- Electrochemical oxidation-induced benzyl C–H carbonylation for the synthesis of aromatic α-diketones
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Electrochemical oxidation-induced direct carbonylation of benzyl C–H bond for the synthesis of aromatic α-diketones is described. In this process, tetrabutylammonium iodide (nBu4NI) not only acts as an electrolyte, but its iodine anion is oxidized to an iodine radical at the anode, acting as a hydrogen atom transfer agent. The iodine radical extracts the benzyl hydrogen atom and causes the carbonylation of the benzyl position, where O2 in the air is used as an oxygen source.
- Tan, Yu-Fang,Chen, Yuan,Li, Rui-Xue,Guan, Zhi,He, Yan-Hong
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- Aerobic oxygenation of α-methylene ketones under visible-light catalysed by a CeNi3complex with a macrocyclic tris(salen)-ligand
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A hetero-tetranuclear CeNi3 complex with a macrocyclic ligand catalysed the aerobic oxygenation of a methylene group adjacent to a carbonyl group under visible-light radiation to produce the corresponding α-diketones. The visible-light induced homolysis of the Ce-O bond of a bis(enolate) intermediate is proposed prior to aerobic oxygenation.
- Fujiwara, Sakiko,Kon, Yoshihiro,Mashima, Kazushi,Nagae, Haruki,Okuda, Jun,Sakamoto, Kazutaka,Sato, Kazuhiko,Schindler, Tobias
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p. 11169 - 11172
(2021/11/04)
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- Visible-Light-Induced Photocatalytic Oxidative Decarboxylation of Cinnamic Acids to 1,2-Diketones
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A concerted metallophotoredox catalysis has been realized for the efficient decarboxylative functionalization of α,β-unsaturated carboxylic acids with aryl iodides in the presence of perylene bisimide dye to afford 1,2-diketones.
- Chand, Shiv,Pandey, Anand Kumar,Singh, Rahul,Singh, Krishna Nand
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p. 6486 - 6493
(2021/05/06)
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- Synthesis of unsymmetrical benzilsviapalladium-catalysed a-arylation-oxidation of 2-hydroxyacetophenones with aryl bromides
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A diverse set of unsymmetrically substituted benzils were facilely synthesised by a cross-coupling reaction between 2-hydroxyacetophenones and aryl bromides in the presence of a palladium catalyst. Experimental studies suggested a reaction mechanism involving a one-pot tandem palladium-catalysed a-arylation and oxidation, where aryl bromides play a dual role as mild oxidants as well as arylating agents.
- Matsuda, Takanori,Oyama, Souta
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supporting information
p. 3679 - 3683
(2020/06/03)
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- A Bifunctional Iron Nanocomposite Catalyst for Efficient Oxidation of Alkenes to Ketones and 1,2-Diketones
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We herein report the fabrication of a bifunctional iron nanocomposite catalyst, in which two catalytically active sites of Fe-Nx and Fe phosphate, as oxidation and Lewis acid sites, were simultaneously integrated into a hierarchical N,P-dual doped porous carbon. As a bifunctional catalyst, it exhibited high efficiency for direct oxidative cleavage of alkenes into ketones or their oxidation into 1,2-diketones with a broad substrate scope and high functional group tolerance using TBHP as the oxidant in water under mild reaction conditions. Furthermore, it could be easily recovered for successive recycling without appreciable loss of activity. Mechanistic studies disclose that the direct oxidation of alkenes proceeds via the formation of an epoxide as intermediate followed by either acid-catalyzed Meinwald rearrangement to give ketones with one carbon shorter or nucleophilic ring-opening to generate 1,2-diketones in a cascade manner. This study not only opens up a fancy pathway in the rational design of Fe-N-C catalysts but also offers a simple and efficient method for accessing industrially important ketones and 1,2-diketones from alkenes in a cost-effective and environmentally benign fashion.
- Ma, Zhiming,Ren, Peng,Song, Tao,Xiao, Jianliang,Yang, Yong,Yuan, Youzhu
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p. 4617 - 4629
(2020/05/19)
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- Ruthenium/dendrimer complex immobilized on silica-functionalized magnetite nanoparticles catalyzed oxidation of stilbenes to benzil derivatives at room temperature
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A new ruthenium/dendrimer complex stabilized on the surface of silica-functionalized nano-magnetite was fabricated and well characterized. The nano-catalyst showed good activity in the synthesis of benzil derivatives via the oxidation of stilbenes with high turnover frequency (TOF) at room temperature. Moreover, the catalyst could also be reused up to fifteen times without any loss of its activity.
- Ghanaatzadeh, Niloofar,Hashemi, Hajar,Moghadam, Majid,Niknam, Khodabakhsh,Saberi, Dariush
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- Magnesium Aldimines Prepared by Addition of Organomagnesium Halides to 2,4,6-Trichlorophenyl Isocyanide: Synthesis of 1,2-Dicarbonyl Derivatives
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The selective addition of organomagnesium reagents to 2,4,6-trichlorophenyl isocyanide leading to magnesiated aldimines is reported. These aldimines react with Weinreb amides, ketones, or carbonates to provide the corresponding carbonyl derivatives after acidic cleavage. This allows for an efficient synthesis of 1,2-dicarbonyl compounds and α-hydroxy ketones.
- Schw?rzer, Kuno,Bellan, Andreas,Z?schg, Maximilian,Karaghiosoff, Konstantin,Knochel, Paul
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supporting information
p. 9415 - 9418
(2019/05/10)
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- Rate Enhancement in CAN-Promoted Pd(PPh3)2Cl2-Catalyzed Oxidative Cyclization: Synthesis of 2-Ketofuran-4-carboxylate Esters
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Stoichiometric ceric ammonium nitrate (CAN) and a catalytic amount of Pd(PPh3)2Cl2 (5 mol %) can rapidly produce multisubstituted 2-ketofuran-4-carboxylate esters from 2-propargylic 1,3-ketoesters via oxidative O-cyclization reaction. Pd(PPh3)2Cl2 was found to be the crucial catalyst as its inclusion greatly enhanced the rate of the reaction and cleanly afforded the products within minutes. Over 30 substrates were successfully converted to the desired compounds in mostly moderate to good yields.
- Ruengsangtongkul, Sureeporn,Chaisan, Nattawadee,Thongsornkleeb, Charnsak,Tummatorn, Jumreang,Ruchirawat, Somsak
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p. 2514 - 2517
(2019/04/30)
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- Gold-Catalyzed Oxidation of Internal Alkynes into Benzils and its Application for One-Pot Synthesis of Five-, Six-, and Seven-Membered Azaheterocycles
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Internal alkynes have been shown to undergo oxidation to substituted benzils (1,2-diarylethane-1,2-diones) by α-picoline N-oxide in the presence of Ph3PAuNТf2 (5 mol-%). In addition to the unsubstituted benzil, the method allows preparing, under markedly mild conditions (50 °C in chlorobenzene), various non-symmetrical products, including heteroaromatic versions thereof which are much more difficult to obtain otherwise. This gold(I)-catalyzed transformation was integrated into one-pot reaction sequence delivering a range of 5- to 7-membered ring systems (imidazoles, quinoxalines, 1,2,4-triazines, pyrazines, and 1,4-diazepines), thus linking these important heterocyclic motifs to the internal alkyne reagent space.
- Dubovtsev, Alexey Yu.,Dar'in, Dmitry V.,Krasavin, Mikhail,Kukushkin, Vadim Yu.
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p. 1856 - 1864
(2019/02/19)
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- Two-Step One-Pot Synthesis of Unsymmetrical (Hetero)Aryl 1,2-Diketones by Addition-Oxygenation of Potassium Aryltrifluoroborates to (Hetero)Arylacetonitriles
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An efficient one-pot two-step procedure for the synthesis of unsymmetrical (hetero)aryl 1,2-diketones has been developed. The reaction proceeds through a palladium-catalyzed nucleophilic addition of potassium aryltrifluoroborates to aliphatic nitriles followed by a copper-catalyzed aerobic benzylic C–H oxygenation using molecular oxygen as a green oxidant. This represents the first example of the direct synthesis of unsymmetrical diaryl 1,2-diketones from arylacetonitriles. This method utilizes inexpensive, stable, nontoxic, and readily available starting materials, is highly effective in the presence of both electron-rich and electron-poor nitriles and aryltrifluoroborates, and tolerates a wide variety of functional groups. The synthetic utility of this transformation was shown by increasing the scale of the reaction and by carrying out the one-pot protocol for the preparation of quinoxaline and benzimidazole derivatives. A plausible reaction mechanism has also been proposed.
- Kumar, Yogesh,Jaiswal, Yogesh,Kumar, Amit
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p. 494 - 505
(2018/02/09)
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- A method for synthesizing derivatives benzil
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The invention discloses a method for synthesizing a benzil derivative. The method comprises the following steps: adding epoxy chalcone compound shown in the formula I, a Selectfluor oxidizing agent and inorganic base into a mixed solvent of acetonitrile and water, stirring for reaction for 4-8 h at 60-100 DEG C, and treating a reaction liquid obtained after the reaction is finished to prepare the benzil derivative shown in the formula II. The synthesis method has the advantages that the raw materials are cheap and easy to obtain, transition metal catalysis is not needed, the oxygen source is easy to obtain and environment-friendly, the reaction condition is mild, the target substrate can be synthesized efficiently, the universality of the functional group is good, and the operation is simple and convenient.
- -
-
Paragraph 0041-0044
(2020/02/07)
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- An unusual chemoselective oxidation strategy by an unprecedented exploration of an electrophilic center of DMSO: A new facet to classical DMSO oxidation
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A conceptually new dimethyl sulfoxide (DMSO) based oxidation process without the use of any activator has been demonstrated for the oxidation of active methylenes and benzhydrols. The developed protocol utilizes the electrophilic center of DMSO for oxidation, which was unexplored before. Mechanistic investigation has confirmed that the source of oxygen is DMSO.
- Chebolu, Rajesh,Bahuguna, Ashish,Sharma, Reena,Mishra, Vivek Kumar,Ravikumar
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p. 15438 - 15441
(2015/10/20)
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- Mild Mn(OAc)3-Mediated Aerobic Oxidative Decarboxylative Coupling of Arylboronic Acids and Arylpropiolic Acids: Direct Access to Diaryl 1,2-Diketones
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A simple and efficient method for the synthesis of diaryl 1,2-diketones has been developed. The reaction represents the first example of diaryl 1,2-diketones that are synthesized directly from arylboronic acids and arylpropiolic acids by a radical pathway in moderate to good yields. This reaction proceeds under mild reaction conditions and with good tolerance of a variety of functional groups. Preliminary mechanistic studies were conducted.
- Lv, Wen-Xin,Zeng, Yao-Fu,Zhang, Shang-Shi,Li, Qingjiang,Wang, Honggen
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supporting information
p. 2972 - 2975
(2015/06/30)
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- Cobalt(II) catalyzed C(sp)-H bond functionalization of alkynes with phenyl hydrazines: Facile access to diaryl 1,2-diketones
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A cobalt acetylacetonate catalyzed oxidative diketonation of alkynes via C(sp)-H bond functionalization has been described. The reaction involves a free-radical mechanism, wherein the phenyl radical formed from phenyl hydrazine couples with Co(ii) activated alkyne to produce 1,2-diketones. The reaction proceeds at room temperature in DMF with the use of Ag2O/air as the oxidizing system. The utility of the protocol for the synthesis of a series of imidazoles including a potent platelet aggregation inhibitor trifenagrel has been demonstrated.
- Bharate, Jaideep B.,Abbat, Sheenu,Sharma, Rohit,Bharatam, Prasad V.,Vishwakarma, Ram A.,Bharate, Sandip B.
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p. 5235 - 5242
(2015/05/13)
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- Copper-catalyzed base-accelerated direct oxidation of C-H bond to synthesize benzils, isatins, and quinoxalines with molecular oxygen as terminal oxidant
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We describe herein an efficient and general copper (II)-catalyzed base-accelerated oxidation of the C-H bond to synthesize benzils and isatins. With similar oxidation system an efficient one-pot procedure for the synthesis of quinoxaline derivatives was realized. The two protocols feature using molecular oxygen as terminal oxidant, low catalyst loading, wide substrate scope, and high functional-group tolerance.
- Yu, Jing-Wen,Mao, Shuai,Wang, Yong-Qiang
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p. 1575 - 1580
(2015/03/14)
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- Aminocatalytic cross-coupling approach via iminium ions to different C-C bonds
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Given the attractive ability of iminium ions to functionalize molecules directly at ostensibly unreactive positions, the reactivity of iminium ions, in which an α CH2 group is replaced by C=O was explored. Background studies on the ability of such iminium cations to promote reactions via an iminium-catalyzed or iminium-equivalent pathway are apparently unavailable. Previously, tandem cross-coupling reactions were reported, in which an iminium ion undergoes nucleophilic 1,2-addition to give a putative three-component intermediate that abstracts a proton in situ and undergoes self-deamination followed by unprecedented DMSO/ aerobic oxidation to generate a-ketoamides. However, later it was observed that iminium ions can generate valuable α-ketoamides through simple aerobic oxidation. In all reactions, iminium ions were generated in situ by reaction of 2-oxoaldehydes with secondary amines.
- Mupparapu, Nagaraju,Battini, Narsaiah,Battula, Satyanarayana,Khan, Shahnawaz,Vishwakarma, Ram A.,Ahmed, Qazi Naveed
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supporting information
p. 2954 - 2960
(2015/02/05)
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- Selectfluor-Mediated Simultaneous Cleavage of C-O and C-C Bonds in α,β-Epoxy Ketones under Transition-Metal-Free Conditions: A Route to 1,2-Diketones
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Selectfluor-mediated simultaneous cleavage of C-O and C-C bonds in α,β-epoxy ketones has been successfully achieved under transition-metal-free conditions. The reaction gives 1,2-diketone compounds in moderate to good yields involving a ring-opening/benzoyl rearrangement/C-C bond cleavage sequence under oxidative conditions.
- Wang, Heng,Ren, Shaobo,Zhang, Jian,Zhang, Wei,Liu, Yunkui
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p. 6856 - 6863
(2015/10/06)
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- Copper-mediated aerobic oxidative cleavage of α,β-unsaturated ketones to 1,2-diketones
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The copper-mediated aerobic oxidative cleavage of α,β- unsaturated ketones to synthesize 1,2-diketones by using potassium acetate as a catalyst and sodium iodide as a promoter in acetic acid is described. The protocol has the advantages of using inexpensive and non-toxic raw materials, high yield and simple work-up procedure. the Partner Organisations 2014.
- Li, Zheng,Yin, Junjun,Wen, Gong,Li, Tianpeng,Shen, Xiaoli
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p. 32298 - 32302
(2014/08/18)
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- Asymmetric transfer hydrogenation of unsymmetrical benzils
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In this paper, the asymmetric transfer hydrogenation of unsymmetrical benzils with m, p-substituents was conducted with a substrate/catalyst molar ratio of 100 at 40°C for 24 h to produce (S,S)-hydrobenzoins in good yields (76.2% to 97.1%) with high diastereomeric (syn/anti = 10.8 to 29.7/1) and enantiomeric purities (86.1%ee syn to 98.9%ee syn). Unfortunately, the unsymmetrical benzils with the o-substituents such as electron-donating (R = CH3, OCH3) and electron-withdrawing groups (R = F, Cl, CF3) resulted in poor yields (0% to 31.2%), even at 40°C for 72 h. These products had inefficient diastereoselectivities (syn/anti = 1.5 to 5.0/1) caused by steric effects. Furthermore, the results of a dynamic-kinetic study were used to propose a plausible reaction pathway of unsymmetrical benzil using 3-methoxy-1,2-diphenyl ethanedione as an example.
- Zhang, Hao,Feng, Dandan,Sheng, Haibo,Ma, Xuebing,Wan, Jinwei,Tang, Qian
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p. 6417 - 6423
(2014/02/14)
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- Catalyst-controlled highly selective coupling and oxygenation of olefins: A direct approach to alcohols, ketones, and diketones
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Oxygen? That's radical! A method for the direct synthesis of substituted alcohols, ketones, and diketones through a catalyst-controlled highly chemoselective coupling and oxygenation of olefins has been developed. The method is simple and practical, can be switched by the selection of different catalysts, and employs molecular oxygen as both an oxidant and a reagent. Copyright
- Su, Yijin,Sun, Xiang,Wu, Guolin,Jiao, Ning
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supporting information
p. 9808 - 9812
(2013/09/23)
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- Facile and highly chemoselective synthesis of benzil derivatives via oxidation of stilbenes in an I2-H2O system
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A facile and highly chemoselective protocol for the synthesis of benzil derivatives has been developed by oxidation of stilbenes in an I 2-H2O system under air. Notably, the method was applicable to 26 examples and provided up to 98% yield, avoiding the use of acid, metal catalysts and so on.
- Zeng, Xianghua,Miao, Chengxia,Wang, Shoufeng,Xia, Chungu,Sun, Wei
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p. 9666 - 9669
(2013/09/02)
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- Catalytic oxidation of silyl enol ethers to 1,2-diketones employing nitroxyl radicals
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A novel and efficient method for the preparation of 1,2-diketones is reported. A series of -diketones were readily prepared by the nitroxyl-radical-catalyzed oxidation of silyl enol ethers using magnesium monoperoxyphthalate hexahydrate (MMPP6H) as the co-oxidant. Georg Thieme Verlag Stuttgart · New York.
- Hayashi, Masaki,Shibuya, Masatoshi,Iwabuchi, Yoshiharu
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experimental part
p. 1025 - 1030
(2012/06/04)
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- Iron(III)-catalyzed nucleophilic substitution of the hydroxy group in benzoin by alcohols
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The etherification reaction between benzoin derivatives and alcohols catalyzed by iron(III) proceeds in moderate to good yields. Other metal complexes showed either low reactivity or low chemoselectivity where oxidation of benzoin to benzil was a competing reaction. The iron source operated as a catalyst where 5 mol% of iron(III) generate the 2-alkoxy-1,2-diphenylethan-1-one in 50% yield. With an optimum of 25 mol% of catalyst, the desired ether was obtained in 85% yield. The etherification of benzoin and an alcohol proceed to generate the desired product in polar solvents such as 1,2-dichloroethane, whereas less polar solvents promote the competing oxidation to generate the benzil; polar coordinating solvents such as tetrahydrofuran inhibited the reaction. The efficiency of the reaction is found to be dependent on nucleophile where an optimum of 30 equivalents of alcohol was observed. With electron-donating substituents on the aromatic ring, the etherification was followed by oxidation to generate the benzil. Moderate yields of etherification product were obtained by monitoring the reaction progress with electron-rich substrates and quenching the reaction after two hours. Georg Thieme Verlag Stuttgart New York.
- Mirzaei, Anvar,Biswas, Srijit,Samec, Joseph S. M.
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experimental part
p. 1213 - 1218
(2012/06/04)
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- Chemoenzymatic synthesis of chiral unsymmetrical benzoin esters
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A chemoenzymatic Dynamic Kinetic Resolution (DKR) of unsymmetrical benzoins (Ar1≠Ar2) has been carried out, by using Pseudomonas stutzeri lipase stereorecognition pattern. After studying this lipase behaviour, a high preference towards acylation of those benzoins containing substituents in the phenyl ring rather than in the benzoyl moiety was observed. This fact allowed the development of the DKR process of this kind of substrates, avoiding the accumulation of secondary products derived from the in situ racemization mediated by Shvo's catalyst action, and allowing the synthesis of enantiopure unsymmetrical benzoins acetates (not previously described) in very good yields (60-95%) and excellent enantiomeric excess values (always >99%).
- Hoyos, Pilar,Pace, Vittorio,Sinisterra, José V.,Alcántara, Andrés R.
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p. 7321 - 7329
(2011/10/09)
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- Iron-promoted C - C bond cleavage of 1,3-diketones: A route to 1,2-diketones under mild reaction conditions
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A conceptual method for the preparation of 1,2-diketones is reported. The selective C - C bond cleavage of 1,3-diketones affords the 1,2-diketones in high yields under mild reaction conditions in air by the use of FeCl3 as the catalyst and tert-butyl nitrite (TBN) as the oxidant without the use of solvent. The possible reaction mechanism is discussed. This protocol provides an expeditious route to the useful 1,2-diketones.
- Huang, Lehao,Cheng, Kai,Yao, Bangben,Xie, Yongju,Zhang, Yuhong
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experimental part
p. 5732 - 5737
(2011/08/22)
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- Ruthenium-catalyzed oxidation of alkenes at room temperature: A practical and concise approach to α-diketones
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Chemical equations presented. The catalytic oxidation of alkenes to α-diketones is unprecedented. A new oxidation of alkenes, catalyzed by a ruthenium complex, which allows an efficient route to α-diketones using TBHP as an oxidant is described. This methodology is highly functional group tolerant, is practically convenient, requires no additional ligand, and operates under mild conditions with short reaction times. Based upon experimental observations, a plausible mechanism is proposed.
- Chen, Shulin,Liu, Zhaojun,Shi, Erbo,Chen, Long,Wei, Wei,Li, Hong,Cheng, Yannan,Wan, Xiaobing
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supporting information; experimental part
p. 2274 - 2277
(2011/06/27)
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- Synthesis of novel substituted diaryl-1,4-diazepines
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In this paper a convenient route to new 2,3-diaryl-substituted 1,4-diazepines is described through cyclization of ethanedione derivatives and 1,3-propanediamine. The ethanedione derivatives required were synthesized by microwave-assisted oxidation from ethanones.
- Ramajayam,Giridhar, Rajani,Yadav
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p. 901 - 906
(2008/02/12)
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- A convenient preparation of symmetrical and unsymmetrical 1,2-diketones: Application to fluorinated phenytoin synthesis
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1,2-Diketones are efficiently produced in two steps by reaction of aldehydes with anions derived from 2-substituted dithianes followed by treatment of the resulting alcoholis with NBS in aqueous acetone; phenytoin derivatives were prepared from these diketones by a standard method involving treatment with urea and potassium hydroxide under reflux.
- Page,Graham,Park
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p. 7265 - 7274
(2007/10/02)
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- STRUCTURES IN SOLUTION OF ADDUCTS OF 2,8-DIOXA-5-AZA-1-PHOSPHABICYCLOOCTANE AND SUBSTITUTED BENZILS
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Adducts of 2,8-dioxa-5-aza-1-phosphabicyclooctane and p,p'-dimethylbenzil, p-methoxy-p'-fluorobenzil, p-fluorobenzil, p,p'-difluorobenzil, p-nitrobenzil and p,p'-dinitrobenzil have been prepared.Although these materials could not be isolated in pure form because of rapid decomposition, the 31P and other NMR spectral data indicate that all of these materials are pentacoordinate in solution.The NMR data also indicate that all of these adducts undergo rapid intramolecular ligand reorganosation at room temperature.Variable temperature NMR measurements indicate that these rearrangements can be slowed and that they all have virtually the same activation energies, ΔG(excit.) 11.4-11.9 kcal/mole.The barrier to ligand reorganization is associated with the 5-membered dioxa containing ring adopting a diequatorial disposition.These results are discussed and compared to other systems.
- Denney, Donald B.,Denney, Dorothy Z.,Pastor, Stephen D.
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p. 191 - 198
(2007/10/02)
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