- Molecular iodine mediated oxidative cleavage of the C-N bond of aryl and heteroaryl (dimethylamino)methyl groups into aldehydes
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The oxidative cleavage of the C-N bond of aryl and heteroaryl (dimethylamino)methyl groups is achieved by employing molecular iodine as a mild oxidizing agent under ambient conditions in the presence of a mild base. The important reaction of C3 formylation of free NH and substituted indoles containing various substituents is accomplished from the corresponding Mannich bases. This methodology can also be extended for the synthesis of aryl and other heteroaryl aldehydes and ketones. Furthermore, the usefulness of the method is successfully demonstrated on a gram scale.
- Mandrekar, Ketan S.,Tilve, Santosh G.
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supporting information
p. 4152 - 4155
(2021/03/15)
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- Dioxido-vanadium(V) complex catalyzed oxidation of alcohols and tandem synthesis of oximes: a simple catalytic protocol for C–N bond formation
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We report the synthesis of a vanadium(V) complex characterized by FT-IR and 1H NMR spectroscopy. The structure of the complex was established by single crystal X-ray crystallography. We also carried out the catalytic oxidation of benzyl alcohol, hetero-aryl alcohols and propargylic alcohols. Tandem synthesis of oximes from alcohols were also carried out using our vanadium(V) complex. The newly synthesized complex acts as a catalyst for oxidation reactions and tandem synthesis of oxime from alcohols.
- Kurbah, Sunshine Dominic
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p. 905 - 918
(2021/02/03)
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- Efficient aerial oxidation of different types of alcohols using ZnO nanoparticle–MnCO3-graphene oxide composites
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Graphene–metal nanocomposites have been found to remarkably enhance the catalytic performance of metal nanoparticle-based catalysts. In continuation of our previous report, in which highly reduced graphene oxide (HRG)-based nanocomposites were synthesized and evaluated, we present nanocomposites of graphene oxide (GRO) and ZnO nanoparticle-doped MnCO3 ([ZnO–MnCO3/(1%)GRO]) synthesized via a facile, straightforward co-precipitation technique. Interestingly, it was noticed that the incorporation of GRO in the catalytic system could noticeably improve the catalytic efficiency compared to a catalyst (ZnO–MnCO3) without GRO, for aerial oxidation of benzyl alcohol (BzOH) employing O2 as a nature-friendly oxidant under base-free conditions. The impacts of various reaction factors were thoroughly explored to optimize reaction conditions using oxidation of BzOH to benzaldehyde (BzH) as a model substrate. The catalysts were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, Energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and Raman spectroscopy. The (1%)ZnO–MnCO3/(1%)GRO exhibited significant specific activity (67 mmol.g?1.hr?1) with full convversion of BzOH and >99% BzH selectivity within just 6 min. The catalytic efficiency of the (1%)ZnO–MnCO3/(1%)GRO nanocomposite was significantly better than the (1%)ZnO–MnCO3/(1%)HRG and (1%)ZnO–MnCO3 catalysts, presumably due to the existence of oxygen-possessing groups on the GRO surface and as well as a very high surface area that could have been instrumental in uniformly dispersing the active sites of the catalyst, i.e., ZnO–MnCO3. Under optimum circumstances, various kinds of alcohols were selectively transformed to respective carbonyls with full convertibility over the (1%)ZnO–MnCO3/(1%)GRO catalyst. Furthermore, the highly effective (1%)ZnO–MnCO3/(1%)GRO catalyst could be successfully reused and recycled over five consecutive runs with a marginal reduction in its performance and selectivity.
- Adil, Syed Farooq,Assal, Mohamed E.,Shaik, Mohammed Rafi,Kuniyil, Mufsir,Hashmi, Azhar,Khan, Mujeeb,Khan, Aslam,Tahir, Muhammad Nawaz,Al-Warthan, Abdulrahman,Siddiqui, Mohammed Rafiq H.
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- Production of (S)-β-Nitro Alcohols by Enantioselective C?C Bond Cleavage with an R-Selective Hydroxynitrile Lyase
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Hydroxynitrile lyase (HNL)-catalysed stereoselective synthesis of β-nitro alcohols from aldehydes and nitroalkanes is considered an efficient biocatalytic approach. However, only one S-selective HNL—Hevea brasiliensis (HbHNL)—exists that is appropriate for the synthesis of (S)-β-nitro alcohols from the corresponding aldehydes. Further, synthesis catalysed by HbHNL is limited by low specific activity and moderate yields. We have prepared a number of (S)-β-nitro alcohols, by kinetic resolution with the aid of an R-selective HNL from Arabidopsis thaliana (AtHNL). Optimization of the reaction conditions for AtHNL-catalysed stereoselective C?C bond cleavage of racemic 2-nitro-1-phenylethanol (NPE) produced (S)-NPE (together with benzaldehyde and nitromethane, largely from the R enantiomer) in up to 99 % ee and with 47 % conversion. This is the fastest HNL-catalysed route known so far for the synthesis of a series of (S)-β-nitro alcohols. This approach widens the application of AtHNL for the synthesis not only of (R)- but also of (S)-β-nitro alcohols from the appropriate substrates. Without the need for the discovery of a new enzyme, but rather by use of a retro-Henry approach, it was used to generate a number of (S)-β-nitro alcohols by taking advantage of the substrate selectivity of AtHNL.
- Rao, D. H. Sreenivasa,Padhi, Santosh Kumar
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p. 371 - 378
(2019/01/08)
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- Practical Synthesis of Polymethylated Flavones: Nobiletin and Its Desmethyl Derivatives
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We present a practical synthesis of the polymethoxylated citrus flavone nobiletin that is suitable for use on a hundred gram scale. Ready availability of this compound and its derivatives will aid detailed chemical-biological investigations of their biological activities, including activation of signaling via the cAMP-dependent protein kinase A/extracellular signal-related protein kinase/cAMP response element-binding protein pathway.
- Asakawa, Tomohiro,Sagara, Hiroto,Kanakogi, Masaki,Hiza, Aiki,Tsukaguchi, Yuta,Ogawa, Takahiro,Nakayama, Miho,Ouchi, Hitoshi,Inai, Makoto,Kan, Toshiyuki
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p. 595 - 602
(2019/04/01)
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- Electrophilic Aromatic Formylation with Difluoro(phenylsulfanyl) methane
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Difluoro(phenylsulfanyl)methane (PhSCF 2 H) was found to undergo a reaction with aromatic compounds mediated by SnCl 4, through a thionium intermediate characterized by NMR and TD-DFT analyses, leading to the formation of a mixture of S, S ′-diphenyl dithioacetal and aromatic aldehyde which, after oxidative hydrolysis, provides the aromatic aldehyde in good to excellent yields. The salient feature of the present work is the reaction of activated aromatic compounds containing a deactivating ester functional group, leading to the formylated products in good yields.
- Betterley, Nolan M.,Kongsriprapan, Sopanat,Chaturonrutsamee, Suppisak,Deelertpaiboon, Pramchai,Surawatanawong, Panida,Pohmakotr, Manat,Soorukram, Darunee,Reutrakul, Vichai,Kuhakarn, Chutima
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p. 2033 - 2040
(2018/03/21)
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- Peroxidative catalytic oxidation of alcohols catalyzed by heterobinuclear vanadium(V) complexes using H2O2 as terminal oxidizing agents
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Here we report the catalytic oxidation of benzylic alcohol, hetero-aryl alcohols and propargylic alcohols to their corresponding carbonyl compound using heterobimetallic sodium-dioxidovanadium(V) complexes. The present catalytic oxidation studies proceed at 70?°C using H2O2 as terminal oxidant. During the whole process, the complexes react with hydrogen peroxide to form peroxo-vanadium(V) species. The present study shows the heterogeneity of pre-catalyst which could be easily recovered and moreover isolation of product is very simple.
- Kurbah, Sunshine D.,Asthana,Syiemlieh, Ibanphylla,Lal, Ram A.
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- Trimetazidine hydrochloride intermediate preparation method
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The invention discloses a trimetazidine hydrochloride intermediate preparation method. The method takes 1,2,3-trichlorobenzene (II) as a starting raw material; a nucleophilic substitution reaction is performed under catalysis of a catalyst in a methanol solution of sodium methylate for obtaining an intermediate (III); and then a Duff reaction is performed on the intermediate (III), and finally an intermediate (I) is obtained. The solvent used in the method provided by the invention has low toxicity, and can be recycled and reused, so that the three-waste (waste gas, waste water and industrial residue) emission is reduced. The method simplifies the operation steps, reduces the production cost and is more beneficial to industrial reactions. The post-treatment process of the method is simpler, so that on the basis of increasing impurity removing efficiency, the complexity of the technological process is reduced further.
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Paragraph 0021; 0022; 0024; 0026; 0028
(2017/12/27)
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- Synthesis, characterization, and catalytic activity of a water soluble copper(II) and nickel(II) heterobimetallic complex [CuNi(μ-OH)(μ-OH2)(μ-OAc)(bpy)2](ClO4)2 in aqueous medium in the absence of a base and co-catalyst
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A copper(II)–nickel(II)-based catalyst system has been synthesized and characterized by elemental analysis, molar conductance, mass spectra, magnetic moment, EPR, UV-Vis, IR spectroscopy, and cyclic voltammetry. The structure of the complex was established by X-ray crystallography. The complex is an efficient catalyst, which oxidizes primary and secondary alcohols to the corresponding aldehydes and ketones at 70?°C employing 15% H2O2 as the oxidant in the absence of a base and co-catalyst.
- Lal, Ram A.,Kumar, Arvind,Syiemlieh, Ibanphylla,Kurbah, Sunshine D.
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p. 2722 - 2735
(2017/09/06)
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- Bimetallic cis-dioxomolybdenum(VI) complex containing hydrazone ligand: Syntheses, crystal structure and catalytic studies
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Bimetallic molybdenum(VI) complex [(MoO2)2(slsch)(H2O)2] containing dihydrazone ligand was synthesized by reaction of ligand with MoO2(acac)2 in 1:2 M ratio in methanol. The bimetallic complex obtained was characterized by various spectroscopic studies. The structure of complex was assigned using Single Crystal X-ray Crystallography and DFT method. We have also explored the catalytic behavior of complex for oxidation of primary benzylic, aliphatic, allylic, and propargylic alcohols.
- Kurbah, Sunshine Dominic,Kumar, Arvind,Syiemlieh, Ibanphylla,Asthana,Lal, Ram A.
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- Synthesis and Comparative Catalytic Study of Zirconia–MnCO3 or –Mn2O3 for the Oxidation of Benzylic Alcohols
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We report on the synthesis of the zirconia–manganese carbonate ZrOx(x %)–MnCO3 catalyst (where x=1–7) that, upon calcination at 500 °C, is converted to zirconia–manganese oxide ZrOx(x %)–Mn2O3. We also present a comparative study of the catalytic performance of the both catalysts for the oxidation of benzylic alcohol to corresponding aldehydes by using molecular oxygen as the oxidizing agent. ZrOx(x %)–MnCO3 was prepared through co-precipitation by varying the amounts of Zr(NO3)4 (w/w %) in Mn(NO3)2. The morphology, composition, and crystallinity of the as-synthesized product and the catalysts prepared upon calcination were studied by using scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and powder X-ray diffraction. The surface areas of the catalysts [133.58 m2 g?1 for ZrOx(1 %)–MnCO3 and 17.48 m2 g?1 for ZrOx(1 %)–Mn2O3] were determined by using the Brunauer–Emmett–Teller method, and the thermal stability was assessed by using thermal gravimetric analysis. The catalyst with composition ZrOx(1 %)–MnCO3 pre-calcined at 300 °C exhibited excellent specific activity (48.00 mmolg?1 h?1) with complete conversion within approximately 5 min and catalyst cyclability up to six times without any significant loss in activity. The specific activity, turnover number and turnover frequency achieved is the highest so far (to the best of our knowledge) compared to the previously reported catalysts used for the oxidation of benzyl alcohol. The catalyst showed selectivity for aromatic alcohols over aliphatic alcohols.
- Assal, Mohamed E.,Kuniyil, Mufsir,Khan, Mujeeb,Al-Warthan, Abdulrahman,Siddiqui, Mohammed Rafiq H.,Tremel, Wolfgang,Nawaz Tahir, Muhammad,Adil, Syed Farooq
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p. 112 - 120
(2017/02/10)
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- Efficient and Highly Selective Solvent-Free Oxidation of Primary Alcohols to Aldehydes Using Bucky Nanodiamond
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Selective oxidation of alcohols to aldehydes is widely applicable to the synthesis of various green chemicals. The poor chemoselectivity for complicated primary aldehydes over state-of-the-art metal-free or metal-based catalysts represents a major obstacle for industrial application. Bucky nanodiamond is a potential green catalyst that exhibits excellent chemoselectivity and cycling stability for the selective oxidation of primary alcohols in diverse structures (22 examples, including aromatic, substituted aromatic, unsaturated, heterocyclic, and linear chain alcohols) to their corresponding aldehydes. The results are comparable to reported transition-metal catalysts including conventional Pt/C and Ru/C catalysts for certain substrates under solvent-free conditions. The possible activation process of the oxidant and substrates by the surface oxygen groups and defect species are revealed with model catalysts, ex situ electrochemical measurements, and ex situ attenuated total reflectance. The zigzag edges of sp2 carbon planes are shown to play a key role in these reactions.
- Lin, Yangming,Wu, Kuang-Hsu Tim,Yu, Linhui,Heumann, Saskia,Su, Dang Sheng
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p. 3497 - 3505
(2017/09/15)
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- Synthesis, Characterization, and Relative Study on the Catalytic Activity of Zinc Oxide Nanoparticles Doped MnCO3, -MnO2, and -Mn2O3 Nanocomposites for Aerial Oxidation of Alcohols
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Zinc oxide nanoparticles doped manganese carbonate catalysts [X% ZnOx-MnCO3] (where X = 0-7) were prepared via a facile and straightforward coprecipitation procedure, which upon different calcination treatments yields different manganese oxides, that is, [X% ZnOx-MnO2] and [X% ZnOx-Mn2O3]. A comparative catalytic study was conducted to evaluate the catalytic efficiency between carbonates and oxides for the selective oxidation of secondary alcohols to corresponding ketones using molecular oxygen as a green oxidizing agent without using any additives or bases. The prepared catalysts were characterized by different techniques such as SEM, EDX, XRD, TEM, TGA, BET, and FTIR spectroscopy. The 1% ZnOx-MnCO3 calcined at 300°C exhibited the best catalytic performance and possessed highest surface area, suggesting that the calcination temperature and surface area play a significant role in the alcohol oxidation. The 1% ZnOx-MnCO3 catalyst exhibited superior catalytic performance and selectivity in the aerial oxidation of 1-phenylethanol, where 100% alcohol conversion and more than 99% product selectivity were obtained in only 5 min with superior specific activity (48 mmol·g-1·h-1) and 390.6 turnover frequency (TOF). The specific activity obtained is the highest so far (to the best of our knowledge) compared to the catalysts already reported in the literatures used for the oxidation of 1-phenylethanol. It was found that ZnOx nanoparticles play an essential role in enhancing the catalytic efficiency for the selective oxidation of alcohols. The scope of the oxidation process is extended to different types of alcohols. A variety of primary, benzylic, aliphatic, allylic, and heteroaromatic alcohols were selectively oxidized into their corresponding carbonyls with 100% convertibility without overoxidation to the carboxylic acids under base-free conditions.
- Assal, Mohamed E.,Kuniyil, Mufsir,Shaik, Mohammed Rafi,Khan, Mujeeb,Al-Warthan, Abdulrahman,Siddiqui, Mohammed Rafiq H.,Adil, Syed Farooq
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- A highly reduced graphene oxide/ZrOx-MnCO3 or -Mn2O3 nanocomposite as an efficient catalyst for selective aerial oxidation of benzylic alcohols
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Highly reduced graphene oxide (HRG) nanocomposites of manganese carbonate doped with (1%) zirconia (ZrOx) nanoparticles [ZrOx(1%)-MnCO3/(X%)HRG (where X = 0-7)] were prepared employing a facile coprecipitation method in which the percentage of HRG was varied. The resulting nanocomposite was calcined at 300°C. Further calcination of the catalyst at 500°C resulted in the conversion of manganese carbonate to manganese oxide [ZrOx(1%)-Mn2O3/(X%)HRG]. The effect of the inclusion of HRG on the catalytic activity along with its comparative performance between carbonates and their respective oxides was studied for the liquid-phase selective oxidation of benzylic alcohols into corresponding aldehydes using molecular oxygen as the eco-friendly oxidizing agent without adding any external additives or bases. The influence of different parameters such as different percentages of HRG, reaction times, calcination temperatures, catalyst dosages and reaction temperatures have also been systematically studied in order to optimize the catalyst composition and reaction conditions. The inclusion of HRG as a dopant remarkably enhanced the catalytic efficiency of ZrOx-MnCO3 nanocatalysts for the aerobic oxidation of alcohols. The as-prepared catalysts were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), thermal gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) surface area analysis, Raman spectroscopy and Fourier transform infrared spectroscopy (FT-IR). The catalyst with composition ZrOx(1%)-MnCO3/(1%)HRG obtained by calcination at 300°C exhibited excellent specific activity (60.0 mmol g-1 h-1) with 100% benzyl alcohol conversion and more than 99% product selectivity within an extremely short time (4 min). The same catalyst is employed for the oxidation of a wide range of substituted benzylic and aliphatic alcohols. The catalyst i.e. ZrOx(1%)-MnCO3/(1%)HRG calcined at 300°C yielded corresponding aldehydes with complete convertibility and selectivity in short reaction times under mild conditions whereas the as-prepared catalyst exhibited high selectivity for aromatic alcohols over aliphatic alcohols. The catalyst was recycled and reused at least five times without any obvious loss in its activity or selectivity.
- Assal, Mohamed E.,Shaik, Mohammed Rafi,Kuniyil, Mufsir,Khan, Mujeeb,Al-Warthan, Abdulrahman,Siddiqui, Mohammed Rafiq H.,Khan, Sohail M. A.,Tremel, Wolfgang,Tahir, Muhammad Nawaz,Adil, Syed Farooq
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p. 55336 - 55349
(2018/04/05)
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- A 2, 3, 4-trimethoxybenzene process for the preparation of formaldehyde
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The invention relates to a method for preparing 2, 3, 4-trimethoxybenzaldehyde which is a medical intermediate. The method includes that a coking gallic acid is utilized as a raw material, dimethyl sulfate is utilized as an alkylate reagent, under the condition of existence of sodium hydroxide, methylation is performed through an O-alkylation reaction to obtain an intermediate 1, 2, 3-trimethoxybenzene, and the 1 ,2, 3-trimethoxybenzene and a Vilsmeier-Haack reagent are subjected to a formylation reaction to obtain the 2, 3, 4-trimethoxybenzaldehyde. The method for preparing the 2, 3, 4-trimethoxybenzaldehyde has the advantages that the product purity is above 99%, the total yield reaches to 73%, raw materials are easy to obtain, and the method is suitable for industrial production.
- -
-
Paragraph 0010; 0021; 0023
(2017/02/09)
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- Synthesis and biological evaluation of Hydrazone derivatives as antifungal agents
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Emerging yeasts are among the most prevalent causes of systemic infections with high mortality rates and there is an urgent need to develop specific, effective and non-Toxic antifungal agents to respond to this issue. In this study 35 aldehydes, hydrazones and hydrazines were obtained and their antifungal activity was evaluated against Candida species (C. parapsilosis, C.Tropicalis, C. krusei, C. albicans, C. glabrata and C. lusitaneae) and Trichosporon asahii, in an in vitro screening. The minimum inhibitory concentrations (MICs) of the active compounds in the screening was determined against 10 clinical isolates of C. parapsilosis and 10 of T. asahii. The compounds 4-pyridin-2-ylbenzaldehyde] (13a) and tert-butyl-(2Z)-2-(3,4,5-Trihydroxybenzylidine)hydrazine carboxylate (7b) showed the most promising MIC values in the range of 16-32 μg/mL and 8-16 μg/mL, respectively. The compounds' action on the stability of the cell membrane and cell wall was evaluated, which suggested the action of the compounds on the fungal cell membrane. Cell viability of leukocytes and an alkaline comet assay were performed to evaluate the cytotoxicity. Compound 13a was not cytotoxic at the active concentrations. These results support the discovery of promising candidates for the development of new antifungal agents.
- Casanova, Bruna B.,Muniz, Mauro N.,De Oliveira, Thayse,De Oliveira, Luís Flavio,Machado, Michel M.,Fuentefria, Alexandre M.,Gosmann, Grace,Gnoatto, Simone C. B.
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p. 9229 - 9241
(2016/08/31)
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- Formation and characterization of a reactive chromium(V)-oxo complex: Mechanistic insight into hydrogen-atom transfer reactions
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A mononuclear Cr(V)-oxo complex, [CrV(O)(6-COO--tpa)](BF4)2 (1; 6-COO--tpa = N,N-bis(2-pyridylmethyl)-N-(6-carboxylato-2-pyridylmethyl)amine) was prepared through the reaction of a Cr(III) precursor complex with iodosylbenzene as an oxidant. Characterization of 1 was achieved using ESI-MS spectrometry, electron paramagnetic resonance, UV-vis, and resonance Raman spectroscopies. The reduction potential (Ered) of 1 was determined to be 1.23 V vs. SCE in acetonitrile based on analysis of the electron-transfer (ET) equilibrium between 1 and a one-electron donor, [RuII(bpy)3]2+ (bpy = 2,2′-bipyridine). The reorganization energy (λ) of 1 was also determined to be 1.03 eV in ET reactions from phenol derivatives to 1 on the basis of the Marcus theory of ET. The smaller λ value in comparison with that of an Fe(IV)-oxo complex (2.37 eV) is caused by the small structural change during ET due to the dπ character of the electron-accepting LUMO of 1. When benzyl alcohol derivatives (R-BA) with different oxidation potentials were employed as substrates, corresponding aldehydes were obtained as the 2e--oxidized products in moderate yields as determined from 1H NMR and GC-MS measurements. One-step UV-vis spectral changes were observed in the course of the oxidation reactions of BA derivatives by 1 and a kinetic isotope effect (KIE) was observed in the oxidation reactions for deuterated BA derivatives at the benzylic position as substrates. These results indicate that the rate-limiting step is a concerted proton-coupled electron transfer (PCET) from substrate to 1. In sharp contrast, in the oxidation of trimethoxy-BA (Eox = 1.22 V) by 1, trimethoxy-BA radical cation was observed by UV-vis spectroscopy. Thus, it was revealed that the mechanism of the oxidation reaction changed from one-step PCET to stepwise ET-proton transfer (ET/PT), depending on the redox potentials of R-BA.
- Kotani, Hiroaki,Kaida, Suzue,Ishizuka, Tomoya,Sakaguchi, Miyuki,Ogura, Takashi,Shiota, Yoshihito,Yoshizawa, Kazunari,Kojima, Takahiko
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p. 945 - 955
(2015/02/05)
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- Design and synthesis of 3,3′-biscoumarin-based c-Met inhibitors
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A library of biscoumarin-based c-Met inhibitors was synthesized, based on optimization of 3,3′-biscoumarin hit 3, which was identified as a non-ATP competitive inhibitor of c-Met from a diverse library of coumarin derivatives. Among these compounds, 38 and 40 not only showed potent enzyme activities with IC50 values of 107 nM and 30 nM, respectively, but also inhibited c-Met phosphorylation in BaF3/TPR-Met and EBC-1 cells. This journal is the Partner Organisations 2014.
- Xu, Jimin,Ai, Jing,Liu, Sheng,Peng, Xia,Yu, Linqian,Geng, Meiyu,Nan, Fajun
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p. 3721 - 3734
(2014/06/09)
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- Total synthesis and RXRα-mediated transcription studies of neriifolone B and related compounds
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Neriifolone B (1), a natural product containing a novel 4′,4′-dimethyl-4′,5′-dihydropyran-6-one[2′, 3′:3,4]xanthone skeleton, was found to be a potent inhibitor of transcription mediated by retinoid X receptor α (RXRα). The first total synthesis of neriifolone B (1) was achieved in 14 steps with an overall yield of 7.1%. A Claisen rearrangement was employed as the key step in the sequence. The activity of six natural xanthones and eight compounds related to neriifolone B (1) against RXRα-mediated transcription was evaluated. Two neriifolone B analogs, 17 and 11″, were potent inhibitors of RXRα transcriptional activity. Preliminary structure-activity relationship studies are discussed briefly.
- Shen, Qirong,Dai, Yi,Wang, Guanghui,Yao, Fei,Duan, Yinghui,Chen, Haifeng,Zhang, Weige,Zhang, Xiaokun,Yao, Xinsheng
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p. 2671 - 2677
(2014/05/06)
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- Aerobic oxidation of alcohols by using a completely metal-free catalytic system
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A metal-free reaction system of air, NH4NO3(cat), 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)(cat), and H +(cat) is introduced as a simple, safe, inexpensive, efficient and chemoselective mediator for aerobic oxidation of various primary and secondary benzyl and alkyl alcohols, including those bearing oxidizable heteroatoms (N, S, O) to the corresponding aldehydes or ketones. Air oxygen under slight overpressure plays the role of the terminal oxidant, which is catalytically activated by redox cycles of nitrogen oxides released from a catalytic amount of NH4NO3 and cocatalyzed by TEMPO (nitroxyl radical compound), under acidic conditions, which are essential for an overall activation of the reaction system. The synthetic value of this reaction system and its green chemical profile was illustrated by a 10 g scale-up experiment, performed in an open-air system by using a renewable and reusable polymer-supported form of TEMPO (OXYNITROXS100). The reaction solvent was recovered by distillation under atmospheric pressure, and the pure final product was isolated under reduced pressure; the acid activators (HCl or H 2SO4) were recovered as ammonium salts. A metal-free reaction system of air/NH4NO3(cat)/TEMPO (cat)/H+(cat) is introduced as a simple, safe, inexpensive, efficient and chemoselective mediator for aerobic oxidation of various primary and secondary benzyl, alkyl and allyl alcohols, including those bearing oxidizable heteroatoms (N, S, O) to the corresponding aldehydes or ketones. Copyright
- Prebil, Rok,Stavber, Gaj,Stavber, Stojan
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supporting information
p. 395 - 402
(2014/01/23)
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- Aerobic Oxidation of Alcohols by Using a Completely Metal-Free Catalytic System
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A metal-free reaction system of air, NH4NO3(cat), 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)(cat), and H+(cat) is introduced as a simple, safe, inexpensive, efficient and chemoselective mediator for aerobic oxidation of various primary and secondary benzyl and alkyl alcohols, including those bearing oxidizable heteroatoms (N, S, O) to the corresponding aldehydes or ketones. Air oxygen under slight overpressure plays the role of the terminal oxidant, which is catalytically activated by redox cycles of nitrogen oxides released from a catalytic amount of NH4NO3 and cocatalyzed by TEMPO (nitroxyl radical compound), under acidic conditions, which are essential for an overall activation of the reaction system. The synthetic value of this reaction system and its green chemical profile was illustrated by a 10 g scale-up experiment, performed in an open-air system by using a renewable and reusable polymer-supported form of TEMPO (OXYNITROXS100). The reaction solvent was recovered by distillation under atmospheric pressure, and the pure final product was isolated under reduced pressure; the acid activators (HCl or H2SO4) were recovered as ammonium salts.
- Prebil, Rok,Stavber, Gaj,Stavber, Stojan
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supporting information
p. 395 - 402
(2015/10/05)
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- Solid supported Ru(0) nanoparticles: An efficient ligand-free heterogeneous catalyst for aerobic oxidation of benzylic and allylic alcohol to carbonyl
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Polymer immobilized stable, spherical ruthenium nanoparticles were prepared, characterized, and acted as a heterogeneous catalyst for the selective benzylic and allylic alcohol oxidation into the corresponding carbonyls using molecular oxygen. The solid supported Ru(0) (SS-Ru) as a heterogeneous catalyst exhibits good reusability and easy separation from the reaction mixture by filtration.
- Das, Pralay,Aggarwal, Nidhi,Guha, Nitul Ranjan
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supporting information
p. 2924 - 2928
(2013/06/27)
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- PET imaging of nobiletin based on a practical total synthesis
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A practical synthesis of nobiletin, a polymethoxylated citrus flavone, was accomplished by utilizing our novel flavone synthesis. Synthetic nobiletin was labelled by selective demethylation and rapid incorporation of 11C atom. Positron emission tomography images successfully visualized the brain distribution, which may provide therapeutic benefits in the treatment of Alzheimer's disease. The Royal Society of Chemistry.
- Asakawa, Tomohiro,Hiza, Aiki,Nakayama, Miho,Inai, Makoto,Oyama, Dai,Koide, Hiroyuki,Shimizu, Kosuke,Wakimoto, Toshiyuki,Harada, Norihiro,Tsukada, Hideo,Oku, Naoto,Kan, Toshiyuki
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supporting information; experimental part
p. 2868 - 2870
(2011/04/22)
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- Tandem allylic oxidation-condensation/esterification catalyzed by silica gel: An expeditious approach towards antimalarial diaryldienones and enones from natural methoxylated phenylpropenes
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A new one-pot strategy has been developed, wherein abundantly available methoxylated phenylpropenes are directly transformed into corresponding dienones (1,5-diarylpenta-2,4-dien-1-ones) and enones (chalcones and cinnamic esters) via allylic oxidation-condensation or allylic oxidation-esterification sequences. Preliminary antimalarial activity studies of the above synthesized diaryldienones and enones against Plasmodium falciparum (Pf3D7) have shown them to be promising lead candidates for developing newer and economical antimalarial agents. In particular, two enones (12b and 13b) were found to possess comparatively better activity (IC50 = 4.0 and 3.4 μM, respectively) than licochalcone (IC50 = 4.1 μM), a well known natural antimalarial compound. The Royal Society of Chemistry 2011.
- Sharma, Abhishek,Sharma, Naina,Shard, Amit,Kumar, Rakesh,Mohanakrishnan, Dinesh,Saima,Sinha, Arun K.,Sahal, Dinkar
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supporting information; experimental part
p. 5211 - 5219
(2011/08/07)
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- Oxidation of alcohols with molecular oxygen promoted by Nafion ionomer anchored pyrochlore composite at room temperature
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Nafion ionomer anchored ruthenium oxide pyrochlore composite has been demonstrated for selective oxidation of alcohols to aldehydes and ketones in good yields. In the absence of any additives, the reaction was achieved by atmospheric air or molecular oxygen at room temperature.
- Venkatesan,Kumar, A. Senthil,Zen
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p. 4339 - 4341
(2008/12/21)
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- An efficient biomimetic cleavage of gem-diacetates to aldehydes by β-cyclodextrin under neutral conditions in aqueous medium
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The cleavage of gem-diacetates to aldehydes, a widely used protecting group in organic synthesis, has been achieved for the first time under neutral conditions in aqueous medium using β-cyclodextrin as catalyst. The main advantage of the present methodology is that it can be used with compounds having a variety of functional groups since the cleavage is carriedout under neutral conditions in aqueous medium.
- Arjun Reddy,Rajender Reddy,Bhanumathi,Rama Rao
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p. 273 - 277
(2007/10/03)
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- Oxidation of oximes to ketones with zeolite supported permanganate
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A variety of aldoximes and ketoximes are oxidised to corresponding aldehydes and ketones in excellent yields by zeolite supported permanganate.
- Jadhav,Wadgaonkar,Joshi,Salunkhe
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p. 1989 - 1995
(2007/10/03)
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- Phenol compound having antioxidative activity and the process for preparing the same
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Disclosed are a phenol compound represented by the formula (1): STR1 wherein R0 represents H, alkyl or alkyloxy; R1 represents alkyl; R2 represents alkyl or alkyloxy; OR3 represents OH; R4 represents H, lower alkyl or acyl, each of the above substituents may be substituted; W represents O, S or NR7 ; where R7 represents H, alkyl, aryl, OH or alkyloxy, a group of the formula (2): STR2 represents an amino which may be mono- or di-substituted or heterocyclic group containing N atom, or a pharmaceutically acceptable salt thereof, and a process for preparing the same.
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- Manganese(III)-Mediated Formylation of Aromatic Compounds in the Presence of Malonic Acid
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The reaction of naphthlenes with malonic acid in the presence of manganese(III) acetate gives naphthalenecarbaldehydes and naphthalenecarboxylic acids.Similar reactions of anthracene, pyrene, and methoxybenzenes also yield formylated and carboxylated products.It was found that the formyl group introduced to the aromatic ring was not derived from carboxymethyl radical generated directly by the thermolysis of manganese(III) acetate, but from a dicarboxymethyl radical formed by the interaction of malonic acid and manganese(III) acetate.In addition, it was also found that the dicarboxymethyl radicals attacked the position of the highest electron density on the aromatic ring and that this formylation was effective when the ionization potential of the aromatic copound was lower than 7.8 eV.
- Nishino, Hiroshi,Tsunoda, Katsunori,Kurosawa, Kazu
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p. 545 - 550
(2007/10/02)
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- 3-METHOXYBENZYL (3-MPM) AND 3,5-DIMETHOXYBENZYL (3,5-DMPM) PROTECTING GROUPS FOR THE HYDROXY FUCTION LESS READILY REMOVABLE THAN 4-METHOXYBENZYL (MPM) AND 3,4-DIMETHOXYBENZYL (DMPM) PROTECTING GROUPS BY DDQ OXIDATION
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New protecting groups for the hydroxy fuction, 3-methoxybenzyl (3-MPM) and 3,5-dimethoxybenzyl (3,5-DMPM) groups are slowly removed by DDQ oxidation at room temperature and distinguished from readily removable 4-methoxybenzyl (MPM).They are stable to strong acids.KEYWORDS-- protecting group; hydroxy function; DDQ oxidation; selective deprotection; 3-methoxybenzyl; 3,5-dimethoxybenzyl
- Nakajima, Noriyuki,Abe, Reiko,Yonemitsu, Osamu
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p. 4244 - 4247
(2007/10/02)
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- 3-(substituted phenyl)phthalides
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Process comprises the combination of the three steps of condensing 3-N(R)2 -4-X-benzoic acid with an aromatic or heterocyclic aldehyde, Y-CHO, under acidic conditions to produce 3-Y-5-X-6-N(R)2 phthalide (II), condensing said phthalide with a compound of the formula Z-H under alkaline or acid conditions to produce 2-(α-Y-α-Z)methyl-4-X-5-N(R)2 benzoic acid (III), and oxidizing said benzoic acid to produce 3-Y-3-Z-5-X-6-N(R)2 phthalide (I) where: R is hydrogen, non-tertiary alkyl of one to four carbon atoms, benzyl or substituted benzyl; X is hydrogen or halo; Y is 4-R1 -3-R2 -2-R1 -phenyl, 1-R5 -2-R6 -5/6-R4 -3-indolyl, 9-R7 -3-carbazolyl, 9-julolidinyl, 3,4-dioxymethylenephenyl, 2-thienyl, 1-R8 -2-pyrrolyl, or 4-pyridinyl; and Z is 4-R1 -3-R2 -2-R1 -phenyl, 1-R5 -2-R6 -5/6-R4 -3-indolyl or 1-R8 -2-pyrrolyl which are useful as colorless precursor color formers in carbonless duplicating and in thermal marking systems. The intermediates, 3-Y-5-X-6-N(R)2 phthalides (II) and 2-(α-Y-α-Z)methyl-4-X-5-N(R)2 benzoic acids (III) also have utility as colorless precursor color formers in carbonless duplicating and thermal marking systems.
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