- Negative correlations between cultivable and active-yet-uncultivable pyrene degraders explain the postponed bioaugmentation
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Bioaugmentation is an effective approach to remediate soils contaminated by polycyclic aromatic hydrocarbons (PAHs), but suffers from unsatisfactory performance in engineering practices, which is hypothetically explained by the complicated interactions between indigenous microbes and introduced degraders. This study isolated a cultivable pyrene degrader (Sphingomonas sp. YT1005) and an active pyrene degrading consortium (Gp16, Streptomyces, Pseudonocardia, Panacagrimonas, Methylotenera and Nitrospira) by magnetic-nanoparticle mediated isolation (MMI) from soils. Pyrene biodegradation was postponed in bioaugmentation with Sphingomonas sp. YT1005, whilst increased by 30.17% by the active pyrene degrading consortium. Pyrene dioxygenase encoding genes (nidA, nidA3 and PAH-RHDα-GP) were enriched in MMI isolates and positively correlated with pyrene degradation efficiency. Pyrene degradation by Sphingomonas sp. YT1005 only followed the phthalate pathway, whereas both phthalate and salicylate pathways were observed in the active pyrene degrading consortium. The results indicated that the uncultivable pyrene degraders were suitable for bioaugmentation, rather than cultivable Sphingomonas sp. YT1005. The negative correlations between Sphingomonas sp. YT1005 and the active-yet-uncultivable pyrene degraders were the underlying mechanisms of bioaugmentation postpone in engineering practices.
- Jiang, Bo,Chen, Yating,Xing, Yi,Lian, Luning,Shen, Yaoxin,Zhang, Baogang,Zhang, Han,Sun, Guangdong,Li, Junyi,Wang, Xinzi,Zhang, Dayi
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- A functional model for quercetin 2,4-dioxygenase: Geometric and electronic structures and reactivity of a nickel(II) flavonolate complex
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Quercetin 2,4-dioyxgenase (QueD) has been known to catalyze the oxygenative degradation of flavonoids and quercetin. Recent crystallographic study revealed a nickel ion occupies the active site as a co-factor to support O2 activation and catalysis. Herein, we report a nickel(II) flavonolate complex bearing a tridentate macrocyclic ligand, [NiII(Me3-TACN)(Fl)(NO3)](H2O) (1, Me3-TACN = 1,4,7-trimethyl-1,4,7-triazacyclononane, Fl = 3-hydroxyflavone) as a functional model for QueD. The flavonolatonickel(II) complex was characterized by using spectrometric analysis including UV–vis spectroscopy, electrospray ionization mass spectrometer (ESI-MS), infrared spectroscopy (FT-IR) and 1H nuclear magnetic resonance spectroscopy (NMR). The single crystal X-ray structure of 1 shows two isomers with respect to the direction of a flavonolate ligand. Two isomers commonly are in the octahedral geometry with a bidentate of flavonolate and a monodentate of nitrate as well as a tridentate binding of Me3-TACN ligand. The spin state of 1 is determined to be a triplet state based on the Evans' method. Interestingly, electronic configuration of 1 from density functional theory (DFT) calculations revealed that the two singly occupied molecular orbitals (SOMOs) lie energetically lower than the highest (doubly) occupied molecular orbital (HOMO), that is so-called the SOMO-HOMO level inversion (SHI). The HOMO shows an electron density localized in the flavonolate ligand, indicating that flavonolate ligand is oxidized first rather than the nickel center. Thermal degradation of 1 resulted in the formation of benzoic acid and salicylic acid, which is attributed to the oxygenation of flavonolate of 1.
- Jeong, Donghyun,Sun, Seungwon,Moon, Dohyun,Cho, Jaeheung
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- Synthesis of salicylates from anionically activated aromatic trifluoromethyl group
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An efficient approach to salicylates via a novel transformation of anionically activated aromatic trifluoromethyl group is described. Anionically activated trifluoromethyl group can react with phenols/alcohols under alkaline conditions to afford aryl/alkyl salicylates in high yields. Mechanism studies indicate that the carbonyl oxygen atom of ester is from the H2O in the solvent.
- Lin, Chuankai,Liu, Jin-Biao,Wang, Ruixiang,Xie, Huilin
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supporting information
(2021/12/22)
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- N,O-bidentate ligands-based salicylic spiroborates: A bright frontier of bioimaging
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A new series of salicylic spiroborate complexes (SSBs) based on N,O-bidentate 2-(tert-cycloalkylamino)-5-(3-(arylamino)acryloyl)thiophene-3-carbonitriles (NO-SSBs) was obtained and characterized. The optical properties of these compounds were studied and compared with those of analogous BF2-based complexes. The geometries and electronic structures of the NO-SSBs in the ground and excited states, especially their key N–B–O link, were revealed using quantum chemical calculations and compared with the experimental data and photophysical characteristics. Hydrolytic dissociation and photodissociation were considered, and the effects of the NO-SSB structure and nature of the solvent on these reactions were established. Biological investigations elucidated the NO-SSBs ability to penetrate living and fixed cells and selectively accumulate in the endoplasmic reticulum (ER) and Golgi complex. Comparison of the NO-SSBs’ characteristics with those of a commercial dye demonstrated the superiority of their properties and prospects for application in the bio-visualization of the ER and Golgi complex.
- Belskaya, Nataliya P.,Benassi, Enrico,Fomin, Timur O.,Lugovik, Kseniya I.,Minin, Artem S.,Pozdina, Varvara A.,Shevyrin, Vadim A.
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- Oxygenolysis of a series of copper(ii)-flavonolate adducts varying the electronic factors on supporting ligands as a mimic of quercetin 2,4-dioxygenase-like activity
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Four copper(ii)-flavonolate compounds of type [Cu(LR)(fla)] {where LR = 2-(p-R-benzyl(dipyridin-2-ylmethyl)amino)acetate; R = -OMe (1), -H (2), -Cl (3) and -NO2 (4)} have been developed as a structural and functional enzyme-substrate (ES) model of the Cu2+-containing quercetin 2,4-dioxygenase enzyme. The ES model complexes 1-4 are synthesized by reacting 3-hydroxyflavone in the presence of a base with the respective acetate-bound copper(ii) complexes, [Cu(LR)(OAc)]. In the presence of dioxygen the ES model complexes undergo enzyme-type oxygenolysis of flavonolate (dioxygenase type bond cleavage reaction) at 80 °C in DMF. The reactivity shows a substituent group dependent order as -OMe (1) > -H (2) > -Cl (3) > ?NO2 (4). Experimental and theoretical studies suggest a single-electron transfer (SET) from flavonolate to dioxygen, rather than valence tautomerism {[CuII(fla?)] ? [CuI(fla˙)]}, to generate the reactive flavonoxy radical (fla˙) that reacts further with the superoxide radical to bring about the oxygenative ring opening reaction. The SET pathway has been further verified by studying the dioxygenation reaction with a redox-inactive Zn2+ complex, [Zn(LOMe)(fla)] (5).
- Anoop, Anakuthil,Dey, Subhasis,Mandal, Sukanta,Podder, Nirmalya
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supporting information
p. 4338 - 4353
(2022/04/07)
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- Practical scale up synthesis of carboxylic acids and their bioisosteres 5-substituted-1H-tetrazoles catalyzed by a graphene oxide-based solid acid carbocatalyst
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Herein, catalytic application of a metal-free sulfonic acid functionalized reduced graphene oxide (SA-rGO) material is reported for the synthesis of both carboxylic acids and their bioisosteres, 5-substituted-1H-tetrazoles. SA-rGO as a catalytic material incorporates the intriguing properties of graphene oxide material with additional benefits of highly acidic sites due to sulfonic acid groups. The oxidation of aldehydes to carboxylic acids could be efficiently achieved using H2O2as a green oxidant with high TOF values (9.06-9.89 h?1). The 5-substituted-1H-tetrazoles could also be effectively synthesized with high TOF values (12.08-16.96 h?1). The synthesis of 5-substituted-1H-tetrazoles was corroborated by single crystal X-ray analysis and computational calculations of the proposed reaction mechanism which correlated well with experimental findings. Both of the reactions could be performed efficiently at gram scale (10 g) using the SA-rGO catalyst. SA-rGO displays eminent reusability up to eight runs without significant decrease in its productivity. Thus, these features make SA-rGO riveting from an industrial perspective.
- Mittal, Rupali,Kumar, Amit,Awasthi, Satish Kumar
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p. 11166 - 11176
(2021/03/31)
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- Cleavage of Carboxylic Esters by Aluminum and Iodine
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A one-pot procedure for deprotecting carboxylic esters under nonhydrolytic conditions is described. Typical alkyl carboxylates are readily deblocked to the carboxylic acids by the action of aluminum powder and iodine in anhydrous acetonitrile. Cleavage of lactones affords the corresponding ω-iodoalkylcarboxylic acids. Aryl acetylates undergo deacetylation with the participation of the neighboring group. This method enables the selective cleavage of alkyl carboxylic esters in the presence of aryl esters.
- Sang, Dayong,Yue, Huaxin,Fu, Yang,Tian, Juan
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p. 4254 - 4261
(2021/03/09)
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- Understanding Methyl Salicylate Hydrolysis in the Presence of Amino Acids
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Methyl salicylate, the major flavor component in wintergreen oil, is commonly used as food additives. It was found that amino acids can unexpectedly expedite methyl salicylate hydrolysis in an alkaline environment, while the detailed mechanism of this reaction merits investigation. Herein, the role of amino acid, more specifically, glycine, in methyl salicylate hydrolysis in aqueous solution was explored. 1H NMR spectroscopy, combined with density functional theory calculations, was employed to investigate the methyl salicylate hydrolysis in the presence and absence of glycine at pH 9. The addition of glycine was found to accelerate the hydrolysis by an order of magnitude at pH 9, compared to that at pH 7. The end hydrolyzed product was confirmed to be salicylic acid, suggesting that glycine does not directly form an amide bond with methyl salicylate via aminolysis. Importantly, our results indicate that the ortho-hydroxyl substituent in methyl salicylate is essential for its hydrolysis due to an intramolecular hydrogen bond, and the carboxyl group of glycine is crucial to methyl salicylate hydrolysis. This study gains a new understanding of methyl salicylate hydrolysis that will be helpful in finding ways of stabilizing wintergreen oil as a flavorant in consumer food products that also contain amino acids.
- Cheng, Chi-Yuan,Brinzari, Tatiana V.,Hao, Zhigang,Wang, Xiaotai,Pan, Long
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p. 6013 - 6021
(2021/06/25)
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- Electrochemical-induced hydroxylation of aryl halides in the presence of Et3N in water
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A thorough study of mild and environmentally friendly electrochemical-induced hydroxylation of aryl halides without a catalyst is presented. The best protocol consists of hydroxylation of different aryl iodides and aryl bromides by water solution in the presence of Et3N under air, affording the target phenols in good isolated yields. Moreover, aryl chlorides were successfully employed as substrates. This methodology also provides a direct pathway for the formation of deoxyphomalone, which displayed a significant anti-proliferation effect.
- Ke, Fang,Lin, Chen,Lin, Mei,Long, Hua,Wu, Mei,Yang, Li,Zhuang, Qinglong
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supporting information
p. 6417 - 6421
(2021/08/03)
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- Photocatalytic synthesis of phenols mediated by visible light using KI as catalyst
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A transition-metal-free hydroxylation of iodoarenes to afford substituted phenols is described. The reaction is promoted by KI under white LED light irradiation and uses atmospheric oxygen as oxidant. By the use of triethylamine as base and solvent, the corresponding phenols are obtained in moderate to good yields. Mechanistic studies suggest that KI and catalysis synergistically promote the cleavage of C-I bond to form free aryl radicals.
- Huiqin, Wei,Wu, Mei
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supporting information
(2021/11/30)
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- An efficient chromium(iii)-catalyzed aerobic oxidation of methylarenes in water for the green preparation of corresponding acids
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A highly efficient method to oxidize methylarenes to their corresponding acids with a reusable Cr catalyst was developed. The reaction can be carried out in water with 1 atm oxygen and K2S2O8as cooxidants, proceeds under green and mild conditions, and is suitable for the oxidation of both electron-deficient and electron-rich methylarenes, including heteroaryl methylarenes, even at the gram level. The excellent result, together with its simplicity of operation and the ability to continuously reuse the catalyst, makes this new methodology environmentally benign and cost-effective. The generality of this methodology gives it the potential for use on an industrial scale. Differing from the accepted oxidation mechanism of toluene, GC-MS studies and DFT calculations have revealed that the key benzyl alcohol intermediate is formed under the synergetic effect of the chromium and molybdenum in the Cr catalyst, which can be further oxidized to afford benzaldehyde and finally benzoic acid.
- Jiang, Feng,Liu, Shanshan,Wei, Yongge,Yan, Likai,Yu, Han,Zhao, Wenshu
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supporting information
p. 12413 - 12418
(2021/09/28)
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- Cu(II)-Based Ionic Liquid Supported on SBA-15 Nanoparticles Catalyst for the Oxidation of Various Alcohols into Carboxylic Acids in the Presence of CO2
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In this paper, we have produced carboxylic acids by the oxidation of various alcohols in the presence of CO2 using SBA-15/IL supported Cu(II) (SBA-15/IL/Cu(II)) as nanocatalyst. The obtained products showed to have excellent yields by taking into account of SBA-15/IL/Cu(II) nanocatalyst. In addition, the analysis of EDX, SEM, TGA, TEM, XPS, and FT-IR showed the heterogeneous structure of SBA-15/IL/Cu (II) catalyst. It is determined that, after using SBA-15 excess, the catalytic stability of the system was enhanced. Moreover, hot filtration provided a full vision in the heterogeneous catalyst nature. The recycling as well as reuse of the catalyst were studied in cases of coupling reactions many times. Moreover, we have studied the mechanism of the coupling reactions. Graphic Abstract: [Figure not available: see fulltext.]
- Chen, Yanwu,Hou, Dejian,Lin, Litian,Peng, Qi,Sadeghzadeh, Seyed Mohsen
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- A PROCESS FOR SELECTIVE OXIDATION OF ORTHO-CRESOL AND CATALYST THEREOF
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The present invention relates to process for selective oxidation of o-cresol using heterogeneous catalyst. More particularly, the present invention relates to a selectively salicylaldehyde by oxidation of o-cresol, comprising steps of treating o-cresol with heterogeneous catalyst consisting of 3-7 % cobalt doped octahedral molecular sieves (OMS-2) support having Surface area between 80- 140 m2/g and pore size between 5 to 20 nm, the treatment is in presence of methanol and molecular oxygen at temperature between 60-85°C and pressure between 3 to 5 atm for time between 1 to 2 h. The process of present invention is to achieve high yield and conversion at mild reaction conditions.
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Page/Page column 9; 10
(2021/02/12)
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- Efficiency of lithium cations in hydrolysis reactions of esters in aqueous tetrahydrofuran
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Lithium cations were observed to accelerate the hydrolysis of esters with hydroxides (KOH, NaOH, LiOH) in a water/tetrahydrofuran (THF) two-phase system. Yields in the hydrolysis of substituted benzoates and aliphatic esters using the various hydroxides were compared, and the effects of the addition of lithium salt were examined. Moreover, it was presumed that a certain amount of LiOH was dissolved in THF by the coordination of THF with lithium cation and hydrolyzed esters even in the THF layer, as in the reaction by a phase-transfer catalyst.
- Harada, Yumi,Hayashi, Kazuhiko,Ichimaru, Yoshimi,Imai, Masanori,Kojima, Yuki,Maeda, Azusa,Nakayama, Kanae,Sugiura, Kirara
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p. 581 - 594
(2021/06/06)
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- Palladium-catalyzed ortho-C-H hydroxylation of benzoic acids
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A simple Pd(OAc)2 catalyzed ortho-hydroxylation of benzoic acids using TBHP as the sole oxidant has been explored. This protocol features relatively broad substrate scope and operational simplicity. The compatibility of ortho-substituted substrates is an effective complement to the previous ortho-hydroxylation reaction.
- Luo, Feihua,He, Shuhua,Gou, Quan,Chen, Jinyang,Zhang, mingzhong
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- Iron(III) Complex-Functionalized Gold Nanocomposite as a Strategic Tool for Targeted Photochemotherapy in Red Light
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Iron(III)-phenolate/carboxylate complexes exhibiting photoredox chemistry and photoactivated reactive oxygen species (ROS) generation at their ligand-to-metal charge-transfer (LMCT) bands have emerged as potential strategic tools for photoactivated chemotherapy. Herein, the synthesis, in-depth characterization, photochemical assays, and remarkable red light-induced photocytotoxicities in adenocarcinomic human immortalized human keratinocytes (HaCaT) and alveolar basal epithelial (A549) cells of iron(III)-phenolate/carboxylate complex of molecular formula, [Fe(L1)(L2)] (1), where L1 is bis(3,5 di-tert-butyl-2-hydroxybenzyl)glycine and L2 is 5-(1,2-dithiolan-3-yl)-N-(1,10-phenanthroline-5-yl)pentanamide, and the gold nanocomposite functionalized with complex 1 (1-AuNPs) are reported. There was a significant red shift in the UV-visible absorption band on functionalization of complex 1 to the gold nanoparticles (λmax: 573 nm, 1; λmax: 660 nm, 1-AuNPs), rendering the nanocomposite an ideal candidate for photochemotherapeutic applications. The notable findings in our present studies are (i) the remarkable cytotoxicity of the nanocomposite (1-AuNPs) to A549 (IC50: 0.006 μM) and HaCaT (IC50: 0.0075 μM) cells in red light (600-720 nm, 30 J/cm2) while almost nontoxic (IC50 > 500 μg/mL, 0.053 μM) in the dark, (ii) the nontoxicity of 1-AuNPs to normal human diploid fibroblasts (WI-38) or human peripheral lung epithelial (HPL1D) cells (IC50 > 500 μg/mL, 0.053 μM) both in the dark and red light signifying the target-specific anticancer activity of the nanocomposite, (iii) localization of 1-AuNPs in mitochondria and partly nucleus, (iv) remarkable red light-induced generation of reactive oxygen species (ROS: 1O2, ?OH) in vitro, (v) disruption of the mitochondrial membrane due to enhanced oxidative stress, and (vi) caspase 3/7-dependent apoptosis. A similar cytotoxic profile of complex 1 was another key finding of our studies. Overall, our current investigations show a new red light-absorbing iron(III)-phenolate/carboxylate complex-functionalized gold nanocomposite (1-AuNPs) as the emerging next-generation iron-based photochemotherapeutic agent for targeted cancer treatment modality.
- Biswas, Arunima,Kunwar, Amit,Musib, Dulal,Pal, Maynak,Ramu, Vanitha,Roy, Mithun
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supporting information
p. 6283 - 6297
(2021/05/31)
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- Hydrolysis of amides to carboxylic acids catalyzed by Nb2O5
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Hydrolysis of amides to carboxylic acids is an industrially important reaction but is challenging due to the difficulty of cleaving the resonance stabilized amidic C-N bond. Twenty-three heterogeneous and homogenous catalysts were examined in the hydrolysis of acetamide. Results showed that Nb2O5was the most effective heterogeneous catalyst with the greatest yield of acetic acid. A series of Nb2O5catalysts calcined at various temperatures were characterized and tested in the hydrolysis of acetamide to determine the effects of crystal phase and surface properties of Nb2O5on catalytic performance. The high catalytic performance observed was attributed mainly to the facile activation of the carbonyl bond by Lewis acid sites that function even in the presence of basic inhibitors (NH3and H2O). The catalytic studies showed the synthetic advantages of the present method, such as simple operation, catalyst recyclability, additive free, solvent free, and wide substrate scope (>40 examples; up to 95% isolated yield).
- Siddiki,Rashed, Md. Nurnobi,Touchy, Abeda Sultana,Jamil, Md. A. R.,Jing, Yuan,Toyao, Takashi,Maeno, Zen,Shimizu, Ken-Ichi
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p. 1949 - 1960
(2021/03/26)
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- A novel nickel complex with 3-Hydroxyflavone: Synthesis, CrystalStructure and reactivity towards O2 of Ni4(C15O3H9)4(CH3O)4(H2O)4
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A novel tetranuclear nickel(II)-flavonolate complex [NiII4(fla)4(CH3O)4(H2O)4] (flaH: 3-Hydroxyflavone, flavonol) was synthesized. Its crystal structure and spectroscopic features have been investigated in details by physicochemical methods and single crystal X-ray diffraction. Different from other mononuclear metal-flavonolate complexes, this complex demonstrates a cluster molecular structure which has four NiII centers, and each NiII centre is coordinated by a bidentate flavonolate, three methanol and a water molecule. The crystal of this complex is tetragonal crystal system: space group I 41/a, a = 24.4361(14), b = 24.4361(14), c = 12.7972 (14), α = β = γ = 90°, V = 7641.5 (12), Z = 4. The complex can react with O2, in other words, it has enzymatic reactivity just like enzyme-substrate model of quercetin 2,3-dioxygenase, and the reaction products are similar with the other reported enzyme-substrate models.
- Huang, Qian-Qian
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- B-Ring-extended flavonol-based photoCORM: activated by cysteine-ratiometric fluorescence sensing and accurate control of linear CO release
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The first B-ring-extended (to biphenyl) flavonol-based Cys-ratiometric fluorescent probeB-bph-fla-acr(2-([1,1′-biphenyl]-4-yl)-4-oxo-4H-chromen-3-yl acrylate) is developed.B-bph-fla-acrcan ratiometrically sense and non-ratiometrically image endogenous and exogenous cysteine (Cys) in living HeLa cells and zebrafish rapidly (45 s), selectively (vs.homocysteine and glutathione), sensitively (detection limit: 18.5 nM), and with a large Stokes shift (186 nm). Quantitatively released (from the reaction ofB-bph-fla-acrwith Cys) fluorophoreB-bph-fla-OH(2-([1,1′-biphenyl]-4-yl)-3-hydroxy-4H-chromen-4-one) is designed as a photoCORM (photo-triggered CO releasing molecule). Under O2and visible light irradiation, the amount of CO released byB-bph-fla-OHcan be accurately controlled linearly by adjusting the light irradiation intensity, irradiation time, or photoCORM dose. This process is accompanied by fluorescence quenching; therefore, the location of the photoCORM and the CO release process can be monitored in real time.B-bph-fla-acrand all reaction products exhibit good membrane permeability and low toxicity for living HeLa cells. In living HeLa cells and zebrafish,B-bph-fla-acrcan image endogenous and exogenous Cys, and the releasedB-bph-fla-OHcan photo-release CO under O2at room temperature. This study is the first to combine a B-ring-extended flavonol-based fluorescent probe (for the effective ratiometric sensing and non-ratiometric imaging of endogenous and exogenous Cysin vitroandin vivo) with a photoCORM (Cys-activated, visible light-triggered linear CO release under O2). Our study provides important insights into the biological roles of Cys and CO, as well as a reliable method for safely supplying accurately controlled amounts of CO to living systems, thereby facilitating the development of convenient clinical diagnostic molecular tools and therapeutic prodrugs.
- Sun, Ying-Ji,Yu, Chao
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supporting information
p. 8263 - 8271
(2021/10/20)
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- Assessing the photocatalytic activity of europium doped TiO2 using liquid phase plasma process on acetylsalicylic acid
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In this study, europium (Eu) was precipitated in TiO2 powder using liquid phase plasma (LPP) process to prepare a photocatalyst with higher activity, even in the visible light range. Eu was uniformly deposited on the surface of TiO2 by the LPP method. It was observed that the amount of Eu precipitated on the TiO2 surface increased with increasing precursor concentration. XPS and EDS analysis showed that Eu was precipitated as europium oxide. The precipitation of Eu shifted the position of the Raman peak to a higher wavelength; with higher Eu content, the band gap energy decreased. Particularly, the photocatalytic efficiency of the Eu doped TiO2 photocatalyst (EDTP) in the visible light source was much higher than that of bare TiO2, and with higher Eu content, the photocatalytic activity was improved. Acetylsalicylic acid was attacked by HO? produced on the EDTP's surface and assumed to be finally mineralized to H2O and CO2 via two decomposition pathways, namely, decarboxylation and deacetylation.
- Bang, Hye-Jin,Ha, Hyung-Ho,Jung, Sang-Chul,Kim, Sun-Jae,Lee, Heon,Park, Young-Kwon,Yu, Young Hyun
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- Copper and L-(?)-quebrachitol catalyzed hydroxylation and amination of aryl halides under air
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L-(?)-Quebrachitol, a natural product obtained from waste water of the rubber industry, was utilized as an efficient ligand for the copper-catalyzed hydroxylation and amination of aryl halides to selectively give phenols and aryl amines in water or 95percent ethanol. In addition, the hydroxylation of 2-chloro-4-hydroxybenzoic acid was validated on a 100-g scale under air.
- Bao, Xuefei,Chen, Guoliang,Dong, Jinhua,Du, Fangyu,Li, Hui,Liang, Xinjie,Wu, Ying,Zhang, Yongsheng
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supporting information
(2020/08/03)
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- Catalytic oxidation of alcohols and alkyl benzenes to carbonyls using Fe3O4?SiO2?(TEMPO)-: Co -(Chlorophyll-CoIII) as a bi-functional, self-co-oxidant nanocatalyst
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Chlorophyll b was extracted from heliotropium europaeum plant, demetalated, allylated and grafted to acrylated TEMPO through a copolymerization protocol. Then, the chlorophyll monomers were coordinated to Co ions, immobilized on magnetic nanoparticles and the resulting hybrid was used as a powerful catalyst for a variety of oxidation reactions. By using the present method, oxidation of benzylic alcohols and alkyl benzenes to carbonyls was accomplished in water under aerobic conditions. Moreover, direct oxidation of alcohols to carboxylic acids was performed by adding NaOCl to the mixture. All entries were oxidized to the corresponding desired product with high to excellent yields and up to 97% selectivity. The catalyst was thoroughly characterized by CV, TGA, VSM, XRD, XPS, DLS, FE-SEM, TEM, UV-Vis, EDX, and BET analyses. The activity of the catalyst was investigated by applying various components of the catalyst to the oxidation model separately. The reasonable mechanisms are suggested based on the cooperation between the TEMPO groups and cobalt(iii) (or Co(iv)) sites on the catalyst. The catalyst could be recovered and reused for at least 7 consecutive recycles without any considerable reactivity loss. This journal is
- Hamah-Ameen, Baram Ahmed,Kazemnejadi, Milad,Mahmoudi, Boshra,Rostami, Amin
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p. 6600 - 6613
(2020/11/16)
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- Highly efficient oxidation of alcohols to carboxylic acids using a polyoxometalate-supported chromium(iii) catalyst and CO2
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Direct catalytic oxidation of alcohols to carboxylic acids is very attractive, but economical catalysis systems have not yet been well established. Here, we show that a pure inorganic ligand-supported chromium compound, (NH4)3[CrMo6O18(OH)6] (simplified as CrMo6), could be used to effectively promote this type of reaction in the presence of CO2. In almost all cases, oxidation of various alcohols (aromatic and aliphatic) could be achieved under mild conditions, and the corresponding carboxylic acids can be achieved in high yield. The chromium catalyst 1 can be reused several times with little loss of activity. Mechanism study and control reactions demonstrate that the acidification proceeds via the key oxidative immediate of aldehydes.
- Han, Sheng,Wang, Ying,Wei, Yongge,Wu, Zhikang,Yu, Han
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supporting information
p. 3150 - 3154
(2020/06/19)
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- Method for synthesizing phenol or derivative thereof in aqueous phase by photocatalytic one-pot method
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The invention discloses a method for synthesizing phenol or a derivative thereof in an aqueous phase by a photocatalytic one-pot method. The method comprises the following steps: by taking a compoundaryl halide shown in formula (I) as a raw material and water as a solvent, adding a catalyst and an auxiliary agent, and carrying out reacting under the conditions of alkali and visible light to obtain the phenol or the derivative (II) thereof. Compared with the prior art, the method is applicable to a large number of functional groups, high in yield, few in byproducts, simple and safe to operate,low in cost and environmentally friendly, wherein R is selected from substituted or non-substituted phenyl, pyridyl, quinolyl or pyrimidinyl; X is selected from halogen; the substituted phenyl is substituted by C1-C4 alkyl, C1-C4 alkoxy, hydroxyl, halogen, cyano, aldehyde group, nitro, amino, acetyl or carboxyl; and the substituted pyridyl, quinolyl or pyrimidinyl is pyridyl, quinolyl or pyrimidinyl substituted by C1-C4 alkyl.
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Paragraph 0032-0033; 0066-0067; 0085-0106
(2020/12/08)
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- Synthesis of salicylaldehyde through oxidation of o-cresol: Evaluation of activity and selectivity of different metals supported on OMS-2 nanorods and kinetics
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Octahedral molecular sieve (OMS-2) was synthesized by the hydrothermal method and modified by the impregnation of different metals to give M/OMS-2 catalysts (where M = V, Cr, Fe, Co, and Mo). All these catalysts were tested in the oxidation of o-cresol to 2-hydroxybenzaldehyde (or salicylaldehyde, SAL). Among all M/OMS-2 catalysts, 5% Co/OMS-2 was found to be the most active catalyst for selective oxidation of o-cresol to SAL. Effect of several oxygen sources such as air, hydrogen peroxide (H2O2), molecular oxygen (O2), and tert-butyl hydroperoxide (TBHP) was studied for the oxidation of o-cresol. There was a complete conversion of o-cresol with 98% yield of SAL at 5 atm O2 pressure and 80 °C in 2 h. Additionally, the catalysts (virgin as well as reused forms) were characterized by FESEM, EDS, HR-TEM, XRD, CO2-TPD, TPR, Raman Spectra, BET surface area analysis, XPS, and DSC-TGA. The reaction kinetic model was developed using Mars van Krevelen mechanism. The catalyst was found to be inexpensive, robust, active, and showed very good reusability of 4 cycles, which makes it an attractive choice for o-cresol oxidation to SAL. The atom economy of the oxidation process is 98.15%. Thus, this process is an example of the synthesis of a vital chemical entity, salicylaldehyde, at mild reaction condition by a novel clean and green route.
- Pisal, Devendra S.,Yadav, Ganapati D.
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- Overcoming the Deallylation Problem: Palladium(II)-Catalyzed Chemo-, Regio-, and Stereoselective Allylic Oxidation of Aryl Allyl Ether, Amine, and Amino Acids
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We report herein a Pd(II)/bis-sulfoxide-catalyzed intramolecular allylic C-H acetoxylation of aryl allyl ether, amine, and amino acids with the retention of a labile allyl moiety. Mechanistically, the reaction proceeds through a distinct double-bond isomerization from the allylic to the vinylic position followed by intramolecular carboxypalladation and the β-hydride elimination pathway. For the first time, C-H oxidation of N-allyl-protected amino acids to furnish five-membered heterocycles through 1,3-syn-addition is established with excellent diastereoselectivity.
- Begam, Hasina Mamataj,Jana, Ranjan,Manna, Kartic,Samanta, Krishanu
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p. 7443 - 7449
(2020/10/09)
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- Di-tert-butylsilylene as a protecting group for substituted salicylic acids
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The use of di-tert-butylsilyl bis(trifluoromethanesulfonate) has been used to form cyclic protecting groups for substituted salicylic acids. The reaction works well in the presence of a variety of electron-donating groups (EDG) affording the protected compounds in moderate to excellent yields (70–99%) in most cases. In addition, a handful of electron-withdrawing groups (EWG) also provided the corresponding protected silylene derivatives in good yields (77–83%). However, substrates bearing additional ortho -substitution of the carboxylic acid moiety as well as strongly deactivating groups on the aromatic ring did not undergo reaction.
- Pongdee, Gabriel J.,Bell, Kathryn G.,Prestwood, Peri R.,Pongdee, Rongson
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supporting information
(2020/10/14)
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- Potent Photochemotherapeutic Activity of Iron(III) Complexes on Visible Light-induced Ligand to Metal Charge Transfer
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Five new ternary iron(III) complexes with phenolate-based ligands of general molecular formula, [Fe(L1)B] and [Fe(L2)B], where L1 = 2-(bis(2-hydroxybenzyl)amino)acetic acid, L2 = 2-bis[3,5-di(tert-butyl)-2-hydroxybenzyl]aminoacetic acid, B = phen (1,10-phenanthroline), ip (1H-imidazo[4,5-f ][1,10]phen-anthroline) and pyip (2-(pyren-1-yl)-1H-imidazo[4,5-f ][1,10]-phenanthroline) were synthesized and probed for visible light-induced cytotoxicity in human cervical carcinoma (HeLa) cells. The complexes in generating hydroxyl radicals from molecular oxygen on visible light-induced phenolate(O)?Fe(III) or carboxylate(O)?Fe(III) charge transfer prompted apoptosis in HeLa cells with IC50 values in the range of 4.624.3 ˉM while remaining non-toxic in dark.
- Binita Chanu, S.,Musib, Dulal,Pal, Maynak,Pal, Mrityunjoy,Raza, Md Kausar,Roy, Mithun
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supporting information
p. 724 - 727
(2020/07/02)
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- Method for recovering and preparing salicylic acid from bis(2-acetoxybenzoic acid) calcium urea production waste solid
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The invention belongs to the field of waste residue treatment in chemical pharmaceutical production, and in particular, relates to a method for recycling and preparing salicylic acid from residual mixture (bis(2-acetoxybenzoic acid) calcium urea and reaction by-products) waste solid after a solvent is recycled from centrifugal mother liquor in the production process of bis(2-acetoxybenzoic acid) calcium urea. According to the method, salicylic acid is recycled and prepared from mixture waste solids generated in the production process of bis(2-acetoxybenzoic acid) calcium urea through hydrolysis, filter pressing, acid precipitation, centrifugation and drying. The method is simple to operate, easy to control and high in yield, the obtained product is high in purity, and the HPLC purity can reach 100%. Comprehensive recycling of the production waste residues is achieved, the production cost is reduced, and the recycling process is stable and suitable for industrial requirements.
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Paragraph 0012-0019
(2020/07/03)
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- Metal-free Synthesis of Spiro-2,2′-benzo[b]furan-3,3′-ones via PhI(OAc)2-Mediated Cascade Spirocyclization
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Treating the benzyl protected 3-hydroxy-1,3-bis(2-hydroxyphenyl)prop-2-en-1-ones solely with PhI(OAc)2 (PIDA) in DCE at room temperature readily furnished the seldom studied spiro-2,2′-benzo[b]furan-3,3′-ones in satisfactory to excellent yields. The hypervalent iodine reagent enables the metal-free cascade spirocyclization resulting in the dual oxidative C?O bond formation. (Figure presented.).
- Xing, Qingyu,Liang, Huiyuan,Bao, Mingmai,Li, Xuemin,Zhang, Jingran,Bi, Tianhao,Zhang, Yilin,Xu, Jun,Du, Yunfei,Zhao, Kang
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supporting information
p. 4669 - 4673
(2019/09/17)
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- 1H NMR as a quick screen for photocatalytic reaction efficiency
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1H NMR is a common technique for tracking chemical reactions; here it is demonstrated that it can be used effectively to evaluate efficiency of photocatalysts. The photocatalytic degradation of acetylsalicylic acid (Aspirin) by P25 TiO2 and its photolytic degradation by UV light were examined; and they were found to be comparable, suggesting that this breakdown reaction does not benefit greatly from the catalyst's presence. Due to its chemical specificity, 1H NMR enables identification of breakdown products, which is a useful consideration in wastewater treatment and mechanistic studies.
- Croxall, Mark P.,Lawrence, Reece T.,Goh, M. Cynthia
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- Application of quebrachitol in hydrolysis reaction of copper-catalyzed aryl halide
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The invention belongs to the technical field of drug synthesis, and provides application of quebrachitol in a hydrolysis reaction of a copper-catalyzed aryl halide. According to the hydrolysis reaction, copper serves as a catalyst, quebrachitol serves as a ligand, and the hydrolysis reaction is carried out on the aryl halide. The invention further provides a catalytic system of the hydrolysis reaction of the aryl halide. The reaction system comprises the copper catalyst, the quebrachitol, alkali and water, and the system is environmentally friendly and is suitable for industrial application.
- -
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Paragraph 0078-0080
(2019/07/16)
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- Fe3O4@SiO2@Im[Cl]Mn(III)-complex as a highly efficient magnetically recoverable nanocatalyst for selective oxidation of alcohol to imine and oxime
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An efficient and environmentally friendly oxidation process for the one-pot preparation of oxime, imine and carbonyl compounds through alcohol oxidation in the presence of H2O2 and/or O2 have been developed by a melamine-Mn(III) Schiff base complex supported on Fe3O4@SiO2–Cl nanoparticles, named as Fe3O4@SiO2@Im[Cl]Mn(III)-complex nanocomposite, at room temperature. Direct oxidation of alcohol to carboxylic acid was performed using the catalyst in the presence of molecular O2 at room temperature in a different approach. The oxidation products were obtained with excellent yields and high TOFs. The properties of the catalyst were characterized by Fourier transform infrared spectroscopy (FTIR), elemental analysis (C, H, N), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma (ICP), cyclic voltammetry (CV), nuclear magnetic resonance (1H & 13C NMR), vibration sample magnetometer (VSM), Brunauer– Emmett–Teller (BET) and differential pulse voltammetry (DPV) analyses. The mechanism of the oxidation processes was investigated for the both H2O2 and O2 oxidants. The role of the imidazolium moiety in the catalyst as a secondary functionality was investigated. Chemoselectivity behavior of the catalyst was studied by some combinations. The catalyst could be recycled from the reaction mixture by a simple external magnet and reused for several times without any considerable reactivity loss.
- Kazemnejadi, Milad,Alavi, Seyyedeh Ameneh,Rezazadeh, Zinat,Nasseri, Mohammad Ali,Allahresani, Ali,Esmaeilpour, Mohsen
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p. 230 - 249
(2019/03/28)
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- Bioinspired Trispyrazolylborato Nickel(II) Flavonolate Complexes and Their Reactivity Toward Dioxygen
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Aiming at structural and functional mimics of the active site of the NiII containing quercetin-2,4-dioxygenase NiII flavonolate complexes Tp*NiX [Tp* = hydrotris(3,5-dimethyl)pyrazolylborate, X = 3-hydroxy flavonolate (Fla), 3-hydroxy thioflavonolate (SFla), 3-hydroxy selenoflavonolate (SeFla)] were synthesized and characterized by spectroscopic methods and X-ray crystallography. The complex Tp*NiFla reacts with O2 via dioxygenation of bound flavonolate to benzoic acid and salicylic acid as one should expect for a functional model of the enzyme. Modification of the carbonyl function of the flavonolate to the corresponding C=S and C=Se compounds retained dioxygenase like reactivity, but did not lead to an increase of reaction rate as had been anticipated due to a weaker interaction of S/Se with the central nickel atom.
- Hoof, Santina,Limberg, Christian
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p. 170 - 174
(2019/01/04)
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- Identification and Directed Development of Non-Organic Catalysts with Apparent Pan-Enzymatic Mimicry into Nanozymes for Efficient Prodrug Conversion
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Nanozymes, nanoparticles that mimic the natural activity of enzymes, are intriguing academically and are important in the context of the Origin of Life. However, current nanozymes offer mimicry of a narrow range of mammalian enzymes, near-exclusively performing redox reactions. We present an unexpected discovery of non-proteinaceous enzymes based on metals, metal oxides, 1D/2D-materials, and non-metallic nanomaterials. The specific novelty of these findings lies in the identification of nanozymes with apparent mimicry of diverse mammalian enzymes, including unique pan-glycosidases. Further novelty lies in the identification of the substrate scope for the lead candidates, specifically in the context of bioconversion of glucuronides, that is, human metabolites and privileged prodrugs in the field of enzyme-prodrug therapies. Lastly, nanozymes are employed for conversion of glucuronide prodrugs into marketed anti-inflammatory and antibacterial agents, as well as “nanozyme prodrug therapy” to mediate antibacterial measures.
- Walther, Raoul,Winther, Anna K.,Fruergaard, Anne Sofie,van den Akker, Wouter,S?rensen, Lise,Nielsen, Signe Maria,Jarlstad Olesen, Morten T.,Dai, Yitao,Jeppesen, Henrik S.,Lamagni, Paolo,Savateev, Aleksandr,Pedersen, S?ren Lykke,Frich, Camilla Kaas,Vigier-Carrière, Cécile,Lock, Nina,Singh, Mandeep,Bansal, Vipul,Meyer, Rikke L.,Zelikin, Alexander N.
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supporting information
p. 278 - 282
(2018/12/05)
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- Visible light assisted photodegradation of thimerosal by high performance ZnFe2O4/poly(o-phenylenediamine) composite
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Thimerosal is a mercury-based preservative that is used in pharmaceuticals, vaccines and health-care products. However, thimerosal toxicity has been well explored and hence it should be properly treated for avoiding its occurrence in the environment. Hence, we synthesized visible light active ZnFe2O4/poly(o-phenylenediamine) composite as photocatalyst for degradation of thimerosal. The well characterized ZnFe2O4 and composite effectively degraded thimerosal and subsequently reduced Hg(II) into Hg(0) under visible light irradiation. Thimerosal degradation by-products and generation of Hg(0) were analyzed by high performance liquid chromatography and atomic fluorescence spectroscopy. The composite showed better photocatalytic activity than the pure ZnFe2O4 nanoparticles. Under the optimum conditions, 90.2% degradation of thimerosal was achieved within 6 h of irradiation. An efficient charge separation ability of poly(o-phenylenediamine) contributes to the high photocatalytic performance of the composite. This work provides a new photocatalytic degradation pathway of thimerosal and thus will stimulate further studies in the removal of organometallic contaminants.
- Sandoval, Claudio,Ranganathan, Suresh,Ramírez, Eimmy,Mansilla, Héctor D.,Dinamarca, Robinson,Pecchi, Gina,Yá?ez, Jorge
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- Integrated photocatalytic-biological treatment of triazine-containing pollutants
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The degradation of triazine-containing pollutants including simazine, Irgarol 1051 and Reactive Brilliant Red K-2G (K-2G) by photocatalytic treatment was investigated. The effects of titanium dioxide (TiO2) concentration, initial pH of reaction mixture, irradiation time and ultraviolet (UV) intensity on photocatalytic treatment efficiency were examined. Complete decolorization of K-2G was observed at 60 min photodegradation while only 15 min were required to completely degrade simazine and Irgarol 1051 under respective optimized conditions. High-performance liquid chromatography (HPLC), gas chromatography/mass spectrometry (GC/MS) and ion chromatography (IC) were employed to identify the photocatalytic degradation intermediates and products. Dealkylated intermediates of simazine, deisopropylatrazine and deethyldeisopropylatrazine, and Irgarol 1051 were detected by GC/MS in the initial phase of degradation. Complete mineralization could not be achieved for all triazine-containing pollutants even after prolonged (>72 h) UV irradiation due to the presence of a photocatalysis-resistant end product, cyanuric acid (CA). The toxicities of different compounds before and after photocatalytic treatment were also monitored by three bioassays. To further treat the photocatalysis-resistant end product, a CA-degrading bacterium was isolated from polluted marine sediment and further identified as Klebsiella pneumoniae by comparing the substrate utilization pattern (Biolog microplate), fatty acid composition and 16S rRNA gene sequencing. K. pneumoniae efficiently utilized CA from 1 to 2000 mg/L as a good nitrogen source and complete mineralization of CA was observed within 24 h of incubation. This study demonstrates that the biodegradability of triazine-containing pollutants was significantly improved by the photocatalytic pre-treatment, and this proposed photocatalytic-biological integrated system can effectively treat various classes of triazine-containing pollutants.
- Chan, Cho Yin,Chan, Ho Shing,Wong, Po Keung
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p. 371 - 380
(2019/02/07)
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- Trichloroacetonitrile as an efficient activating agent for the: Ipso -hydroxylation of arylboronic acids to phenolic compounds
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A metal-free and base-free Cl3CCN mediated method was developed for the ipso-hydroxylation of aryl boronic acids to their corresponding phenols, which was promoted by a key unstable Lewis adduct intermediate. This transformation has broad functional group tolerance, and late-stage functionalization was successful as well. After simple investigation, two pathways (radical/ionic mechanism) were suggested, and the beneficial action of blue light needs to be further studied.
- Fang, Yuanding,Zhao, Rong,Yao, Yuan,Liu, Yang,Chang, Denghu,Yao, Ming,Shi, Lei
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p. 7558 - 7563
(2019/08/20)
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- O -Hydroxycinnamate for sequential photouncaging of two different functional groups and its application in releasing cosmeceuticals
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We demonstrated a new approach for the sequential photouncaging of two different functional groups from o-hydroxycinnamate. The second caged molecule initially remains in the locked state and is released only after attaining its unlocked state upon in situ generation of the second phototrigger, i.e., coumarin, thereby leading to the sequential release of alcohol and carboxylic acid. We have utilised the above strategy for the controlled release of cosmeceutical agents.
- Paul, Amrita,Bera, Manoranjan,Gupta, Prakhar,Singh, N. D. Pradeep
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supporting information
p. 7689 - 7693
(2019/08/30)
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- The Behavior of Trispyrazolylborato-Metal(II)-Flavonolate Complexes as Functional Models for Bacterial Quercetinase-Assessment of the Metal Impact
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A series of five compounds TpMesMFla (TpMes = hydrotris(3-mesityl)pyrazolylborate; M = Mn, Fe, Co, Ni, Zn; Fla = 3-hydroxyflavonolate) has been synthesized as models for the 2,4-quercetin dioxygenase, QueD. The structures have been determined and the complexes proved to be isomorphous. Considering the structures more closely revealed that they differ in the degree of delocalization in the chelate ring formed through the binding of the two O donors of the flavonolate to the metal center, which is also supported by the results of UV-vis and IR spectroscopic investigations. The resulting trend (Zn/Fe > Co > Mn > Ni) is, however, not in line with the one that was found investigating the redox properties of the complexes by cyclic voltammetry (Zn > Fe > Ni > Co > Mn). Notably, from CV clear-cut information could be derived, as the complexes exhibited exceptionally well-behaved quasi-reversible redox transitions, indicating that the Tp ligand stabilizes the flavonolate radical formed in the oxidation process rather well. The fact that the rates, with which the complexes react with O2 in DMF solution, correlate with the position of the flavonolate redox couples, suggest that these reactions proceed via the initial electron transfer from the flavonolate to O2. After the O2 reaction, salicylic acid was identified as one of the products, the formation of which can be explained by the hydrolysis of the depside that should form upon a dioxygenation similar to the QueD enzyme-catalyzed reaction. 18O labeling experiments confirmed the presence of O2 derived O atoms. Mechanistic inferences based on the above results are discussed.
- Hoof, Santina,Limberg, Christian
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p. 12843 - 12853
(2019/10/28)
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- An Efficient Aerobic Oxidation Protocol of Aldehydes to Carboxylic Acids in Water Catalyzed by an Inorganic-Ligand-Supported Copper Catalyst
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A method for the aerobic oxidation of aldehydes to carboxylic acids in water by using an inorganic-ligand-supported copper catalyst was developed. This method was performed with the use of atmospheric oxygen as the sole oxidant under extremely mild aqueous conditions, and furthermore, a wide range of aldehydes with various functional groups were tolerated. The copper catalyst could be recycled and used in successive reactions at least six times without any appreciable degradation in performance. This method is operationally simple and avoids the use of high-costing, toxic, air/moisture-sensitive, and commercially unavailable organic ligands. The generality of this method gives it potential to be used on the industrial scale.
- Yu, Han,Ru, Shi,Zhai, Yongyan,Dai, Guoyong,Han, Sheng,Wei, Yongge
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p. 1253 - 1257
(2018/02/16)
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- A biocatalytic method for the chemoselective aerobic oxidation of aldehydes to carboxylic acids
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Herein, we present a study on the oxidation of aldehydes to carboxylic acids using three recombinant aldehyde dehydrogenases (ALDHs). The ALDHs were used in purified form with a nicotinamide oxidase (NOx), which recycles the catalytic NAD+ at the expense of dioxygen (air at atmospheric pressure). The reaction was studied also with lyophilised whole cell as well as resting cell biocatalysts for more convenient practical application. The optimised biocatalytic oxidation runs in phosphate buffer at pH 8.5 and at 40 °C. From a set of sixty-one aliphatic, aryl-Aliphatic, benzylic, hetero-Aromatic and bicyclic aldehydes, fifty were converted with elevated yield (up to >99%). The exceptions were a few ortho-substituted benzaldehydes, bicyclic heteroaromatic aldehydes and 2-phenylpropanal. In all cases, the expected carboxylic acid was shown to be the only product (>99% chemoselectivity). Other oxidisable functionalities within the same molecule (e.g. hydroxyl, alkene, and heteroaromatic nitrogen or sulphur atoms) remained untouched. The reaction was scaled for the oxidation of 5-(hydroxymethyl)furfural (2 g), a bio-based starting material, to afford 5-(hydroxymethyl)furoic acid in 61% isolated yield. The new biocatalytic method avoids the use of toxic or unsafe oxidants, strong acids or bases, or undesired solvents. It shows applicability across a wide range of substrates, and retains perfect chemoselectivity. Alternative oxidisable groups were not converted, and other classical side-reactions (e.g. halogenation of unsaturated functionalities, Dakin-Type oxidation) did not occur. In comparison to other established enzymatic methods such as the use of oxidases (where the concomitant oxidation of alcohols and aldehydes is common), ALDHs offer greatly improved selectivity.
- Knaus, Tanja,Tseliou, Vasilis,Humphreys, Luke D.,Scrutton, Nigel S.,Mutti, Francesco G.
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supporting information
p. 3931 - 3943
(2018/09/11)
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- Chemoselective ester/ether C–O cleavage of methyl anisates by aluminum triiodide
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The aluminum triiodide mediated chemoselective ester/ether C–O cleavage of methyl anisates was investigated. o-Anisate undergoes ether cleavage at low temperatures in carbon disulfide, cyclohexane and acetonitrile. Further cleavage of the ester group occurs at elevated temperatures to afford salicylic acid. The cleavage of p-anisate is solvent-dependent. In cyclohexane, the ester and ether groups were cleaved non-selectively to give equimolar amounts of p-anisic acid and methyl p-hydroxybenzoate. The ester group was preferentially cleaved in acetonitrile, compared to ether group cleavage in carbon disulfide. The ester cleavage reaction was improved using pyridine as an acid scavenger additive. Reasons for the contrasting reactivity of anisates towards AlI3 were explored, and the methods were applied to cleavage of the tert-butyl ester of acemetacin which gave different products under these conditions.
- Sang, Dayong,Yi, Cuicui,He, Zhoujun,Wang, Jiahui,Tian, Juan,Yao, Ming,Shi, Hong
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supporting information
p. 1469 - 1472
(2018/03/13)
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- First electrospun immobilized molybdenum complex on bio iron oxide nanofiber for green oxidation of alcohols
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Bio iron oxide was synthesized from natural Sesbania sesban plant and modified by a molybdenum complex (Fe2O3/MoSB). Fe2O3/MoSB was deposited on polyvinyl alcohol (PVA) using a conventional single nozzle electrospinning technique (PVA/Fe2O3/MoSB). TEM, SEM, AFM, FT-IR, TGA, EDAX, and elemental analysis were used to determine fiber compositional information. The catalytic efficiency of electrospun PVA/Fe2O3/MoSB nanofiber in the oxidation of alcohols was exploited. The green reactions were conducted at solvent free conditions as a green media in the presence of H2O2 to have the desired aldehydes and tert-butyl hydrogen peroxide to obtain acid products in high yields and excellent selectivity. The survival of this nanocomposite was investigated and it could be reused and recycled in consecutive runs.
- Noghi, Sedighe Abbaspour,Naeimi, Atena,Hamidian, Hooshang
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p. 229 - 237
(2018/07/13)
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- Pd-Catalyzed debenzylation and deallylation of ethers and esters with sodium hydride
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Herein we demonstrate simply that the addition of Pd(OAc)2 as a promotor switches the reactivity of a commonly used base NaH to a nucleophilic reductant. The reactivity is engineered into a palladium-catalyzed reductive debenzylation and deallylation of aryl ethers and esters. This operationally simple, mild protocol displays a broad substrate scope and a broad spectrum of functional group tolerance (>50 examples) and high chemoselectivity toward aryl ethers over aliphatic structures. Moreover, the dual reactivity of NaH as a base and a reductant is demonstrated in efficient synthetic elaboration.
- Mao, Yujian,Liu, Ye,Hu, Yanwei,Wang, Liang,Zhang, Shilei,Wang, Wei
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p. 3016 - 3020
(2018/04/14)
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- Convenient and Rapid Synthesis of 3-Selenocyanato-4 H -chromen-4-ones
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A sequential one-pot, simple and convenient method is described for the synthesis of 3-selenocyanato-4 H -chromen-4-ones by addition, first of DMF-DMA and then of triselenodicyanide as electrophile.
- Kosso, Anne Roly Obah,Broggi, Julie,Redon, Sébastien,Vanelle, Patrice
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p. 1215 - 1218
(2018/03/26)
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- Synthesis and spectroscopic/DFT structural characterization of coordination compounds of Nb(V) and Ti(IV) with bioactive carboxylic acids
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The reactions are reported of NbX5 (X = Cl, Br), TiCl4 and Ti(OiPr)4 with a selection of carboxylic acids exhibiting a known biological role, in a chlorinated solvent. The reactions of NbX5 with acetylsalicylic acid (aspirin) proceeded with selective deacetylation of the organic reactant and formation of the salicylate complexes NbX4(C7H5O3) (1a, X = Cl; 1b, X = Br) in 60–65% yields. NbCl5 reacted with diclofenac and ethacrynic acid (EA-CO2H) to give NbCl3[κ3O,O,N-O2CCH2(C6H4)NC6H3Cl2], 2 (80% yield), and NbCl4(O2C-EA), 3 (72% yield), respectively. Ti(OiPr)4 reacted with ethacrynic acid giving Ti(OiPr)2(O2C-EA)2, 4, in 74% yield, as a mixture of two isomers. All the products were characterized by means of analytical and spectroscopic methods, moreover DFT studies were carried out to give insight into structural features.
- De Palo, Alice,Biancalana, Lorenzo,Bortoluzzi, Marco,Alessandra Martini, Maria,Marchetti, Fabio,Pampaloni, Guido
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p. 208 - 214
(2017/12/26)
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- Ultrasensitive Fluorescence Detection of Peroxymonosulfate Based on a Sulfate Radical-Mediated Aromatic Hydroxylation
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Recently, peroxymonosulfate (PMS)-based advanced oxidation processes have exhibited broad application prospects in the environment field. Accordingly, a simple, rapid, and ultrasensitive method is highly desired for the specific recognition and accurate quantification of PMS in various aqueous solutions. In this work, SO4?--induced aromatic hydroxylation was explored, and based on that, for the first time, a novel fluorescence method was developed for the PMS determination using Co2+ as a PMS activator and benzoic acid (BA) as a chemical probe. Through a suite of spectral, chromatographic, and mass spectrometric analyses, SO4?- was proven to be the dominant radical species, and salicylic acid was identified as the fluorescent molecule. As a result, a whole radical chain reaction mechanism for the generation of salicylic acid in the BA/PMS/Co2+ system was proposed. This fluorescence method possessed a rapid reaction equilibrium (a wide detection range (0-100 μM). Moreover, it performed well in the presence of possible interfering substances, including two other peroxides (i.e., peroxydisulfate and hydrogen peroxide), some common ions, and organics. The detection results for real water samples further validated the practical utility of the developed fluorescence method. This work provides a new method for the specific recognition and sensitive determination of PMS in complex aqueous solutions.
- Huang, Gui-Xiang,Si, Jin-Yan,Qian, Chen,Wang, Wei-Kang,Mei, Shu-Chuan,Wang, Chu-Ya,Yu, Han-Qing
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p. 14439 - 14446
(2019/01/03)
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- Copper(II)-Mediated ortho-Selective C(sp2)-H Tandem Alkynylation/Annulation and ortho-Hydroxylation of Anilides with 2-Aminophenyl-1H-pyrazole as a Directing Group
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2-Aminophenyl-1H-pyrazole has been identified as a viable directing group to promote copper(II)-mediated ortho-selective sp2 C-H bond tandem alkynylation/annulation of anilides with terminal alkynes to offer arylmethylene isoindolinones. Meanwhile, copper(II)-mediated ortho-selective sp2 C-H hydroxylation of anilides has also been optimized as the major reaction pathway by using Cu(OAc)2 as the promoter and 1,1,3,3-tetramethylguanidine as an organic base. Recovery of the directing group was achieved by hydrazinolysis for arylmethylene isoindolinones and basic hydrolysis for the hydroxylation products.
- Lee, Wan-Chen Cindy,Wang, Wei,Li, Jie Jack
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p. 2382 - 2388
(2018/02/23)
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- Direct C(sp2)?H Hydroxylation of Arenes with Palladium(II)/Oxygen Using Sulfoximines as a Recyclable Directing Group
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The aerobic palladium(II) catalysis presented herein offers facile entry to various substituted phenols through site-selective C?H hydroxylation of arenes by using sulfoximines as a reusable directing group. The notable aspects of our method include the use of molecular oxygen (O2) as the sole oxidant, the activation of molecular oxygen through aldehyde autoxidation, operational simplicity, and the mechanistic studies into the catalytic C?H hydroxylation process.
- Das, Prasenjit,Guin, Joyram
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p. 2370 - 2373
(2018/04/25)
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