- Microwave-assisted solvent-free catalyzed synthesis and luminescence properties of 1,2,4,5-tetrasubstituted imidazoles bearing a 4-aminophenyl substituent
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A solvent-free microwave-assisted four-component synthesis of 1,2,4,5-tetrasubstituted imidazoles bearing a 4-aminophenyl substituent was studied by condensation of p-phenylenediamine, aryl diketone, benzaldehyde derivatives and ammonium acetate in the presence of solid support silica gel and catalyst Keggin-H3[PW12O40]. The effects of four components molar ratio along with catalyst loading, irradiation time on the yields were investigated. Also, the structures of synthesized compounds were characterized by FT-IR, HRMS, 1H NMR and 13C NMR spectroscopy. Furthermore, their ultraviolet-visible maximum absorption, liquid fluorescence emission maximum and quantum yields were, respectively, measured in 0.05 M H2SO4 aqueous solution and in dichloromethane. Simultaneously, solid fluorescence spectra were determined in the powder state. The relationships between the optical behavior and the polarity of the solvents for some compounds were assessed. The results showed that the fluorescence quantum efficiency was increased by introducing amino phenyl in comparison with benzyl on 1-position of trisubstitued imidazoles. The compounds synthesized were sensitive to the polarity of the solvents.
- Yan, Liu-Qing,Chen, Yao,Sun, Xiao-Fu,You, Mao-Jun,Chen, Xiao-Dong,Gu, Qiang,Zhang, Yu-Min
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- Kinetics and mechanism of benzoin oxidation using iron(III) in the presence of ferrozine or 2,2′-bipyridine in acidic medium
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Kinetics and mechanism of oxidation of benzoin (H2B) by ferrozine (Fz) or 2,2′-bipyridine (bipy) have been carried out in aqueous HNO3 medium. The rate shows first-order dependence on [H 2B] and [Fe3+| and inverse second-order dependence on (H+). The rate of reaction increased with increase in the ligand concentration. The increase in dielectric constant will increase the rate, while increase in [HNO3] decreased it. Substituent and temperature effects on the rates have been investigated. The rate laws derived are in excellent agreement with the experimental results. Plausible mechanisms are suggested.
- Al-Sou'od, Khaldoun A.,Ali, Basem F.,Abu-El-Halawa, Rajab,Abu-Nawas, Abd-Al-Hakeem H.
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- OXIDATIVE TRAPPING OF TRANSIENT THIAZOLIUM-ALDEHYDE ADDUCTS BY INTRAMOLECULAR FLAVIN. FLAVIN-THIAMINE BISCOENZYME MODEL
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A biscoenzime which has within a molecular structure both flavin and thiazolium ion was synthesized.In the presence of the biscoenzyme and hexadecyltrimethylammonium bromide (CTAB) micelle, aldehydes were efficiently converted to carboxylic acids and the acyloin condensation products were scarcely detected. Thus, the biscoenzyme serves as an interesting model system for pyruvate dehydrogenase.
- Shinkai, Seiji,Yamashita, Takaharu,Manabe, Osamu
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- Coenzyme Models. 31. Efficient Trapping of Transient Thiazolium-Aldehyde Adducts (Active Aldehydes) by Intramolecular and Quasi-Intramolecular Flavins.Flavin-Thiamin Biscoenzyme
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The reaction sequence of acyloin condensation of aldehydes, catalyzed by thiazolium ion bound to the CTAB micelle, can be diverted by the addition of flavin to the oxidation reaction to afford the corresponding carboxylic acids.It was found, however, that when the aldehyde concentration is elevated or the aldehyde is relatively reactive, intermolecular flavin (3-methyltetra-O-acetylriboflavin, MeFl) cannot trap the intermediates (active aldehydes) formed from thiazolium ion and aldehydes completely, leading to a competition between the conventional acyloin condensation and the flavin oxidation.We have applied the concept of intramolecular catalysis to the system by two methods in order to suppress the acyloin condensation relative to the flavin oxidation.The first utilizes quasi-intramolecular flavin oxidation in which hydrophobic 10-dodecylisoalloxazine (10-DodFl) and N-hexadecylthiazolium bromide (HxdT) are bound to a CTAB micelle aggregate.The second is a flavin-thiazolium biscoenzyme (Fl-T) oxidation in which the intermediates on the thiazolium moiety are oxidized efficiently by the intramolecular flavin.When 4-chlorobenzaldehyde (100mM) was employed as substrate, the trapping efficiency (=flavinoxidation product/sum of acyloin condensation products) for MeFl was 1.6.The trapping efficiency for the quasi-intramolecular flavin oxidation was improved up to 15-33-fold owing to the enhanced local concentration of 10-DodFl in the micelle phase; efficiency for the biscoenzyme system was further enhanced (>115-fold).A kinetic examination has established that the reaction is zero order in MeFl for the intermolecular flavin oxidation of 4-chlorobenzaldehyde, whereas it becomes first order in MeFl for the oxidation of more reactive pyridine-4-carboxaldehyde (pyCHO).This indicates that the rate-limiting step changes depending on the reactivity of aldehyde: the deprotonation from the thiazolium-aldehyde adduct is the limiting in the oxidation of 4-chlorobenzaldehyde, whereas the oxidation of the deprotonated active aldehyde by MeFl becomes rate limiting in the oxidation of pyCHO.On the other hand, quasi-intramolecular flavin oxidation of pyCHO was zero order in 10-DodFl at low pyCHO concentrations (50mM).In the biscoenzyme oxidation of pyCHO, the zero-order decrease was always observed for up to 60percent reaction, indicating the high efficiency of intramolecular flavin as a trapping agent.The present system is a relevant model for pyruvate oxidase which requires FAD and thiamine pyrophosphate as cofactors and catalyzes the convernion of pyruvic acid to acetic acid.
- Shinkai, Seiji,Yamashita, Takaharu,Kusano, Yumiko,Manabe, Osamu
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- FACILE OXIDATION OF ALDEHYDES AND α-KETO ACIDS AS CATALYZED BY FLAVIN AND THIAZOLIUM ION
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Oxidation of aldehydes and α-keto acids to carboxylic acids occurs readily in the presence of a flavin, thiazolium ion, and cationic micelles, the reaction involving trapping by the flavin of the intermediate formed from the substrate-thiazolium adducts through deprotonation or decarboxylation.
- Shinkai, Seiji,Yamashita, Takaharu,Kusano, Yumiko,Manabe, Osamu
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- Synthesis of 1,2-diketones by mercury-catalyzed alkyne oxidation
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The first mercury-catalyzed synthesis of 1,2-diketones by alkyne oxidation has been developed. This inexpensive method extends the potential of mercury catalysis and allows the rapid construction of various 1,2-diketones and α-carbonyl amides in good yields with high functional group tolerance.
- Mei, Xiaochuan,Hu, Weican,Gao, Kexin,Gao, Haotian,Wang, Chaoyang,Qian, Guoying,Rong, Zhouting
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supporting information
p. 2661 - 2667
(2021/07/09)
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- Catalyst-Free and Transition-Metal-Free Approach to 1,2-Diketones via Aerobic Alkyne Oxidation
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A catalyst-free and transition-metal-free method for the synthesis of 1,2-diketones from aerobic alkyne oxidation was reported. The oxidation of various internal alkynes, especially more challenging aryl-alkyl acetylenes, proceeded smoothly with inexpensive, easily handled, and commercially available potassium persulfate and an ambient air balloon, achieving the corresponding 1,2-diketones with up to 85% yields. Meanwhile, mechanistic studies indicated a radical process, and the two oxygen atoms in the 1,2-diketons were most likely from persulfate salts and molecular oxygen, respectively, rather than water.
- Shen, Duyi,Wang, Hongyan,Zheng, Yanan,Zhu, Xinjing,Gong, Peiwei,Wang, Bin,You, Jinmao,Zhao, Yulei,Chao, Mianran
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p. 5354 - 5361
(2021/05/05)
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- One-pot cascade synthesis of α-diketones from aldehydes and ketones in water by using a bifunctional iron nanocomposite catalyst
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A new methodology for the synthesis of α-diketones was reportedviaa one-pot cascade process from aldehydes and ketones catalyzed by a bifunctional iron nanocomposite using H2O2as a green oxidant in water. The one-pot strategy showed excellent catalytic stability, comprehensive suitability of substrates and important practical utility for directly synthesizing biologically active and medicinally valuable N-heterocyclesviaan intermittent process.
- Song, Tao,Zhou, Xin,Wang, Xiaoxue,Xiao, Jianliang,Yang, Yong
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supporting information
p. 1955 - 1959
(2021/03/26)
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- 1-butyl-3-methylimidazol-2-ylidene as an efficient catalyst for cross-coupling between aromatic aldehydes and N-aroylbenzotriazoles
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Cross-coupling of aromatic aldehydes with N-aroylbenzotriazoles in [Bmim]Br in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) provided an efficient procedure for the synthesis of 1,2-diarylethane-1,2-diones.
- Phungpis, Baramee,Hahnvajanawong, Viwat
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p. 651 - 657
(2021/02/27)
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- Conversion of alkynes into 1,2-diketones using HFIP as sacrificial hydrogen donor and DMSO as dihydroxylating agent
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A metal-free and hypervalent iodine free conversion of internal alkynes into 1,2-diketo compounds has been described. The efficacy of the present protocol rely on the use of HFIP (1,1,1,3,3,3-Hexafluoro-2-propanol) as reducing agent of alkynes and DMSO as dihydroxylating agent of olefins to acquire the desired chemical transformations. The obtained 1,2-diketones were further transformed into useful derivatives.
- Gujjarappa, Raghuram,Vodnala, Nagaraju,Putta,Ganga Reddy, Velma,Malakar, Chandi C.
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supporting information
(2020/01/21)
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- Aerobic oxidation of alcohols catalyzed by in situ generated gold nanoparticles inside the channels of periodic mesoporous organosilica with ionic liquid framework
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In situ generated gold nanoparticles inside the nanospaces of periodic mesoporous organosilica with an imidazolium framework (Au?PMO-IL) were found to be highly active, selective, and reusable catalysts for the aerobic oxidation of activated and nonactivated alcohols under mild reaction conditions. The catalyst was characterized by nitrogen adsorption-desorption measurement, thermogravimetric analysis (TGA), transmission electron microscopy (TEM), elemental analysis (EA), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The catalyst exhibited excellent catalytic activity in the presence of either Cs2CO3 (35 °C) or K2CO3 (60 °C) as reaction bases in toluene as a reaction solvent. Under both reaction conditions, various types of alcohols (up to 35 examples) including activated benzylic, primary and secondary aliphatic, heterocyclic, and challenging cyclic aliphatic alcohols converted to the expected carbonyl compounds in good to excellent yields and selectivity. The catalyst was also recovered and reused for at least seven reaction cycles. Data from three independent leaching tests indicated that amounts of leached gold particles were negligible (0.2 ppm). It is believed that the combination of bridged imidazolium groups and confined nanospaces of PMO-IL might be a major reason explaining the remarkable stabilization and homogeneous distribution of in situ generated gold nanoparticles, thus resulting in the highly active and recyclable catalyst system.
- Bigdeli, Akram,Karimi, Babak,Khodadadi Karimvand, Somaiyeh,Khorasani, Mojtaba,Safari, Ali Asghar,Vali, Hojatollah
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supporting information
p. 70 - 79
(2020/06/08)
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- Substituent Effect in the Synthesis of α,α-Dibromoketones, 1,2-Dibromalkenes, and 1,2-Diketones from the Reaction of Alkynes and Dibromoisocyanuric Acid
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Internal alkynes reacted with dibromoisocyanuric acid/H2O to afford α,α-dibromoketone and 1,2-diketone derivatives. Diarylalkynes with activating groups provided 1,2-diketone derivatives as the major products, whereas diarylalkynes with a non-activating group or alkylarylalkynes gave α,α-dibromoketone derivatives as the major products. In addition, diarylalkynes with deactivating groups provided 1,2-dibromoalkenes. The reaction was conducted at room temperature and showed good yields in most cases. Reaction pathways have been proposed on the basis of experimental observations and density functional theory (DFT) calculations. (Figure presented.).
- Cho, Eunjeong,Jayaraman, Aravindan,Lee, Junseong,Ko, Kyoung Chul,Lee, Sunwoo
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p. 1846 - 1858
(2019/03/07)
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- B2pin2-mediated copper-catalyzed oxidation of alkynes into 1,2-diketones using molecular oxygen
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An intriguing aerobic oxidation of alkynes through copper catalysis is described, in which bis(pinacolato)diboron (B2pin2) played a dominant intermediary role in the formation 1,2-diketones. This novel protocol, which can be performed at room temperature, is versatile for various substituted alkynes, including diarylalkynes and arylalkylalkynes. The mechanism of this reaction was preliminarily investigated by control experiments.
- Zhai, Yadong,Su, Zhenni,Jiang, Hao,Rong, Jing,Qiu, Xianfan,Tao, Chuanzhou
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supporting information
p. 843 - 846
(2019/02/19)
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- Ring Closing Metathesis Approach for the Synthesis of o-Terphenyl Derivatives
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A linear synthesis of o-terphenyl derivatives has been delineated using ring closing metathesis (RCM) as the key step. In this approach, benzil derivatives upon allyl Grignard addition provides diphenyl-1,2-diallyl dihydroxy derivatives which undergo ring closing metathesis to afford tetrahydro terphenyl derivatives. Aromatization-driven dehydration then leads to a diverse set of electron rich and electron deficient o-terphenyls. Furthermore, oxidative coupling of electron rich o-terphenyls provides the corresponding triphenylene derivatives.
- Karmakar, Shilpi,Mandal, Tirtha,Dash, Jyotirmayee
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p. 5916 - 5924
(2019/08/21)
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- Computer-aided studies for novel arylhydantoin 1,3,5-triazine derivatives as 5-HT6 serotonin receptor ligands with antidepressive-like, anxiolytic and antiobesity action in vivo
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This study focuses on the design, synthesis, biological evaluation, and computer-aided structure-activity relationship (SAR) analysis for a novel group of aromatic triazine-methylpiperazines,with an hydantoin spacer between 1,3,5-traizine and the aromatic fragment. New compounds were synthesized and their affinities for serotonin 5-HT6, 5-HT1A, 5-HT2A, 5-HT7, and dopamineD2 receptorswere evaluated. The induced-fit docking (IFD) procedure was performed to explore the 5-HT6 receptor conformation space employing two lead structures. It resulted in a consistent binding mode with the activity data. For the most active compounds found in each modification line, anti-obesity and anti-depressive-like activity in vivo, as well as "druglikeness" in vitro, were examined. Two 2-naphthyl compounds (18 and 26) were identified as themost active 5-HT6R agents within each leadmodification line, respectively. The 5-(2-naphthyl)hydantoin derivative 26, themost active one in the series (5-HT6R: Ki = 87 nM), displayed also significant selectivity towards competitive G-protein coupled receptors (6-197-fold). Docking studies indicated that the hydantoin ring is stabilized by hydrogen bonding, but due to its different orientation, the hydrogen bonds formwith S5.44 and N6.55 or Q6.58 for 18 and 26, respectively. Compound 26 exerted anxiolytic-like and antidepressant-like activities. Importantly, it demonstrated anti-obesity properties in animals fed palatable feed, and did not show toxic effects in vitro.
- Kurczab, Rafal,Ali, Wesam,?azewska, Dorota,Kotánska, Magdalena,Jastrzebska-Wiesek, Magdalena,Sata?a, Grzegorz,Wiecek, Ma?gorzata,Lubelska, Annamaria,Latacz, Gniewomir,Partyka, Anna,Starek, Ma?gorzata,Dabrowska, Monika,Weso?owska, Anna,Jacob, Claus,Kiéc-Kononowicz, Katarzyna,Handzlik, Jadwiga
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- Silver-Catalyzed Decarboxylative Couplings of Acids and Anhydrides: An Entry to 1,2-Diketones and Aryl-Substituted Ethanes
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Silver-catalyzed oxidative decarboxylative couplings of carboxylic acids and anhydrides to produce 1,2-diketones and substituted ethanes were developed. This reaction allows the generation of acyl or alkyl radicals by decarboxylation of the corresponding α-keto acids, alkyl acids and anhydrides, which are sequentially coupled to efficiently construct a new C?C bond. This reaction represents a carboxylic acid decarboxylative alternative that employs a radical termination strategy. (Figure presented.).
- Zou, Hua-Xu,Li, Yang,Yang, Yuan,Li, Jin-Heng,Xiang, Jiannan
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supporting information
p. 1439 - 1443
(2018/02/26)
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- Vanadium-Catalyzed Oxidative C(CO)-C(CO) Bond Cleavage for C-N Bond Formation: One-Pot Domino Transformation of 1,2-Diketones and Amidines into Imides and Amides
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A novel vanadium-catalyzed one-pot domino reaction of 1,2-diketones with amidines has been identified that enables their transformation into imides and amides. The reaction proceeds by dual acylation of amidines via oxidative C(CO)-C(CO) bond cleavage of 1,2-diketones to afford N,N′-diaroyl-N-arylbenzamidine intermediates. In the reaction, these intermediates are easily hydrolyzed into imides and amides through vanadium catalysis. This method provides a practical, simple, and mild synthetic approach to access a variety of imides as well as amides in high yields. Moreover, one-step construction of imide and amide bonds with a long-chain alkyl group is an attractive feature of this protocol.
- Digwal, Chander Singh,Yadav, Upasana,Ramya, P. V. Sri,Sana, Sravani,Swain, Baijayantimala,Kamal, Ahmed
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p. 7332 - 7345
(2017/07/26)
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- Synthesis of smart bimetallic nano-Cu/Ag@SiO2 for clean oxidation of alcohols
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Here, we have demonstrated the synthesis and characterization of silica supported bimetallic copper/silver nanoparticles (Cu/Ag@SiO2 NPs) and their application in the clean oxidation of benzoins/benzyl alcohols in the presence of tert-butyl hydroperoxide as a mild oxidant. All the reactions were very fast (4 h) and high yielding (95-99%), and the Cu/Ag@SiO2 NPs were very stable under the reaction conditions. The catalyst was recovered simply by filtration and reused eight times without loss of its catalytic performance.
- Saha, Arijit,Payra, Soumen,Banerjee, Subhash
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p. 13377 - 13381
(2017/11/27)
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- NaBrO3/bmim[HSO4]: a versatile system for the selective oxidation of 1,2-diols, α-hydroxyketones, and alcohols
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Abstract: Sodium bromate with bmim[HSO4] has been found to be an excellent oxidizing agent in aqueous medium. NaBrO3:bmim[HSO4] oxidized 1,2-diols, α-hydroxyketones, and alcohols to the corresponding carbonyl compounds in excellent yields. This method offers advantages such as low cost reagents, aqueous reaction conditions, moderate temperatures and short reaction times and hence environmentally benign reaction. Moreover, the ionic liquid bmim[HSO4] could be recycled for at least three times without loss of significant activity. Graphical abstract: [Figure not available: see fulltext.]
- Khurana, Jitender M.,Lumb, Anshika,Chaudhary, Ankita
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p. 381 - 386
(2017/02/10)
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- CO2-assisted synthesis of non-symmetric α-diketones directly from aldehydes: Via C-C bond formation
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CO2-assisted various symmetric and non-symmetric α-diketones have been synthesized directly from the corresponding aldehydes using transition metal-free catalysts. This method can even be applied to synthesize pharmaceuticals directly from aldehydes. The crucial role of CO2 has been investigated in detail and the mechanism is proposed on the basis of experiments and DFT calculations.
- Hirapara, Pradipbhai,Riemer, Daniel,Hazra, Nabanita,Gajera, Jignesh,Finger, Markus,Das, Shoubhik
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supporting information
p. 5356 - 5360
(2017/11/22)
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- Solvent-Free Condensation Reactions to Synthesize Five-Membered Heterocycles Containing the Sulfamide Fragment
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We report a study of the solvent-free condensation reaction of 1,2-dicarbonyl compounds with sulfamide catalyzed by a Keggin-type acid (H3PMo12O40·nH2O, MPA) to obtain 3,4-disubstituted 1,2,5-thiadiazole 1,1-dioxide derivatives. Some reactions were also performed in solution or using nano-sized silica-supported MPA catalyst in order to compare the results under different experimental conditions. Effects of the temperature used for the thermal pretreatment of the catalyst, the reaction temperature, the molar ratios sulfamide/1,2-dicarbonyl compound and MPA/1,2-dicarbonyl compound, and alternative experimental procedures on the yield of the reaction product were investigated. Under suitable experimental conditions eight compounds were obtained in good yields. The catalyst was recycled and reused, but with some loss of its catalytic activity. The presented synthetic method is a simple, clean, and environmentally friendly alternative for synthesizing different 1,2,5-thiadiazole 1,1-dioxide derivatives.
- Arroyo, Nelson Rodríguez,Rozas, María F.,Vázquez, Patricia,Romanelli, Gustavo P.,Mirífico, María V.
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p. 1344 - 1352
(2016/05/02)
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- Dendrimer-like core cross-linked micelle stabilized ultra-small gold nanoclusters as a robust catalyst for aerobic oxidation of α-hydroxy ketones in water
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As one of the most general and promising stabilizers, dendrimers have been widely used to prepare ultra-small gold nanoclusters. However, the complex synthesis of dendrimers hinders the further application of protected nanoclusters. Here we report a facile strategy to prepare an alternative material via core cross-linking of self-assembled micelles. The resulting dendrimer-like core cross-linked micelles (DCCMs) retain the main characteristics of dendrimers and avoid complex chemical synthesis. As expected, the DCCMs could easily encapsulate gold nanoparticles within their cores. The ultra-small clusters of Au5 were prepared without the participation of external reductants. Importantly, the DCCM stabilized noble gold clusters furnish excellent catalytic activity and perfect reusability for aerobic oxidation of α-hydroxy ketones in water. Only in open air the oxidation could be repeated up to 48 times with negligible turn-over frequency change. The total turnover number (TON) of the reaction reached unexpectedly >48 000, the highest TON for metal catalysed oxidation of hydroxy ketones so far. The further mechanism study hints that the carboxylic group of substrates might be involved in the catalytic process. The simple catalyst preparation, the environmentally benign reaction conditions, and the excellent catalytic performance and durability make the novel DCCM protected gold nanocluster a green catalyst.
- Yu, Yangyang,Lin, Chenlu,Li, Bing,Zhao, Pengxiang,Zhang, Shiyong
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p. 3647 - 3655
(2016/07/06)
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- Lanthanum triflate-catalyzed rapid oxidation of secondary alcohols using hydrogen peroxide urea adduct (UHP) in ionic liquid
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A convenient and efficient protocol for the oxidation of secondary hydroxyl group to ketone using hydrogen peroxide-urea adduct and catalytic (CF 3SO3)3La in ionic liquid has been developed. A number of 1,2-diols, -hydroxyketones, and other aromatic and aliphatic secondary alcohols have been successfully oxidized to the corresponding ketones using this protocol in good yields and short reaction times. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Saluja, Pooja,Magoo, Devanshi,Khurana, Jitender M.
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supporting information
p. 800 - 806
(2014/03/21)
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- Design, synthesis and biological evaluation of 2, 4, 5-triphenylimidazole derivatives with preliminary SAR
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A series of N1-substituted 2,4,5-triphenyl imidazole derivatives was designed, synthesized and evaluated for their p53-MDM2 binding inhibitory activities and anti-proliferative activities in vitro against four human cancer cell lines (PC3, KB, A549 and HCT116). Although logical evaluation revealed weak p53-MDM2 binding inhibitory activities, most of the obtained molecules displayed moderate to potent cytotoxicities against tested cell lines. As a potential lead compound for further optimization, compound 9c was evaluated as the most potent compound against four cell lines and could induce cell cycle arrest at G2/M phase. The binding mode of compound 9f and MDM2 was further studied by docking analysis and the unexpected interaction mode revealed that this series of compounds may take part into a different binding modes as the lead compound Such as Nutlin, which could induce a different mechanism in cancer therapy.
- Hu, Chunqi,Shen, Jianfeng,Bian, Kejun,Zhang, Ruoyu,Deng, Liping
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p. 762 - 769
(2014/07/07)
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- Synthesis and anticancer activity of 2,4,5-triaryl imidazole derivatives
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This study describes the synthesis of four 2,4,5-triarylimidazole derivatives and their anticancer activities. The target compounds were prepared from the reaction of benzaldehyde and benzoin derivatives in presence of ammonium acetate and ammonium vanadate. All the synthesized compounds were screened for anticancer activities against T47D and MDA-MB231 cell lines using the MTT assay. However, our obtained results indicated a significant difference between colchicines cytotoxicity and their homologs on treated MDA-MB231 and T47D cells; one compound (4a) showed a significant IC50 on MDA-MB231 cells in cell culture assay.
- Elahian, Fatemeh,Akbari, Morteza,Ghasemi, Maryam,Behtooee, Neda,Taheri, Mohaddeseh,Amini, Mohsen
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p. 840 - 843
(2014/07/21)
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- N-Heterocyclic carbene-catalyzed double acylation of enones with benzils
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Thiazolium carbene-catalyzed reaction of aromatic 1,2-diketones with enones in aprotic solvents gave double acylation products in good yields, whereas hydroacylation products formed by Stetter reaction were not detected at all. These results suggested the generation of aroyloxyenamine species from the 1,2-diketones instead of hydroxyenamines (Breslow intermediates). This journal is
- Takaki, Ken,Ohno, Akira,Hino, Makoto,Shitaoka, Takashi,Komeyama, Kimihiro,Yoshida, Hiroto
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supporting information
p. 12285 - 12288
(2014/12/11)
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- SBA-15-Functionalized 3-Oxo-ABNO as Recyclable Catalyst for Aerobic Oxidation of Alcohols under Metal-Free Conditions
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The nitroxyl radical 3-oxo-9-azabicyclo [3.3.1]nonane-N-oxyl (3-oxo-ABNO) has been prepared using a simple protocol. This organocatalyst is found to be an efficient catalyst for the aerobic oxidation of a wide variety of alcohols under metal-free conditions. In addition, the preparation and characterization of a supported version of 3-oxo-ABNO on ordered mesoporous silica SBA-15 (SABNO) is described for the first time. The catalyst has been characterized using several techniques including simultaneous thermal analysis (STA), transmission electron microscopy (TEM), and nitrogen sorption analysis. This catalyst exhibits catalytic performance comparable to its homogeneous analogue and much superior catalytic activity in comparison with (2,2,6,6-tetramethylpiperidin-1-yl)oxy (TEMPO) for the aerobic oxidation of almost the same range of alcohols under identical reaction conditions. It is also found that SABNO can be conveniently recovered and reused at least 12 times without significant effect on its catalytic efficiency.
- Karimi, Babak,Farhangi, Elham,Vali, Hojatollah,Vahdati, Saleh
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p. 2735 - 2741
(2016/12/23)
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- Unexpected transformation of aldehydes into benzoins with Copper(I)/Samarium
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The reductive coupling of aldehydes to afford pinacolic alcohols using all kinds of reducing agents involving samarium is well known. In this report, however, treatment of aromatic aldehydes with Cu(I)/Sm system produces benoins and/or benzils in good yields. A possible mechanism is proposed where Cu(I) not only activates the Sm metal but also promotes the dehydrogenation of the intermediates, during which a Cu(III) species may be involved. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications for the following free supplemental resource(s): Full experimental and spectral details.]
- Liu, Yongjun,Wang, Hui,Fu, Yulong,Qi, Yan,Yang, Kuiwei
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p. 259 - 266
(2013/12/04)
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- Synthesis of ferrocene derivatives with planar chirality via palladium-catalyzed enantioselective C-H bond activation
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The first catalytic and enantioselective C-H direct acylation of ferrocene derivatives has been developed. A series of 2-acyl-1-dimethylaminomethylferrocenes with planar chirality were provided under highly efficient and concise one-pot conditions with up to 85% yield and 98% ee. The products obtained could be easily converted to various chiral ligands via diverse transformations.
- Pi, Chao,Cui, Xiuling,Liu, Xiuyan,Guo, Mengxing,Zhang, Hanyu,Wu, Yangjie
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p. 5164 - 5167
(2014/12/11)
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- Mechanism of the electrocatalytic reduction of protons with diaryldithiolene cobalt complexes
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A series of dimeric cobalt-diaryldithiolene complexes [Co(S 2C2Ar2)2]2, possessing various aryl para substituents (OMe, F, Cl, and Br), were studied as electrocatalysts for proton reduction in nonaqueous media, in an effort to correlate dithiolene donor strength with catalyst activity. Cyclic voltammetry data acquired for the cobalt-diaryldithiolene dimers guided the isolation of chemically reduced monoanionic ([Co(S2C2Ar 2)2]-) and dianionic ([Co(S2C 2Ar2)2]2-) monomers. The potassium and tetrabutylammonium salts of dianionic cobalt-diaryldithiolene complexes have been characterized by single crystal X-ray crystallography. Treatment of the dianionic species with stoichiometric quantities of a weak acid afforded H 2 and the monoanionic cobalt-diaryldithiolene species. Density functional theory (BP86) suggests that hydrogen elimination proceeds through a diprotonated intermediate with a Co-H bond and a protonated S center. A transition state for transfer of the S-H proton to the metal center was located with a computed free energy of 5.9 kcal/mol, in solution (DMF via C-PCM approach).
- Letko, Christopher S.,Panetier, Julien A.,Head-Gordon, Martin,Tilley, T. Don
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p. 9364 - 9376
(2014/07/21)
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- Copper-catalyzed direct synthesis of diaryl 1,2-diketones from Aryl iodides and propiolic acids
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Benzil derivatives such as diaryl 1,2-diketones are synthesized via the direct decarboxylative coupling reaction of aryl propiolic acids and their oxidation. The optimized conditions are that the reaction of aryl propiolic acids and aryl iodides is conducted at 140°C for 6 h in the presence of 10 mol % CuI/Cu(OTf)2 and Cs2CO3, after which HI (aq) is added and further reacted. The method shows good functional group tolerance toward ester, aldehyde, cyano, and nitro groups. In addition, symmetrical diaryl 1,2-diketones are obtained from aryl iodides and propiolic acid in the presence of palladium and copper catalysts.
- Min, Hongkeun,Palani, Thiruvengadam,Park, Kyungho,Hwang, Jinil,Lee, Sunwoo
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p. 6279 - 6285
(2014/07/21)
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- Copper-catalyzed aerobic oxidative C-C bond cleavage of 1,3-diaryldiketones to synthesize 1,2-diketones
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An aerobic oxidative C-C bond cleavage of 1,3-diaryldiketones for the synthesis of 1,2-diketones by using O2 as the oxidant has been developed. Control experiments illustrate that the copper catalyst not only assist the aerobic oxidative process of 1,3-diketones, but also catalyze the 1,2-Wagner-Meerwein-type rearrangement process. Georg Thieme Verlag Stuttgart. New York.
- Zhang, Chun,Wang, Xiaoyang,Jiao, Ning
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supporting information
p. 1458 - 1460
(2014/06/23)
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- A combination of copper(0) powder and selectfluor enables generation of cationic copper species for mild 1,2-dicarbonylation of alkynes
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A combination of copper powder and Selectfluor permits the generation of cationic copper species that efficiently catalyze 1,2-dicarbonylation of alkynes under mild conditions with water and dioxygen as inexpensive and environmentally benign sources of oxygen. Georg Thieme Verlag Stuttgart New York.
- Zhang, Wenxia,Zhang, Jian,Liu, Yunkui,Xu, Zhenyuan
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supporting information
p. 2709 - 2714
(2014/01/06)
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- YbCl3-catalyzed one-pot synthesis of dihydropyrazines, piperazines, and pyrazines
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A simple and efficient synthetic approach to dihydropyrazines via YbCl 3-catalyzed reaction of α-hydroxyketones with diamines under mild conditions was developed. The corresponding 2,3-subsitituted piperazines and pyrazines were obtained through tandem conversion of dihydropyrazines with good yields.
- Fan, Liyan,Chen, Wen,Qian, Changtao
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supporting information
p. 231 - 234
(2013/02/23)
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- CuI-catalyzed and air promoted oxidative cyclization for one-pot synthesis of polyarylated oxazoles
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A facile CuI-catalyzed and air promoted oxidative cyclization was developed for the synthesis of polyarylated oxazoles. By virtue of this method, a variety of arylated oxazoles could be easily synthesized from readily available starting materials at room temperature in air. The Royal Society of Chemistry 2013.
- Hu, Ping,Wang, Qiang,Yan, Yizhe,Zhang, Shuai,Zhang, Baiqun,Wang, Zhiyong
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supporting information
p. 4304 - 4307
(2013/08/23)
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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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p. 1025 - 1030
(2012/06/04)
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- Direct carbo-acylation reactions of 2-arylpyridines with α-diketones via Pd-catalyzed C-H activation and selective C(sp2)-C(sp2) cleavage
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An efficient carbo-acylation reaction of 2-arylpyridines with α-diketones via Pd-catalyzed C-H bond activation and C-C bond cleavage in the presence of TBHP was developed that generated aryl ketones in good yields. The highly selective formation of aryl ketones was observed when 2-arylpyridines reacted with aromatic/aliphatic α-diketones.
- Zhou, Wei,Li, Hongji,Wang, Lei
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supporting information
p. 4594 - 4597
(2012/10/29)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Celine,Alexakis, Alexandre
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supporting information
p. 4906 - 4909,4
(2012/12/12)
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- N-heterocyclic carbene-catalyzed annulation of α-cyano-1,4-diketones with ynals
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In this paper, the first stereoselective annulation reaction between r-cyano-1,4-diketones and ynals, mediated by catalytic amounts of a triazolium salt precatalyst and cocatalytic amounts of a weak carboxylate base, is disclosed. The title transformation proceeds smoothly under mild reaction conditions and generates three contiguous stereogenic centers, one of which is a quaternary acetal carbon. This reaction tolerates a wide variety of electronically distinct substituents on both reaction partners and affords privileged bicyclic scaffolds in 61-90% isolated yields and with up to 20:1 diastereomeric preference.
- Romanov-Michailidis, Fedor,Besnard, Céline,Alexakis, Alexandre
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supporting information
p. 4906 - 4909
(2013/01/15)
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- Metal-free oxidation of α-hydroxy ketones to 1,2-diketones catalyzed by mesoporous carbon nitride with visible light
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As a photocatalyst, mesoporous carbon nitride (mpg-C3N 4) shows higher photocatalytic activities in organic synthesis. Herein we report an mpg-C3N4-catalyzed oxidation of α-hydroxy ketones to synthesize 1,2-diketones using visible light. This transformation represents a green and highly efficient synthetic route to synthesize 1,2-diketones for which catalytic approaches are scarce.
- Zheng, Zhishuo,Zhou, Xiaosong
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p. 1683 - 1686,4
(2020/08/31)
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- N-heterocyclic carbene catalyzed one-pot synthesis of 2,3- diarylquinoxalines
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A one-pot efficient and facile protocol for the direct synthesis of quinoxaline derivatives via tandem N-heterocyclic carbene (NHC)-catalyzed umpolung of aldehydes/oxidation of the benzoins to benzils/condensation of benzils with benzene-1,2-diamines has been developed. Georg Thieme Verlag Stuttgart New York.
- Lin, Yang,Lei, Xiaoli,Yang, Qin,Yuan, Jiangjun,Ding, Qiuping,Xu, Jingshi,Peng, Yiyuan
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supporting information
p. 2699 - 2706
(2012/11/13)
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- Iodine-catalyzed synthesis of 1,2-diaryldiketones by oxidative cleavage of 1,3-diaryldiketones with DMSO
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A metal-free, efficient, practical, and convenient process based on an iodine-catalyzed oxidative cleavage reaction has been developed to form 1,2-diaryldiketons in high yields from 1,3-diaryldiketones. The reaction is performed in DMSO and in air, and a mechanism was proposed according to the reaction evidence. Copyright
- Yuan, Yu,Zhu, Haitao
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experimental part
p. 329 - 333
(2012/02/04)
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- Nanosized Mn(acac)3 anchored on amino functionalized silica for the selective oxidative synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles and aerobic oxidation of benzoins in water
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Silica functionalized Mn(acac)3 was prepared and employed for the one-pot oxidative synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles; and oxidation of benzoins to benzils under air atmosphere using water as the reaction medium. Environmentally friendly procedure, chemoselectivity and excellent yields are main advantages of this procedure. In all the cases, the catalyst was found to be highly active and selective; passes hot filtration test successfully; and could be recycled several times with a slight loss of activity. Graphical Abstract: SiO2-Mn(acac)3 catalyzed synthesis of 2-arylbenzimidazoles, 2-arylbenzothiazoles and oxidation of benzoins in air [Figure not available: see fulltext.]
- Sodhi, Ravinderpal Kour,Paul, Satya
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experimental part
p. 608 - 615
(2012/01/13)
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- Oxidation of benzoins to benzils with chromium trioxide under viscous conditions
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An efficient and selective oxidation of benzoins into corresponding benzils using chromium trioxide under viscous conditions at room temperature is described. The present oxidations are completed within 2 h with the yield of 86-96%. It can overcome the problems of the common solvent-free reactions, in which it is difficult for the solid molecular collision to react.
- Huang, Li-Hong,Wang, Qiang,Ma, Yi-Chun,Lou, Ji-Dong,Zhang, Changhe
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experimental part
p. 1659 - 1663
(2011/06/21)
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- Zinc-catalyzed aerobic oxidation of benzoins and its extension to enantioselective oxidation
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Zn(II)-DABCO complex is used as an efficient catalyst for the aerobic oxidation of benzoins to benzils in the presence of molecular oxygen. Usage of chiral zinc complex as catalyst resulted in enantioselective oxidative kinetic resolution of racemic benzoin to yield enantiomerically enriched benzoins.
- Muthupandi, Pandi,Sekar, Govindasamy
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supporting information; experimental part
p. 692 - 695
(2011/03/21)
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- A highly recyclable magnetic core-shell nanoparticle-supported TEMPO catalyst for efficient metal- and halogen-free aerobic oxidation of alcohols in water
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The selective oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is one of the most challenging reactions in organic chemistry. Many oxidizing reagents such as stoichiometric CrVI salts, DMSOcoupled reagents, and hypervalent iodine have been traditionally used to accomplish this transformation. However, these reagents show poor atom efficiency and are often toxic; their widespread use thereby causes significant environmental concerns that render them impractical. As a consequence, due to ever-increasing environmental standards and economic pressures, there is substantial interest towards the use of heterogeneous and recyclable catalysts to achieve the efficient oxidation of alcohols with molecular oxygen or air as the oxidant. Whereas methodologies for the improvement of catalytic activities and selectivities have been developed considerably, they may possibly leave toxic traces of heavy metals in the products. Moreover, many of the metal-based catalyst systems are often deactivated because of the occupation of coordination sites with the by-produced water and so they generally require the use of organic solvents. Therefore, it seems that there is still a great interest in developing efficient and non-metallic catalysts for the aerobic oxidation of alcohols from the viewpoint of socalled green and sustainable chemistry. Of particular interest in this area is the application of the stable nitroxyl radical 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) in combination with various types of non-metallic, stoichiometric co-oxidants as an alternative to metal-based oxidants.
- Karimi, Babak,Farhangi, Elham
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supporting information; experimental part
p. 6056 - 6060
(2011/06/26)
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- One-pot synthesis benzils from aldehydes via nhc-catalyzed benzoin dimerization under metal-free conditions in water
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A simple and convenient one-pot procedure is reported for the synthesis of 1,2-diketones from corresponding benzoin-type condensation reaction of aromatic aldehydes in water with N,N-dialkylbenzimidazolium salt as condensation catalyst and air as oxidizing reagent.
- Bi, Xiaoxin,Wu, Lintao,Yan, Chaoguo,Jing, Xiaobi,Zhu, Hongxiang
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scheme or table
p. 663 - 664
(2012/02/02)
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- Enantioselective aerobic oxidation of α-hydroxy-ketones catalyzed by oxidovanadium(V) methoxides bearing chiral, N-salicylidene- tert -butylglycinates
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Chiral oxidovanadium(V) methoxides prepared from 3,5-disubstituted-N- salicylidene-l-tert-butylglycines and vanadyl sulfate in air-saturated MeOH serve as highly enantioselective catalysts for asymmetric aerobic oxidations and kinetic resolution of alkyl, aryl, and heteroaryl α-hydroxy-ketones with differed α-substituents at ambient temperature in toluene or TBME (tert-butyl methyl ether). The best scenarios involve the use of complexes which bear the tridendate templates derived from 3,5-diphenyl- or 3-o-biphenyl-5-nitro-salicyaldehyde. The kinetic resolution selectivities of the aerobic oxidation process are in the range of 12 to >1000 based on the selectivity factors (krel).
- Chen, Chien-Tien,Kao, Jun-Qi,Salunke, Santosh B.,Lin, Ya-Hui
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supporting information; experimental part
p. 26 - 29
(2011/03/22)
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- Integrated electrochemical-chemical oxidation mediated by alkoxysulfonium Ions
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Generation of carbocations by the "cation pool" method followed by reaction with dimethyl sulfoxide (DMSO) gave the corresponding alkoxysulfonium ions. Alkoxysulfonium ions could also be generated by in situ DMSO trapping of electrochemically generated carbocations. The resulting alkoxysulfonium ions were transformed into carbonyl compounds by treatment with triethylamine. The present integrated electrochemical-chemical oxidation can be applied to the oxidation of diarylmethanes to diaryl ketones, toluenes to benzaldehydes, and aryl-substituted alkenes to 1,2-diketones. Moreover, the oxidation of unsaturated compounds bearing a nucleophilic group in an appropriate position gives cyclized carbonyl compounds.
- Ashikari, Yosuke,Nokami, Toshiki,Yoshida, Jun-Ichi
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supporting information; experimental part
p. 11840 - 11843
(2011/09/21)
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- Utility of dysprosium as a reductant in coupling reactions of acyl chlorides: The synthesis of amides and diaryl-substituted acetylenes
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Reduction of acyl chlorides with dysprosium metal has been studied. The reducing ability of dysprosium metal is solvent-dependent. Dysprosium metal, which requires neither any additive nor pretreatment, can promote the cross-coupling of acyl chlorides in DMF or DEF to give amides in good yields. When the reaction was performed in N,N-dimethylacetamide, the reductive self-coupling reaction of aroyl chloride took place smoothly and afforded the diaryl-substituted acetylenes in moderate to good yield.
- Chen, Weifeng,Li, Kebin,Hu, Ziqiang,Wang, Liliang,Lai, Guoqiao,Li, Zhifang
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experimental part
p. 2026 - 2030
(2011/06/18)
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- An efficient palladium-catalyzed synthesis of benzils from aryl bromides: Vinylene carbonate as a synthetic equivalent of glyoxal
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An expedient synthetic procedure of benzil derivatives from aryl bromides was developed using vinylene carbonate as a glyoxal equivalent in a palladium-catalyzed reaction. The reaction involved a sequential diarylation of vinylene carbonate to form 4,5-diaryl-1,3-dioxol-2-one, ring-opening to benzoin derivative, and an oxidation process.
- Kim, Ko Hoon,Park, Bo Ram,Lim, Jin Woo,Kim, Jae Nyoung
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experimental part
p. 3463 - 3466
(2011/06/27)
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- Novel cobalt(II) complexes of amino acids-Schiff bases catalyzed aerobic oxidation of various alcohols to ketones and aldehyde
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Two cobalt(II) complexes 1 and 2 of Schiff bases derived from amino acids were synthesized and used for oxidation of benzyl alcohol with molecular oxygen at different conditions of pH, solvent, temperature and complex/alcohol molar ratio to optimize reaction conditions and to evaluate the catalytic efficiency of new cobalt Schiff base complexes. Under obtained optimum conditions, various alcohols were oxidized to corresponding aldehydes and ketones.
- Seyedi, Seyed Mohammad,Sandaroos, Reza,Zohuri, Gholam Hossein
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scheme or table
p. 1303 - 1306
(2011/10/05)
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- Facile route to benzils from aldehydes via NHC-catalyzed benzoin condensation under metal-free conditions
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A simple and efficient one-pot procedure for the synthesis of α-diketones from aldehydes via benzoin condensation under the influence of a catalytic amount of azolium salt combined with DBU has been developed. Thus, aldehyde was allowed to react with the azolium salt/DBU catalytic system at room temperature, and then the reaction mixture was heated to 70 °C under air atmosphere to afford the corresponding 1,2-diketone in good yield. This would be an efficient alternative method of synthesizing α-diketones from aldehydes under metal-free conditions. Crown Copyright
- Shimakawa, Yuuki,Morikawa, Takashi,Sakaguchi, Satoshi
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supporting information; experimental part
p. 1786 - 1789
(2010/05/19)
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