6318-51-0Relevant academic research and scientific papers
Overcoming Electron-Withdrawing and Product-Inhibition Effects by Organocatalytic Aerobic Oxidation of Alkylpyridines and Related Alkylheteroarenes to Ketones
Wang, Hua,Liu, Jie,Qu, Jian-Ping,Kang, Yan-Biao
, p. 3942 - 3948 (2020/03/23)
An organocatalyzed aerobic benzylic C-H oxidation of alkyl and aryl heterocycles has been developed. This transition metal-free method is able to overcome the electron-withdrawing effect as well as product-inhibition effects in heterobenzylic radical oxidation. A variety of ketones bearing N-heterocyclic groups could be prepared under relatively mild conditions with moderate to high yields.
Rapid formation of nitrogen-doped carbon foams by self-foaming as metal-free catalysts for selective oxidation of aromatic alkanes
Qin, Guo-Xin,Hao, Yan,Wang, Shuai,Dong, Yu-Bin
, (2020/01/03)
Porous carbon materials have attracted considerable interest as metal-free catalysts. In this study, we report a nitrogen-doped and nanofiber-based porous carbon foam produced via an efficient and facile self-foaming approach and its subsequent pyrolysis; in this approach, carbon dioxide-rich ethanolamine serves as the foaming agent, N source and polymerization catalyst. Meanwhile resorcinol and formaldehyde are used as carbon sources. Carbon dioxide-rich ethanolamine plays a crucial role in the release of gas as well as initiating polymerization on the interfaces of bubbles, which directs the formation of polymer foam. The N-doped carbon foam can be a highly active metal-free heterogeneous catalyst to promote selective oxidation of the benzyl group to the corresponding phenone. In addition, the carbon foams are easily cast with different morphologies. Notably, the prepared carbon foam is fabricated as a monolithic reactor for the oxidation reaction, which also exhibits good catalytic performances in the scale-up experiment.
Iron-catalyzed oxidative functionalization of C(sp3)-H bonds under bromide-synergized mild conditions
Yu, Han,Zhao, Qixin,Wei, Zheyu,Wu, Zhikang,Li, Qi,Han, Sheng,Wei, Yongge
supporting information, p. 7840 - 7843 (2019/07/12)
An efficient oxidation and functionalization of C-H bonds with an inorganic-ligand supported iron catalyst and hydrogen peroxide to prepare the corresponding ketones was achieved using the bromide ion as a promoter. Preliminary mechanistic investigations indicated that the bromide ion can bind to FeMo6 to form a supramolecular species (FeMo6·2Br), which can effectively catalyze the reaction.
Method for simply and conveniently synthesizing heterocyclic aryl ketone compound
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Paragraph 0034; 0035; 0036, (2019/01/23)
The invention discloses a method for simply and conveniently synthesizing a heterocyclic aryl ketone compound, and belongs to the technical field of the organic chemistry. The method comprises the following steps: using a benzyl heterocyclic compound as a reaction raw material, in a polar solvent, heating and reacting in an oxygen atmosphere, to obtain a multi-substituted ketone compound. The method is capable of using molecular oxygen as an oxidizing agent, green and environmental, and capable of preparing ketone by directly promoting selective oxidation and functionalization of a Csp3-H bond, and broadening a synthetic method for the ketone compound.
A convenient and practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with formic acid as carbon monoxide source
You, Shengyong,Yan, Chenyu,Zhang, Rongli,Cai, Mingzhong
, (2019/01/04)
A practical heterogeneous palladium-catalyzed carbonylative Suzuki coupling of aryl iodides with arylboronic acids under carbon monoxide gas-free conditions has been developed using a bidentate phosphino-functionalized magnetic nanoparticle-immobilized palladium(II) complex as catalyst. Formic acid was utilized as the carbon monoxide source with dicyclohexylcarbodiimide as the activator, and a wide variety of biaryl ketones were generated in moderate to high yields. The new heterogeneous palladium catalyst can be prepared via a simple procedure and can easily be separated from a reaction mixture by simply applying an external magnet and recycled up to 10 times without any loss of activity.
Metal-Free Halogen(I) Catalysts for the Oxidation of Aryl(heteroaryl)methanes to Ketones or Esters: Selectivity Control by Halogen Bonding
Guha, Somraj,Sekar, Govindasamy
supporting information, p. 14171 - 14182 (2018/09/10)
Metal-free halogen(I) catalysts were used for the selective oxidation of aryl(heteroaryl)methanes [C(sp3)?H] to ketones [C(sp2)=O] or esters [C(sp3)?O]. The synthesis of ketones was performed with a catalytic amount of NBS in DMSO solvent. Experimental studies and density functional theory (DFT) calculations supported the formation of halogen bonding (XB) between the heteroarene and N-bromosuccinimide, which enabled imine–enamine tautomerism of the substrates. No additional activator was required for this crucial step. Isotope-labeling and other supporting experiments suggested that a Kornblum-type oxidation with DMSO and aerobic oxygenation with molecular oxygen took place simultaneously. A background XB-assisted electron transfer between the heteroarenes and halogen(I) catalysts was responsible for the formation of heterobenzylic radicals and, thus, the aerobic oxygenation. For selective acyloxylation (ester formation), a catalytic amount of iodine was employed with tert-butyl hydroperoxide in aliphatic carboxylic acid solvent. Several control reactions, spectroscopic studies, and Time-Dependent Density Functional Theory (TD–DFT) calculations established the presence of acetyl hypoiodite as an active halogen(I) species in the acetoxylation process. With the help of a selectivity study, for the first time we report that the strength of the XB interaction and the frontier orbital mixing between the substrates and acyl hypoiodites determined the extent of the background electron-transfer process and, thus, the selectivity of the reaction.
Room Temperature Metal-Catalyzed Oxidative Acylation of Electron-Deficient Heteroarenes with Alkynes, Its Mechanism, and Application Studies
Sharma, Shweta,Kumar, Mukesh,Vishwakarma, Ram A.,Verma, Mahendra K.,Singh, Parvinder Pal
, p. 12420 - 12431 (2018/10/20)
Herein, we report an original one-step, simple, room-temperature, regioselective Minisci reaction for the acylation of electron-deficient heteroarenes with alkynes. The method has broad functional group compatibility and gives exclusively monoacylated products in good to excellent yields. The mechanistic pathway was analyzed based on a series of experiments confirming the involvement of a radical pathway. The 18O-labeling experiment suggested that water is a source of oxygen in the acylated product, and head space GC-MS experiment shows the C-C cleavage occurs via release as CO2.
Efficient Selenium-Catalyzed Selective C(sp3)?H Oxidation of Benzylpyridines with Molecular Oxygen
Jin, Weiwei,Zheng, Poonnapa,Wong, Wing-Tak,Law, Ga-Lai
supporting information, p. 1588 - 1593 (2017/05/05)
An efficient selenium-catalyzed direct oxidation of benzylpyridines in aqueous DMSO has been successfully developed by using molecular oxygen as the oxidant. A variety of benzoylpyridines with broad functional group tolerance were obtained in modest to excellent yields and with exclusive chemoselectivity. (Figure presented.).
Copper-Catalyzed Aerobic Oxygenation of Benzylpyridine N-Oxides and Subsequent Post-Functionalization
Sterckx, Hans,Sambiagio, Carlo,Médran-Navarrete, Vincent,Maes, Bert U. W.
, p. 3226 - 3236 (2017/09/13)
A copper-catalyzed aerobic oxidation of benzylpyridine N-oxides is reported. The N-oxide moiety acts as a built-in activator for the benzylic methylene oxidation, without requirement of additives. Reaction conditions were identified which suppress undesired benzoylpyridine formation via N-deoxygenation involving intermolecular oxygen transfer. The versatility of the N-oxide group of the benzoylpyridine N-oxide reaction products for post-functionalization of the pyridine ring is demonstrated through efficient C–C, C–N, C–O and C–Cl bond forming procedures, with both nucleophiles and electrophiles. Finally, the applicability of the new synthetic methodology is demonstrated in an alternative route towards the antihistaminic drug Acrivastine via three consecutive N-oxide activated C–H functionalization processes, starting from picoline N-oxide. (Figure presented.).
Method for preparing alpha-(4-chlorphenyl)pyridine-2-methanol
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Paragraph 0007; 0018-0025, (2017/08/31)
The invention discloses a method for preparing alpha-(4-chlorphenyl)pyridine-2-methanol, and relates to the technical field of organic synthesizing. The method comprises the following steps of using 2-cyanopyridine as an initial raw material; generating Grignard reaction with a Grignard reagent of para chlorobromobenzene to generate alpha-(4-chlorphenyl)pyridine-2-methanol; generating reduction reaction with sodium borohydride to obtain the alpha-(4-chlorphenyl)pyridine-2-methanol. The synthesizing method has the advantages that the corrosion of raw materials to production equipment is avoided, the used solvent can be recycled and reutilized, the green chemical concept is met, the hazard of pollution to environment is decreased, and the production cost is reduced; the yield rate and purity of the alpha-(4-chlorphenyl)pyridine-2-methanol are higher, and the total molar yield rate is 70% or above.
