- Amide Bond Formation via Aerobic Photooxidative Coupling of Aldehydes with Amines Catalyzed by a Riboflavin Derivative
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We report an effective, operationally simple, and environmentally friendly system for the synthesis of tertiary amides by the oxidative coupling of aromatic or aliphatic aldehydes with amines mediated by riboflavin tetraacetate (RFTA), an inexpensive organic photocatalyst, and visible light using oxygen as the sole oxidant. The method is based on the oxidative power of an excited flavin catalyst and the relatively low oxidation potential of the hemiaminal formed by amine to aldehyde addition.
- Hassan Tolba, Amal,Krupi?ka, Martin,Chudoba, Josef,Cibulka, Radek
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supporting information
p. 6825 - 6830
(2021/09/11)
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- A Fast and General Route to Ketones from Amides and Organolithium Compounds under Aerobic Conditions: Synthetic and Mechanistic Aspects
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We report that the nucleophilic acyl substitution reaction of aliphatic and (hetero)aromatic amides by organolithium reagents proceeds quickly (20 s reaction time), efficiently, and chemoselectively with a broad substrate scope in the environmentally responsible cyclopentyl methyl ether, at ambient temperature and under air, to provide ketones in up to 93 % yield with an effective suppression of the notorious over-addition reaction. Detailed DFT calculations and NMR investigations support the experimental results. The described methodology was proven to be amenable to scale-up and recyclability protocols. Contrasting classical procedures carried out under inert atmospheres, this work lays the foundation for a profound paradigm shift of the reactivity of carboxylic acid amides with organolithiums, with ketones being straightforwardly obtained by simply combining the reagents under aerobic conditions and with no need of using previously modified or pre-activated amides, as recommended.
- Ghinato, Simone,Territo, Davide,Maranzana, Andrea,Capriati, Vito,Blangetti, Marco,Prandi, Cristina
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supporting information
p. 2868 - 2874
(2021/01/21)
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- Method for preparing amide compound by photocatalysis of nitrogen-containing heterocyclic compound
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The invention provides a method for preparing an amide compound by photocatalysis of a nitrogen-containing heterocyclic compound. The method comprises the following steps: mixing the nitrogen-containing heterocyclic compound, organic carboxylic acid and tetrahalomethane in a solvent, adding a catalyst, and reacting under the illumination condition to prepare the amide compound. According to the invention, the organic carboxylic acid, the nitrogen-containing heterocyclic compound containing reactive hydrogen on nitrogen atoms and the tetrahalomethane are used as raw materials, so the raw materials are wide in source, low in cost and high in safety, and large-scale production is facilitated; the halogen simple substance is co-produced in the reaction process, the added value is high, a large amount of waste is prevented from being generated, and the method has high atom economy and environmental friendliness; light conditions are adopted to replace traditional heating and high-pressure conditions, the reaction conditions are mild, environmental pollution is reduced, and the reaction cost is reduced; the method has the advantages of good substrate applicability, mild process conditions, environmental protection, simple process, simple and feasible operation method, and facilitation of popularization and application.
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Paragraph 0055-0058; 0093; 0094
(2021/06/06)
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- Phenysilane and Silicon Tetraacetate: Versatile Promotors for Amide Synthesis
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Phenylsilane was reevaluated as a useful coupling reagent for amide synthesis. At room temperature, a wide range of amides and peptides were obtained in good to excellent yields (up to 99 %). For the first time, Weinreb amides synthesis mediated by a hydrosilane were also documented. Comparative experiments with various acetoxysilanes suggested the involvement of a phenyl-triacyloxysilane. From this mechanistic study, silicon tetraacetate was shown as an efficient amine acylating agent.
- Morisset, Eléonore,Chardon, Aurélien,Rouden, Jacques,Blanchet, Jér?me
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supporting information
p. 388 - 392
(2020/01/24)
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- Synthesis of Ag/g-C3N4Composite as Highly Efficient Visible-Light Photocatalyst for Oxidative Amidation of Aromatic Aldehydes
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In this contribution, an Ag/g-C3N4nanocomposite was synthesized and utilized as highly efficient and green photocatalyst for organic reactions under visible light irradiation. A layered, porous g-C3N4was synthes
- Wang, Lingling,Yu, Min,Wu, Chaolong,Deng, Nan,Wang, Chao,Yao, Xiaoquan
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p. 2631 - 2641
(2016/08/31)
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- Phenazinium salt-catalyzed aerobic oxidative amidation of aromatic aldehydes
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Amides are prevalent in organic synthesis. Developing an efficient synthesis that avoids expensive oxidants and heating is highly desirable. Here the oxidative amidation of aromatic aldehydes is reported using an inexpensive metal-free visible light photocatalyst, phenazine ethosulfate, at low catalytic loading (1-2 mol %). The reaction proceeds at ambient temperature and uses air as the sole oxidant. The operationally easy procedure provides an economical, green, and mild alternative for the formation of amide bonds.
- Leow, Dasheng
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supporting information
p. 5812 - 5815
(2015/02/19)
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- Metal-free one-pot oxidative amination of aldehydes to amides
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Metal-free oxidative amination of aromatic aldehydes in the presence of TBHP provides convenient access to amides in 85-99% under mild reaction conditions within 5 h. This method avoids free carboxylic acid intermediates and integrates aldehyde oxidation and amide bond formation, which are usually accomplished separately, into a single operation. Proline-derived amides can be prepared in excellent yields without noticeable racemization.
- Ekoue-Kovi, Kekeli,Wolf, Christian
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p. 3429 - 3432
(2008/02/12)
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- Synthesis of 11C-amides using [11C]carbon monoxide and in situ activated amines by palladium-mediated carboxaminations
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[11C]Carbon monoxide at low concentrations, aryl halides and amines were used in the palladium-mediated synthesis of twenty 11C-amides. In the study several approaches to improve the radiochemical yield were explored. Eight of the selected amides were prepared by in situ activation of the amines using lithium bis(trimethylsilyl)amide and the radiochemical yields of these reactions were improved compared to utilising a previous reported method. In the synthesis of 1-[carbonyl-11C]benzoyl-3-methyl-1H-indole (11) from 3-methyl-1H-indole (25), the corresponding organotin-amine was prepared prior to the acylation reaction. In a typical experiment, N-(4-hydroxyphenyl)-[carbonyl-11C]acetamide (5) was prepared in 15% radiochemical yield using 4-aminophenol (20) but the yield increased to 63% when the amine was activated by lithium bis(trimethylsilyl)amide.
- Karimi, Farhad,Langstroem, Bengt
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p. 541 - 546
(2007/10/03)
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- EFFECTIVE MOLARITIES FOR INTRAMOLECULAR HYDRIDE TRANSFER. REDUCTION BY 1,4-DIHYDROPYRIDINES OF THE NEIGHBOURING α-KETOESTER GROUP
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The synthesis is described of several 1,4-dihydronicotinic acid derivatives with side-chain carbonyl groups, attached either to amide nitrogen or the 5-position of the ring.Intramolecular hydride transfer is observed only with activated carbonyl groups: compounds with simple ketones in the side-chain are stable.A minimum effective molarity of 6 M is estimated for hydride transfer to α-ketoester carbonyl by way of six-membered cyclic transition state.It is suggested that the low EM's are likely to be the norm for intramolecular hydride transfer in unstrained systems.
- Kirby, Anthony J.,Walwyn, David R.
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p. 667 - 680
(2007/10/02)
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