CO) 6 as the source of carbon monoxide, aminocarbonylations were conducted under air after only 10
- Wu, Xiongyu,Larhed, Mats
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p. 3327 - 3329
(2007/10/03)
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- Kinetics and Mechanisms of the Aminolysis of N-Hydroxysuccinimide Esters in Aqueous Buffers
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Rate constants for the aminolysis of the N-hydroxysuccinimide (NHS) ester of p-methoxybenzoic acid, in aqueous buffer systems (20percent dioxane), have been determined under pseudo-first-order conditions.For the amines studied (pKa = 7.60-11.1), the data fit the rate expression kobsd - kOH--> = k1free.This rate equation is in contrast to the two-term rate equation (kobsd = k1 + k22) obtained for this reaction in anhydrous dioxane (Cline, G.W.; Hanna, S.B.J.Am.Chem.Soc 1987, 109, 3087) and is suggestive of a disproportionate decrease in the catalyzed vs the uncatalyzed reaction path upon changing from a nonaqueous to an aqueous solvent system.The correlation of amine basicity with the nucleophilic rate constant, k1, yields a slope βnuc = 1.0.The magnitude of βnuc, in terms of a reaction mechanism where a tetrahedral intermediate is formed in a fast preequilibrium followed by rate-determining breakdown to products, reflects the sensitivity to changes in charge accumulation in the formation of the tetrahedral intermediate.The resultant increased rate constants, with increased basicity, are due to the effect of an increased concentration of the tetrahedral intermediate.A qualitative evaluation of the literature and current data concerning the leaving ability of N-hydroxy esters, in comparison to phenyl esters (equivalent acyl groups and nucleophiles), reveals that, with leaving groups of comparable basicity, the nucleophilic rate constants for N-hydroxy esters are about 2 orders of magnitude greater than that for phenyl esters.
- Cline, Gary W.,Hanna, Samir B.
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p. 3583 - 3586
(2007/10/02)
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- One-electron Oxidation of Closed-shell Molecules. Part 4. Acid-induced Oxidative Cleavage of Substituted 1,2,2,2-Tetraphenylethanones (Benzpinacolones) with Diaroyl Peroxides
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The acid-induced oxidative cleavage of anispinacolone with diaroyl peroxides in 1,2-dichloroethane-trifluoroacetic acid (TFA) has been investigated.The principal two products after work-up are tris-(p-methoxyphenyl)methanol and p-methoxybenzoic acid; the latter was found as anhydrides in the reaction mixture.Free-radical formation in the course of the cleavage was verified by polymerization of added acrylonitrile in the oxidation by bis-(3,5-dinitrobenzoyl) peroxide.When the oxidation of anispinacolone (90percent (13)C) by dibenzoyl peroxide was carried out in a (13)C n.m.r. probe, an emission peak, assigned to p-methoxybenzoic trifluoroacetic anhydride, was observed.The logarithms of the rate constants for oxidation of p-substituted benzpinacolones by dibenzoyl peroxide were linearly correlated with the oxidation potentials of the benzpinacolones.These results are consistent with a single-electron transfer (s.e.t.) pathway from benzpinacolones to dibenzoyl peroxide.The oxidation is first-order in each reactant and is promoted by TFA.The effect of TFA is accounted for by two factors, (i) assisted O-O bond cleavage of the peroxide radical anion by TFA, and (ii) the formation of protonated peroxide, a more powerful oxidizing species.The former factor is dominant at lower TFA concentrations ( 0.05 M), the latter at higher concentrations.
- Kitagawa, Toshikazu,Takeuchi, Ken'ichi,Murai, Osamu,Matsui, Shin,Inoue, Takeshi,Nishimura, Makoto et al.
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p. 1987 - 1996
(2007/10/02)
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- Kinetics and Mechanism of Aminolysis of Carbamates
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The kinetics of the n-butylaminolysis of three series of mono- and disubstituted phenyl N-phenylcarbamates 1-3 have been studied spectrophotometrically under pseudo-first-order conditions in dioxane.The relation kobsd = k2 + k32 was found applicable for all esters.The rate constants k2 and k3 were correlated by the Hammett equation, and the corresponding activation parameters were determined.The reaction was found to be much more sensitive to a substituent on the leaving group (OAr) than to a substitutent on the amine portion (NHAr) of the esters.Results from crossover experiments revealed the absence of isocyanate intermediate.The mechanism of the aminolysis of carbamates is discussed in terms of these facts.
- Shawali, Ahmad S.,Harhash, Abdelhamid,Sidky, Mohmoud M.,Hassaneen, Hamdi M.,Elkaabi, Sherifa S.
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p. 3498 - 3501
(2007/10/02)
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- One-electron Oxidation of Closed-shell Molecules. Part 3. Oxidative Cleavage of 1,2,2,2-Tetrakis-(p-methoxyphenyl)ethanone with Dibenzoyl and Bis(3,5-dinitrobenzoyl) Peroxides: Mechanistic Changeover of the Peroxide Function from Radical to Molecular Oxidation
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1,2,2,2-Tetrakis-(p-methoxyphenyl)ethanone (anispinacolone) (1) is cleaved by dibenzoyl peroxide (2) or bis-(3,5-dinitrobenzoyl) peroxide (3), affording tris-(p-methoxyphenyl)methyl benzoate (or 3,5-dinitrobenzoate) and benzoic (or 3,5-dinitrobenzoic) p-methoxybenzoic anhydride as the principal cleavage products. 13C N.m.r.CIDNP studies by use of labelled anispinacolone (An3*C-*COAn ; *C 90percent 13C) indicated that p-methoxybenzoyl radical is formed, presumably by way of the radical cation +. which is produced by a single-electron transfer (s.e.t.) mechanism.The formation of the p-methoxybenzoyl radical was also indicated by spin-trapping experiments.The decomposition rates of (2) at 50.0 deg C are unaltered on addition of (1) in nonpolar solvents such as dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, and benzene, whereas those of (3) are markedly accelerated.The cleavage of (1) by (2) is supressed by added 3,4-dichlorostyrene by a factor of 6.7, whereas that of (1) by (3) is almost unaffected.These results suggest that in the case of dibenzoyl peroxide (2) the thermally produced benzoyloxyl radical works as a one-electron acceptor (or oxidant) upon (1), whereas when bis-(3,5-dinitrobenzoyl) peroxide (3) is used the peroxide molecule oxidizes (1), probably by way of an s.e.t. mechanism even in such nonpolar solvents.On the other hand, in polar solvents such as (CF3)2CHOH, teramethylene sulphone, and acetonitrile the decomposition of (2) is accelerated by added anispinacolone, suggesting that the intermolecular s.e.t. reaction is partially involved in such polar solvents.Consequently, the oxidative cleavage of anispinacolone (1) by diaroyl peroxides provides the first example of dichotomy in the s.e.t. reaction of diaroyl peroxides, which can be considered a counterpart of the SN1-SN2 dichotomy in nucleophilic substitution, as far as the molecularity of the peroxide is concerned.
- Takeuchi, Ken'ichi,Murai, Osamu,Matsui, Shin,Inoue, Takeshi,Kitagawa, Toshikazu,Okamoto, Kunio
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p. 1301 - 1310
(2007/10/02)
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