- Imidazolium-urea low transition temperature mixtures for the UHP-promoted oxidation of boron compounds
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Different carboxy-functionalized imidazolium salts have been considered as components of low transition temperature mixtures (LTTMs) in combination with urea. Among them, a novel LTTM based on 1-(methoxycarbonyl)methyl-3-methylimidazolium chloride and urea has been prepared and characterized by differential scanning calorimetry throughout its entire composition range. This LTTM has been employed for the oxidation of boron reagents using urea-hydrogen peroxide adduct (UHP) as the oxidizer, thus avoiding the use of aqueous H2O2, which is dangerous to handle. This metal-free protocol affords the corresponding alcohols in good to quantitative yields in up to 5 mmol scale without the need of further purification. The broad composition range of the LTTM allows for the reaction to be carried out up to three consecutive times with a single imidazolium salt loading offering remarkable sustainability with an E-factor of 7.9, which can be reduced to 3.2 by the threefold reuse of the system.
- Martos, Mario,Pastor, Isidro M.
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- Electrophotocatalytic C?H Heterofunctionalization of Arenes
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The electrophotocatalytic heterofunctionalization of arenes is described. Using 2,3-dichloro-5,6-dicyanoquinone (DDQ) under a mild electrochemical potential with visible-light irradiation, arenes undergo oxidant-free hydroxylation, alkoxylation, and amination with high chemoselectivity. In addition to batch reactions, an electrophotocatalytic recirculating flow process is demonstrated, enabling the conversion of benzene to phenol on a gram scale.
- Huang, He,Lambert, Tristan H.
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supporting information
p. 11163 - 11167
(2021/04/19)
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- Aromatic C?H Hydroxylation Reactions with Hydrogen Peroxide Catalyzed by Bulky Manganese Complexes
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The oxidation of aromatic substrates to phenols with H2O2 as a benign oxidant remains an ongoing challenge in synthetic chemistry. Herein, we successfully achieved to catalyze aromatic C?H bond oxidations using a series of biologically inspired manganese catalysts in fluorinated alcohol solvents. While introduction of bulky substituents into the ligand structure of the catalyst favors aromatic C?H oxidations in alkylbenzenes, oxidation occurs at the benzylic position with ligands bearing electron-rich substituents. Therefore, the nature of the ligand is key in controlling the chemoselectivity of these Mn-catalyzed C?H oxidations. We show that introduction of bulky groups into the ligand prevents catalyst inhibition through phenolate-binding, consequently providing higher catalytic turnover numbers for phenol formation. Furthermore, employing halogenated carboxylic acids in the presence of bulky catalysts provides enhanced catalytic activities, which can be attributed to their low pKa values that reduces catalyst inhibition by phenolate protonation as well as to their electron-withdrawing character that makes the manganese oxo species a more electrophilic oxidant. Moreover, to the best of our knowledge, the new system can accomplish the oxidation of alkylbenzenes with the highest yields so far reported for homogeneous arene hydroxylation catalysts. Overall our data provide a proof-of-concept of how Mn(II)/H2O2/RCO2H oxidation systems are easily tunable by means of the solvent, carboxylic acid additive, and steric demand of the ligand. The chemo- and site-selectivity patterns of the current system, a negligible KIE, the observation of an NIH-shift, and the effectiveness of using tBuOOH as oxidant overall suggest that hydroxylation of aromatic C?H bonds proceeds through a metal-based mechanism, with no significant involvement of hydroxyl radicals, and via an arene oxide intermediate. (Figure presented.).
- Masferrer-Rius, Eduard,Borrell, Margarida,Lutz, Martin,Costas, Miquel,Klein Gebbink, Robertus J. M.
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p. 3783 - 3795
(2021/03/09)
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- Catalytic Enantioselective Synthesis of Axially Chiral Diarylmethylidene Indanones
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We describe the first atropselective Suzuki-Miyaura cross-coupling of β-keto enol triflates to access axially chiral (Z)-diarylmethylidene indanones (DAIs). The chemical, physical, and biological properties of DAIs are unknown, despite their being structurally similar to arylidene indanones, primarily due to the lack of racemic or chiral methods. Through this work, we demonstrate a general and efficient protocol for the racemic as well as the atropselective synthesis of (Z)-DAIs. An unusual intramolecular Morita-Baylis-Hillman reaction is utilized for the Z-selective synthesis of β-keto enol triflates.
- Kumar, Prashant,Shirke, Rajendra P.,Yadav, Sonu,Ramasastry
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supporting information
p. 4909 - 4914
(2021/06/30)
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- Selective Bromination of β-Positions of Porphyrin by Self-Catalytic Behaviour of VOTPP: Facile Synthesis, Electrochemical Redox Properties and Catalytic Application
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Oxidovanadium(IV) complex of β-octabromo-meso-tetraphenylporphyrin, {[VIVO(TPPBr8)], 2} was synthesized by self-catalytic oxidative bromination of meso-tetraphenylporphyrinatooxidovanadium(IV) {[VIVO(TPP), 1} in excellent yield under mild conditions at 25 °C and its structure was confirmed by single crystal X-ray study. UV-Vis and 1H NMR spectra further confirmed that the meso-phenyl rings are not brominated and thus emphasizes on the selectivity as well as synthetic importance of this catalytic method. In the presence of substrates e. g. phenol derivatives, 1 biomimics the vanadium bromoperoxidase (VBPO) enzyme and catalyses the oxidative bromination of substrates in water at 25 °C. Remarkably, 2 also catalyses the oxidative bromination of phenol derivatives under similar reaction conditions with very high turnover frequency (TOF) values (ca. 29 s?1) along with its recyclability. It was found that 2 showed superior catalytic performance as compared to 1 because of its electron deficient nature due to electron withdrawing bromo substituents and robust saddle shaped nonplanar structure (further supported by DFT studies).
- Maurya, Mannar R.,Prakash, Ved,Avecilla, Fernando,Sankar, Muniappan
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supporting information
p. 1685 - 1694
(2021/05/03)
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- Ni-NiO heterojunctions: a versatile nanocatalyst for regioselective halogenation and oxidative esterification of aromatics
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Herein, we report a facile method for the synthesis of Ni-NiO heterojunction nanoparticles, which we utilized for the nuclear halogenation reaction of phenol and substituted phenols usingN-bromosuccinimide (NBS). A remarkablepara-selectivity was achieved for the halogenated products under semi-aqueous conditions. Interestingly, blocking of thepara-position of phenol offeredortho-selective halogenation. In addition, the Ni-NiO nanoparticles catalyzed the oxidative esterification of carbonyl compounds with alcohol, diol or dithiol in the presence of a catalytic amount of NBS. It was observed that the aromatic carbonyls substituted with an electron-donating group favoured nuclear halogenation, whereas an electron-withdrawing group substitution in carbonyl compounds facilitated the oxidation reaction. In addition, the catalyst was magnetically separated and recycled 10 times. The tuned electronic structure at the Ni-NiO heterojunction controlled selectivity and activity as no suchpara-selectivity was observed with commercially available NiO or Ni nanoparticles.
- Bhardwaj, Nivedita,Goel, Bharat,Indra, Arindam,Jain, Shreyans K.,Singh, Ajit Kumar,Tripathi, Nancy
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supporting information
p. 14177 - 14183
(2021/08/16)
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- Halogenated method of aromatic compound
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The invention belongs to the field of organic synthesis, and particularly relates to synthesis of aromatic halogens, in particular to arylamine. The invention discloses a synthesis method of a corresponding ortho-halogenated product from aromatic compounds such as carbazole and phenol. The method comprises the following steps: adding a metal sulfonate salt catalyst, aromatic amine, carbazole, phenol and other hydrogen - heteroatom-containing aromatic compound reaction substrates, a halogenation reagent and a reaction solvent at a specific reaction temperature. After the drying agent is dried, the yield of the reaction product and the nuclear magnetic characterization determining structure are determined by column chromatography. The reaction product yield is determined by gas chromatography. By adopting the method, under the cheap metal salt catalyst, a plurality of ortho-substituted brominated and chloro products can be obtained with moderate to excellent yield.
- -
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Paragraph 0199-0201; 0233-0238
(2021/11/10)
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- Highly efficient, recyclable and alternative method of synthesizing phenols from phenylboronic acids using non-endangered metal: Samarium oxide
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Oxidation of phenylboronic acid to phenol is one of the important industrial processes and it is generally employed in the plastic, explosive and drug manufacturing industries. Over the past decades, numerous efficient methods have been described for the generation of phenols from phenylboronic acids in the presence of oxidant. However, these methods suffered from various limitations, including the use of expensive, toxic reagents and sophisticated protocol to synthesise the phenols. Additionally, some of these reported literatures employed endangered metals, in which mankind is facing the risk of limited supply of these elements in 20 years’ time from now. As such, a viable alternative and green method for achieving organic synthesis is highly sought after by the chemists of today. Herein, we report for the first time a facile, efficient and alternative method in the preparation of phenols from phenylboronic acids using non-endangered metal as catalyst. In all cases, all phenols were afforded in satisfactory yields (81–96%) by employing column-free method. In the recyclability study, the Sm2O3 catalyst was found to possess good catalytic performance, even after being reused for five consecutive times (96–91%). In addition, SEM result revealed that the morphology of the recycled Sm2O3 catalyst was well preserved after five successive uses, which indicate no observable changes occurred in the recovered catalysts. As a final note, the current method is anticipated to be useful for industries manufacturing chemical intermediates as it provides an alternative method of catalysis by using a non-endangered metal in organic transformations.
- Yusoff, Hanis Mohd,Bala Chandran, Prasana Devi,Sayuti, Fatin Amira Binti,Kan, Su-Yin,Mohd Radzi, Siti Aisha,Yong, Fu-Siong Julius,Lee, Oon Jew,Chia, Poh Wai
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- Cu2O/TiO2 as a sustainable and recyclable photocatalyst for gram-scale synthesis of phenols in water
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A green and straightforward protocol was developed for the synthesis of phenols from aryl boronic acid using an inexpensive and available Cu2O/TiO2 photocatalyst under visible light and sunlight. This approach proceeded in mild reaction conditions in water and the presence of air as a green oxidant, resulting in the corresponding phenols in good to excellent yields. Sunlight was also a sustainable source for this photochemical reaction. Heterogeneous nano photocatalyst was successfully recovered in 8 consecutive runs. It is noteworthy that, the photocatalyst exhibited high activity for the large-scale synthesis of phenols.
- Hosseini-Sarvari, Mona,Keshavarz, Kimia,Tavakolian, Mina
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- The graphite-catalyzed: ipso -functionalization of arylboronic acids in an aqueous medium: metal-free access to phenols, anilines, nitroarenes, and haloarenes
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An efficient, metal-free, and sustainable strategy has been described for the ipso-functionalization of phenylboronic acids using air as an oxidant in an aqueous medium. A range of carbon materials has been tested as carbocatalysts. To our surprise, graphite was found to be the best catalyst in terms of the turnover frequency. A broad range of valuable substituted aromatic compounds, i.e., phenols, anilines, nitroarenes, and haloarenes, has been prepared via the functionalization of the C-B bond into C-N, C-O, and many other C-X bonds. The vital role of the aromatic π-conjugation system of graphite in this protocol has been established and was observed via numerous analytic techniques. The heterogeneous nature of graphite facilitates the high recyclability of the carbocatalyst. This effective and easy system provides a multipurpose approach for the production of valuable substituted aromatic compounds without using any metals, ligands, bases, or harsh oxidants.
- Badgoti, Ranveer Singh,Dandia, Anshu,Parewa, Vijay,Rathore, Kuldeep S.,Saini, Pratibha,Sharma, Ruchi
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p. 18040 - 18049
(2021/05/29)
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- Method for hydroxylating aromatic compound
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The invention provides a method for directly hydroxylating an aromatic compound. The method comprises the following steps: dissolving the aromatic compound in a solvent, adding hydrogen peroxide and anitroxide free radical compound, and reacting. The nitroxide free radical compound is used as a catalyst, hydrogen peroxide is used as an oxidizing agent, and hydroxylation of the aromatic compound is directly catalyzed and oxidized. Compared with a traditional process, the method has the advantages of high product selectivity, mild reaction conditions, reusability of the catalyst, easiness in separation of oxidation products and raw materials and the like.
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-
Paragraph 0104-0105
(2020/06/17)
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- Triptycenyl Sulfide: A Practical and Active Catalyst for Electrophilic Aromatic Halogenation Using N-Halosuccinimides
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A Lewis base catalyst Trip-SMe (Trip = triptycenyl) for electrophilic aromatic halogenation using N-halosuccinimides (NXS) is introduced. In the presence of an appropriate activator (as a noncoordinating-anion source), a series of unactivated aromatic compounds were halogenated at ambient temperature using NXS. This catalytic system was applicable to transformations that are currently unachievable except for the use of Br2 or Cl2: e.g., multihalogenation of naphthalene, regioselective bromination of BINOL, etc. Controlled experiments revealed that the triptycenyl substituent exerts a crucial role for the catalytic activity, and kinetic experiments implied the occurrence of a sulfonium salt [Trip-S(Me)Br][SbF6] as an active species. Compared to simple dialkyl sulfides, Trip-SMe exhibited a significant charge-separated ion pair character within the halonium complex whose structural information was obtained by the single-crystal X-ray analysis. A preliminary computational study disclosed that the πsystem of the triptycenyl functionality is a key motif to consolidate the enhancement of electrophilicity.
- Nishii, Yuji,Ikeda, Mitsuhiro,Hayashi, Yoshihiro,Kawauchi, Susumu,Miura, Masahiro
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supporting information
p. 1621 - 1629
(2020/02/04)
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- “Hetero-Multifunctionalization” of Gallium Corroles: Facile Synthesis, Phosphorescence, Redox Tuning, and Photooxidative Catalytic Improvement
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Bromination of tris- and tetrakis-trifluoromethylated gallium corroles (3CF3?Ga and 4CF3?Ga) afforded tetrabrominated species 3CF3?4Br?Ga and 4CF3?4Br?Ga (yields: 20 % and 25 %) characterized by NMR, UV-vis spectroscopy, and mass spectrometry. Red-shifted absorption and emission bands were found; 3CF3?4Br?Ga and 4CF3?4Br?Ga displayed 5–12 nm shifts in their Soret bands and 8–17 nm shifts for their Q bands, compared to the respective nonbrominated species (3CF3?Ga and 4CF3?Ga). The respective ΦF values were found to be 0.013 and 0.016; phosphorescence (lifetime=0.23 μs) was observed for 3CF3?4Br?Ga (anaerobic, RT). The effect of tetrabromination on redox potentials (0.89 and 0.99 V) gave a 85 mV shift per Br atom in the reduction potential. 4CF3?4Br?Ga allows for efficient catalytic photooxidative Br? to Br2 conversion compared to the β-octa-Br system (Br8?Ga) structurally characterized here. This “hetero-multifunctionalization” approach, that is, is substitution with different sets of β-substituents, can help optimize porphyrinoid properties.
- Zhan, Xuan,Zini, Yael,Fridman, Natalia,Chen, Qiu-Cheng,Churchill, David G.,Gross, Zeev
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p. 163 - 168
(2019/12/24)
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- Activity and specificity studies of the new thermostable esterase EstDZ2
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In this paper, we study the activity and specificity of EstDZ2, a new thermostable carboxyl esterase of unknown function, which was isolated from a metagenome library from a Russian hot spring. The biocatalytic reaction employing EstDZ2 proved to be an efficient method for the hydrolysis of aryl p-, o- or m-substituted esters of butyric acid and esters of secondary alcohols. Docking studies revealed structural features of the enzyme that led to activity differences among the different substrates.
- Myrtollari, Kamela,Katsoulakis, Nikolaos,Zarafeta, Dimitra,Pavlidis, Ioannis V.,Skretas, Georgios,Smonou, Ioulia
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supporting information
(2020/09/16)
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- Nickel-catalyzed removal of alkene protecting group of phenols, alcohols via chain walking process
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An efficient nickel-catalyzed removal of alkene protection group under mild condition with high functional group tolerance through chain walking process has been established. Not only phenolic ethers, but also alcoholic ethers can be tolerated with the retention of stereocenter adjacent to hydroxyl group. The new reaction brings the homoallyl group into a start of new type of protecting group.
- Meng, Chenkai,Niu, Haolin,Ning, Juehan,Wu, Wengang,Yi, Jun
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- A scalable and green one-minute synthesis of substituted phenols
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A mild, green and highly efficient protocol was developed for the synthesis of substituted phenols via ipso-hydroxylation of arylboronic acids in ethanol. The method utilizes the combination of aqueous hydrogen peroxide as the oxidant and H2O2/HBr as the reagent under unprecedentedly simple and convenient conditions. A wide range of arylboronic acids were smoothly transformed into substituted phenols in very good to excellent yields without chromatographic purification. The reaction is scalable up to at least 5 grams at room temperature with one-minute reaction time and can be combined in a one-pot sequence with bromination and Pd-catalyzed cross-coupling to generate more diverse, highly substituted phenols.
- Elumalai, Vijayaragavan,Hansen, J?rn H.
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p. 40582 - 40587
(2020/11/18)
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- Trifluoromethyl aryl sulfonates (TFMS): An applicable trifluoromethoxylation reagent
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Fluorine is probably another favorite hetero-atom for incorporation into small molecules after nitrogen. Among many fluorine-containing groups, trifluoromethyl aryl ethers (ArOCF3) have unique properties in drug design and are difficult to be synthesized, and many different methods were developed to prepare them. A novel one-pot synthesis of o-iodine-aryl trifluoromethyl ethers (ArOCF3I) was described by the reaction of trifluoromethoxylation and iodination with trifluoromethyl aryl sulfonates (TFMS) in this manuscript. The reaction conditions were optimized by screening different solvents, crown ethers, substrates and the ratios and the yields of products were in moderate to high yields (up to 86%).
- Lei, Meng,Miao, Hang,Wang, Xueyuan,Zhang, Wen,Zhu, Chengjian,Lu, Xiaqiang,Shen, Jian,Qin, Yanru,Zhang, Haoyang,Sha, Sijia,Zhu, Yongqiang
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supporting information
p. 1389 - 1392
(2019/04/30)
-
- Construction of Phenanthrenes and Chrysenes from β-Bromovinylarenes via Aryne Diels-Alder Reaction/Aromatization
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A highly efficient transition-metal-free general method for the synthesis of polycyclic aromatic hydrocarbons like phenanthrenes and chrysenes (and tetraphene) from β-bromovinylarenes and arynes has been developed. The reactions proceed via an aryne Diels-Alder (ADA) reaction, followed by a facile aromatization. This is the first report on direct construction of chrysenes (and tetraphene) using the ADA approach. Unlike the literature method which is limited to only 9/10-substituted derivatives, this method gives access to a wide variety of functionalized phenanthrenes.
- Singh, Vikram,Verma, Ram Subhawan,Khatana, Anil K.,Tiwari, Bhoopendra
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supporting information
p. 14161 - 14167
(2019/10/28)
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- Robust and electron deficient oxidovanadium(iv) porphyrin catalysts for selective epoxidation and oxidative bromination reactions in aqueous media
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meso-Tetrakis(3,5-dimethoxyphenyl)porphyrinatooxidovanadium (1) and β-octabromo-meso-tetrakis(2,6-dibromo-3,5-dimethoxyphenyl)porphyrinatooxidovanadium (2) were synthesized in excellent yields. The synthesized oxidovanadium(iv) porphyrin complexes were characterized by various spectroscopic methods such as UV-Vis, FT-IR, EPR and MALDI-TOF mass spectrometry, as well as by single crystal X-ray crystallography. The acetonitrile coordinated porphyrin 1 is relatively planar whereas 2 is highly nonplanar as shown by their crystal structures and also by electrochemical studies. Selective epoxidation studies of alkenes were successfully carried out in CH3CN/H2O as the solvent mixture at ambient temperature resulting in very high TOF numbers (12227-14347 h-1 for 2) even with low catalyst loadings. Remarkably, 2 biomimics the vanadium bromoperoxidase (VBrPO) enzyme with extremely high TOF values (83333-87719 h-1) for the oxidative bromination of thymol and some other phenols. Both the catalysts were successfully recovered at the end of the reactions, indicating their viability and industrial applicability.
- Dar, Tawseef Ahmad,Uprety, Bhawna,Sankar, Muniappan,Maurya, Mannar R.
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p. 1757 - 1768
(2019/04/08)
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- Maximizing Property Tuning of Phosphorus Corrole Photocatalysts through a Trifluoromethylation Approach
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An eight-member series of CF3-substituted difluorophosphorus corroles was prepared for establishing a structure-activity profile of these high-potential photosensitizers. It consisted of preparing all four possible isomers of the monosubstituted corrole and complexes with 2-, 3-, 4-, and 5-CF3 groups on the macrocycle's periphery. The synthetic pathway to these CF3-substituted derivatives, beginning with (tpfc)PF2, involves two different initial routes: (i) direct electrophilic CF3 incorporation using FSO2CF2CO2Me and copper iodide, or (ii) bromination to achieve the 2,3,8,17,18-pentabrominated compound using excess bromine in methanol. Crystallographic investigations revealed that distortion of the original planar macrocycle is evident even in the monosubstituted case and that it becomes truly severe for the penta-CF3-substituted derivative 5. There is a shift in redox potentials of about 193 mV per -CF3 group, which decreases to only 120 mV for the fifth one in 5. Differences in the electronic spectra suggest that the Gouterman four orbital model decreases in relevance upon gradual -CF3 substitution, a conclusion that was corroborated by DFT calculations. The very significant energy lowering of the frontier orbitals suggested that photoexcitation should lead to a highly oxidizing photocatalyst. This hypothesis was proven true by finding that the most synthetically accessible CF3-substituted derivative is an excellent catalyst for the photoinduced conversion of bromide to bromine (phenol, toluene, and benzene assay).
- Zhan, Xuan,Teplitzky, Peter,Diskin-Posner, Yael,Sundararajan, Mahesh,Ullah, Zakir,Chen, Qiu-Cheng,Shimon, Linda J. W.,Saltsman, Irena,Mahammed, Atif,Kosa, Monica,Baik, Mu-Hyun,Churchill, David G.,Gross, Zeev
-
supporting information
p. 6184 - 6198
(2019/05/08)
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- Synthesis of Ti-Al binary oxides and their catalytic application for C-H halogenation of phenols, aldehydes and ketones
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Traditional C–H halogenation of organic compounds often requires corrosive agent or harsh condition, and current researches are focused on the use of noble metals as catalyst. In order to give an efficient, benign, activity-adjustable and cost-effective system for halogenation, a series of Ti-Al mixed oxides are prepared as catalyst through sol-gel in this work. Characterizations reveal all catalysts contain more aluminum than titanium, but preparative conditions affect their composition and crystallinity. Monitoring of particle size, zeta potential and UV–vis of preparative solution reveals that formation of catalyst colloids undergoes chemical reaction, affecting catalyst morphology. In halogenation, all catalysts show moderate to high activities, copper chloride proves to be an effective halogen source rather than sodium chloride. The chlorination and bromination are better than iodization, phenol and ketone appear to be more appropriate substrates than aldehyde. Additionally, oxide backbone of catalyst is more durable than its organic components during recycling. This study may provide new catalytic materials for progress of C–H activation.
- Su, Peigen,Fan, Chao,Yu, Heng,Wang, Wanqin,Jia, Xin,Rao, Qifan,Fu, Chenxi,Zhang, Donghua,Huang, Benhua,Pan, Cheng,Zheng, Aqun,Sun, Yang
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- Mild and Regioselective Bromination of Phenols with TMSBr
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In this work, an unexpected promoting effect of by-product thioether was observed, leading to a mild and regioselective bromination of phenols with TMSBr. This method can tolerate a series of functional groups such as the reactive methoxyl, amide, fluoro, chloro, bromo, aldehyde, ketone and ester groups, and has the potential to recycle the by-product thioether and isolate the desired product under column chromatography-free conditions. Mechanism studies revealed that O–H···S hydrogen bond may be formed between phenol and by-product thioether. Possibly owing to the steric hindrance effect from by-product thioether, the electrophilic bromination at para-position of phenols is much favorable.
- Ma, Xiantao,Yu, Jing,Jiang, Mengyuan,Wang, Mengyu,Tang, Lin,Wei, Mengmeng,Zhou, Qiuju
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supporting information
p. 4593 - 4596
(2019/07/05)
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- Positive shift in corrole redox potentials leveraged by modest β-CF3-substitution helps achieve efficient photocatalytic C-H bond functionalization by group 13 complexes
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Tris- A nd tetrakis-β-trifluoromethylated gallium (3CF3-Ga, 4CF3-Ga) and aluminum (3CF3-Al, 4CF3-Al) corrole systems were synthesized by a facile "one-pot" approach from the respective tri- A nd tetra-iodo starting compounds using the FSO2CF2CO2Me reagent. The isolated 5,10,15-(tris-pentafluorophenyl)corrole-based compounds set the groundwork for another important β-substituent study in inorganic photocatalysis. As seen previously,-CF3 group substitution leads to red shifts in both the absorption and emission spectra compared to their unsubstituted counterparts (X. Zhan, et al., Inorg. Chem., 2019, 58, 6184-6198). All CF3-substituted corrole complexes showed strong fluorescence; 3CF3-Al possessed the highest fluorescence quantum yield (0.71) among these compounds. The photocatalytic production of bromophenol by way of these photosensitizing complexes was studied demonstrating that tris-trifluoromethylation is an important substitution class, especially when Ga3+ is present (experimental TON value in parentheses): 3CF3-Ga (192) > 4CF3-Ga (146) > 3CF3-Al (130) > 4CF3-Al (56) > 1-Ga (43) > 1-Al (18). The catalytic performance (turn-over number, TON) for benzylbromide formation (from toluene) was found to be: 3CF3-Ga (225) > 1-Ga (138) > 3CF3-Al (130) > 4CF3-Ga (126) > 1-Al (95) > 4CF3-Al (89); in these trials, benzaldehyde was also detected as a product in which 3CF3-Ga outperforms the other compounds (TON = 109). The tetra-CF3-substituted 4CF3-Ga and 4CF3-Al species exhibit a dramatic formal positive shift of 116 mV and 126 mV per [CF3] group, respectively, compared to the unsubstituted parent species 1-Ga and 1-Al. However, the absorbance values (λabs = 400 nm) of these corrole complexes (all equally concentrated: 4.0 × 10-6 M) were 3CF3-Al (0.23) > 3CF3-Ga (0.22) > 1-Al (0.21) > 1-Ga (0.20) > 4CF3-Al (0.19) > 4CF3-Ga (0.15), which helps rationalize why 3CF3-Ga performs the best among these catalysts. These new photosensitizers were carefully characterized by 1H and 19F NMR spectroscopy to help verify the number and position (symmetry) of the CF3 groups; 3CF3-Ga and 3I-Al were structurally characterized. Distortions in the corrole macrocycle imposed by the multiple β-substitution were quantified.
- Zhan, Xuan,Yadav, Pinky,Diskin-Posner, Yael,Fridman, Natalia,Sundararajan, Mahesh,Ullah, Zakir,Chen, Qiu-Cheng,Shimon, Linda J. W.,Mahammed, Atif,Churchill, David G.,Baik, Mu-Hyun,Gross, Zeev
-
supporting information
p. 12279 - 12286
(2019/08/21)
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- Method of removing protective groups of olefins under catalytic action of nickel
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The invention relates to a method of removing protective groups of olefins under the catalytic action of nickel. The method comprises following steps: dissolving olefin containing compounds into an organic solvent, carrying out reactions in the presence of a catalyst, organic ligands, bis(pinacolato)diboron, alkalis, alcohols, and water, wherein the catalyst contains nickel; after reactions, adding excess hydrochloric acid solution (1M) to adjust the pH to the acidic region, stirring the solution until the solution becomes clear; adding water and ethyl acetate to carry out extraction; washing the organic phase by saturated brine, drying the organic phase by anhydrous sodium sulfate, carrying out condensation, and adopting a 200-300 mesh silica gel column to carry out chromatographic separation to obtain compounds that contains alcohols or phenol. The provide method has the advantages that the adopted chemical reagents are common, the primary alkyl halide protective groups of olefins can be removed efficiently, and the method has a good application prospect in the field of organic synthesis and good industrial potential.
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Paragraph 0146-0149
(2019/10/04)
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- Bromine formation in solid NaBr/KNO3 mixture and assay of this reaction via bromination of activated aromatics
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Bromine formation in the mixture of solid NaBr and KNO3 was observed and the process was studied in different acidified organic solvent–water mixtures by monitoring the bromination of acetanilide and other compounds, containing activated aromatic substituents. This assay is based on fast bromination reaction of these aromatic compounds, as differently from the assay of Br2, the brominated aromatics can be easily determined by conventional gas chromatography–mass spectrometry (GC–MS) methods. It was found that bromine was generated autocatalytically on the surface of salt crystals and the reaction was characterized by a lag period, the duration of which depended on reaction conditions, and importantly on the type of the organic solvent in the reaction mixture. As the bromine formation could be easily controlled by reaction conditions, it was suggested that the studied reaction might have practical applications as an environmentally friendly and economically feasible bromination method. It was also shown that the bromination of aromatics followed the mechanism of classical electrophilic aromatic substitution reaction.
- Rahu, Ida,Keki?ev, Ott,J?rv, Jaak,Burk, Peeter
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p. 2893 - 2898
(2018/08/23)
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- Green halogenation reactions for (hetero)aromatic ring systems in alcohol, water, or no solvent
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A new method of brominating aromatic and heteroaromatic ring systems is investigated. The combination of hydrobromic acid as the halogen source, hydrogen peroxide as the oxidant, and ethanol, water, or no solvent are evaluated as greener conditions than those that have been previously published. The new conditions give high yields and good regioselectivity for a variety of substrates when the ring is activated by electron-donating groups or heteroatoms. Phenols, anisole, thiophenes, and pyrrole give comparable or superior results when compared to a traditional bromination by N-bromosuccinimide in tetrahydrofuran. Other nitrogen-containing heterocycles do not react under the conditions because they are protonated and hence deactivated; similarly, substrates with electron-withdrawing groups are not brominated. The reaction is very tolerant of a variety of functional groups.
- Kajorinne, Jessie K.,Steers, Jennifer C.M.,Merchant, Marnie E.,MacKinnon, Craig D.
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p. 1087 - 1091
(2018/11/25)
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- Nitrogen Oxides and Nitric Acid Enable the Sustainable Hydroxylation and Nitrohydroxylation of Benzenes under Visible Light Irradiation
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A new type of waste recycling strategy is described in which nitrogen oxides or nitric acid are directly employed in photocatalyzed hydroxylations and nitrohydroxylations of benzenes. Through these transformations, otherwise costly denitrification can be combined with the synthesis of valuable compounds for various applications.
- Hofmann, Laura Elena,Mach, Leonard,Heinrich, Markus R.
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supporting information
p. 431 - 436
(2017/12/15)
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- Electrochemical Hydroxylation of Arenes Catalyzed by a Keggin Polyoxometalate with a Cobalt(IV) Heteroatom
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The sustainable, selective direct hydroxylation of arenes, such as benzene to phenol, is an important research challenge. An electrocatalytic transformation using formic acid to oxidize benzene and its halogenated derivatives to selectively yield aryl formates, which are easily hydrolyzed by water to yield the corresponding phenols, is presented. The formylation reaction occurs on a Pt anode in the presence of [CoIIIW12O40]5? as a catalyst and lithium formate as an electrolyte via formation of a formyloxyl radical as the reactive species, which was trapped by a BMPO spin trap and identified by EPR. Hydrogen was formed at the Pt cathode. The sum transformation is ArH+H2O→ArOH+H2. Non-optimized reaction conditions showed a Faradaic efficiency of 75 % and selective formation of the mono-oxidized product in a 35 % yield. Decomposition of formic acid into CO2 and H2 is a side-reaction.
- Khenkin, Alexander M.,Somekh, Miriam,Carmieli, Raanan,Neumann, Ronny
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supporting information
p. 5403 - 5407
(2018/04/19)
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- A bromo-capped diruthenium(i,i) N-heterocyclic carbene compound for in situ bromine generation with NBS: Catalytic olefin aziridination reactions
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A bromo-capped metal-metal bonded diruthenium(i,i) complex Ru2(CO)4(PIN)2Br2 (1) (PIN = 1-isopropyl-3-(5,7-dimethyl-1,8-naphthyrid-2-yl)imidazol-2-ylidene) generates bromine with N-bromosuccinimide (NBS) at room temperature. Cycloalkene and stilbene are readily brominated by stoichiometric reactions with 1 and NBS. An analysis of the dibrominated products suggests the formation of cyclic bromonium intermediates indicating in situ Br2 generation. Complex 2, an iodide analogue of 1, is also synthesized. The reaction of 2 with N-iodosuccinimide releases I2, which is confirmed by the starch-iodine test. The catalytic utility of 1 is examined for the bromination of phenol. Catalyst 1, in combination with NBS and base, exhibits regioselectivity towards monobrominated products. Furthermore, efficient olefin aziridination is demonstrated utilizing catalyst 1 in the presence of NBS, K2CO3 and TsNH2.
- Sengupta, Gargi,Pandey, Pragati,De, Subhabrata,Ramapanicker, Ramesh,Bera, Jitendra K.
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supporting information
p. 11917 - 11924
(2018/09/10)
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- Fluorene-based organic compound and application thereof on OLED device
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The invention relates to a fluorene-based organic compound and application thereof on an OLED device. A structure of the compound is that fluorine is connected with a hexatomic ring structure of a benzo hexatomic ring through a carbon-carbon bond, so that material chemical stability is improved and active positions of a branch chain radical are prevented from being exposed through the carbon-carbon bond connection; the whole molecule is a relatively great rigid structure, and has relatively high triplet-state energy level (T1); moreover, steric hindrance is great, rotation is not liable to occur and the three-dimensional space structure is more stable, so that the compound has a relatively high glass transition temperature and relatively high molecule thermal stability; besides, distribution positions of HOMO and LUMO of the compound are separated from each other, so that the fluorene-based organic compound has proper HOMO and LUMO energy level; and after the compound is applied to theOLED device, light-emitting efficiency of the device can be effectively improved, and the service life of the device can be effectively prolonged.
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Paragraph 0102; 0104; 0105
(2018/03/26)
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- Regioselective Halogenation of Arenes and Heterocycles in Hexafluoroisopropanol
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Regioselective halogenation of arenes and heterocycles with N-halosuccinimides in fluorinated alcohols is disclosed. Under mild condition reactions, a wide diversity of halogenated arenes are obtained in good yields with high regioselectivity. Additionally, the versatility of the method is demonstrated by the development of one-pot sequential halogenation and halogenation-Suzuki cross-coupling reactions.
- Tang, Ren-Jin,Milcent, Thierry,Crousse, Benoit
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p. 930 - 938
(2018/01/28)
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- Synthesis, kinetics, and mechanism of bromophenols by N-bromophthalimide in aqueous acetic acid
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The kinetics and mechanism of bromination of phenol and its substituents, viz. 4-chlorophenol, 4-bromophenol, 4-methylphenol, and 4-methoxyphenol by N-bromophthalimide (NBP) in the presence of mercuric acetate in the temperature range of 303–318?K in aqueous acetic acid medium have been investigated. The reaction follows first-order dependence on [NBP] and fractional order dependence of rate on [Phenol]. The activation parameters have been evaluated, and based on the observed kinetic results the probable mechanism has been proposed. Observed kinetic features and Hammett's reaction constant (ρ) suggests that bromination occurs through electrophilic substitution of bromonium ion (Br+) into the aromatic ring in the transition state. Large negative entropy of activation values probably suggests the rigid nature of transition state.
- Anjaiah, Birla,Prameela, Kethavath,Srinivas, Pabba,Rajanna, Kamatala Chinna
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p. 804 - 812
(2018/09/11)
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- Deprotection of durable benzenesulfonyl protection for phenols — efficient synthesis of polyphenols
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A robust protection method for phenol was demonstrated by the use of durable benzenesulfonyl group, which survives various harsh reaction conditions using Grignard reagent, organolithium reagent, metal alkoxide, phosgene, mineral, and Lewis acids. A facile deprotection condition utilizing pulverized KOH (5 equiv) and t-BuOH (10 equiv) in hot toluene makes this protocol as a practical method, which can be applied to the multistep synthesis of biologically and medicinally important polyphenol compounds.
- Alam, Mohammad Shariful,Koo, Sangho
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supporting information
p. 247 - 254
(2018/01/08)
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- Green Photoorganocatalytic Synthesis of Phenols from Arylboronic Acids
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A green and cheap protocol for the photocatalytic hydroxylation of arylboronic acids is presented. 2,2-Dimethoxy-2-phenylacetophenone proved to be the best photoinitiator, among a range of organocatalysts in promoting this reaction. This photocatalytic protocol can be expanded into a wide substrate scope of aromatic boronic acids bearing various functional groups, leading to the corresponding phenols in good to high yields under mild reaction conditions, which include water as solvent, light irradiation provided from standard light-bulbs at room temperature.
- Sideri, Ioanna K.,Voutyritsa, Errika,Kokotos, Christoforos G.
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supporting information
p. 1324 - 1328
(2017/12/06)
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- Regioselective monobromination of aromatics via a halogen bond acceptor-donor interaction of catalytic thioamide and N-bromosuccinimide
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Regioselective monobromination of various aromatics was achieved at room temperature using N-bromosuccinimide and 5 mol% of thioamides in acetonitrile. With thiourea as catalyst, activated aromatics, such as anisole, acetanilide, benzamide and phenol analogues containing electron donating or withdrawing groups, were brominated with high regioselectivity. Room temperature brominations of weakly activated aromatics and deactivated 9-fluorenone were accomplished by 5 mol% thioacetamide, higher substrates concentrations and longer reaction times. A backbonding of the bromine lone pairs with the π*of C[dbnd]S group and a halogen bond between the halogen bond donor bromine and the halogen bond acceptor sulfur of the thioamide are thought to be the principal interactions and cause of N-bromosuccinimide activation.
- Bovonsombat, Pakorn,Teecomegaet, Pattaradra,Kulvaranon, Panisanun,Pandey, Aditi,Chobtumskul, Kittithorn,Tungsirisurp, Sireethorn,Sophanpanichkul, Punyanuch,Losuwanakul, Satreerat,Soimaneewan, Dechathon,Kanjanwongpaisan, Patcharida,Siricharoensang, Pornpawit,Choosakoonkriang, Sirirat
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p. 6564 - 6572
(2017/10/17)
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- Chemoselective oxidation of aryl organoboron systems enabled by boronic acid-selective phase transfer
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We report the direct chemoselective Brown-type oxidation of aryl organoboron systems containing two oxidizable boron groups. Basic biphasic reaction conditions enable selective formation and phase transfer of a boronic acid trihydroxyboronate in the presence of boronic acid pinacol (BPin) esters, while avoiding speciation equilibria. Spectroscopic investigations validate a base-promoted phase-selective discrimination of organoboron species. This phenomenon is general across a broad range of organoboron compounds and can also be used to invert conventional protecting group strategies, enabling chemoselective oxidation of BMIDA species over normally more reactive BPin substrates. We also demonstrate the selective oxidation of diboronic acid systems with chemoselectivity predictable a priori. The utility of this method is exemplified through the development of a chemoselective oxidative nucleophile coupling.
- Molloy, John J.,Clohessy, Thomas A.,Irving, Craig,Anderson, Niall A.,Lloyd-Jones, Guy C.,Watson, Allan J. B.
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p. 1551 - 1559
(2017/02/10)
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- Photocatalytic benzene and benzene derivative direct hydroxylation or amination method
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The invention discloses a photocatalytic benzene and benzene derivative direct hydroxylation or amination method. The method is characterized by comprising the following steps: (1) adding a photo-sensitizer and a cobalt catalyst into a solvent to obtain a solution (A); (2) adding benzene (or benzene derivatives), water, ammonia gas, and amide derivatives (or sulfonamide derivatives) into the solution (A) to obtain a solution (B); and (3) in a N2 (or Ar) environment, radiating the solution (B) by a medium pressure mercury lamp, a high pressure mercury lamp, a xenon lamp, or an LED lamp to obtain phenols or amines and H2. For the first time, a photo-sensitizer and a cobalt catalyst are combined and applied to photocatalytic hydroxylation and amination of benzene. The conditions of the method are mild, light is taken as the driving energy, no oxidant is added, the only byproduct is H2, and the whole process is green, concise, and efficient. High selective benzene one-step hydroxylation to generate phenol or high selective phenol/benzene one-step amination to generate aniline is realized, and the method can be applied to the production of phenol and aniline.
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Paragraph 0100-0101
(2017/11/29)
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- Direct hydroxylation of benzene and aromatics with H2O2 catalyzed by a self-assembled iron complex: Evidence for a metal-based mechanism
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An iminopyridine Fe(ii) complex, easily prepared in situ by self-assembly of cheap and commercially available starting materials (2-picolylaldehyde, 2-picolylamine, and Fe(OTf)2 in a 2 : 2 : 1 ratio), is shown to be an effective catalyst for the direct hydroxylation of aromatic rings with H2O2 under mild conditions. This catalyst shows a marked preference for aromatic ring hydroxylation over lateral chain oxidation, both in intramolecular and intermolecular competitions, as long as the arene is not too electron poor. The selectivity pattern of the reaction closely matches that of electrophilic aromatic substitutions, with phenol yields and positions dictated by the nature of the ring substituent (electron-donating or electron-withdrawing, ortho-para or meta-orienting). The oxidation mechanism has been investigated in detail, and the sum of the accumulated pieces of evidence, ranging from KIE to the use of radical scavengers, from substituent effects on intermolecular and intramolecular selectivity to rearrangement experiments, points to the predominance of a metal-based SEAr pathway, without a significant involvement of free diffusing radical pathways.
- Capocasa, Giorgio,Olivo, Giorgio,Barbieri, Alessia,Lanzalunga, Osvaldo,Di Stefano, Stefano
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p. 5677 - 5686
(2017/12/07)
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- Design, Synthesis, and Evaluation of a Series of Novel Benzocyclobutene Derivatives as General Anesthetics
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In the present work, a series of structurally novel benzocyclobutene derivatives were identified as general anesthetics through the loss of righting reflex (LORR) experiment on mice. Our initial efforts found compound 1a with a fused four-membered ring on the 2,3-position of the phenol ring could significantly improve the safety profile. Further SAR study revealed that small hydrogen bond acceptor (HBA) groups are optimal for good ED50 along with much broader therapeutic windows, such as compounds 16b and 17. Present work demonstrates the superiority of this novel benzocyclobutene scaffold.
- Zhang, Chen,Li, Fangqiong,Yu, Yan,Huang, Anbang,He, Ping,Lei, Ming,Wang, Jianmin,Huang, Longbin,Liu, Zhenhong,Liu, Jianyu,Wei, Yonggang
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p. 3618 - 3625
(2017/05/19)
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- A competing, dual mechanism for catalytic direct benzene hydroxylation from combined experimental-DFT studies
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A dual mechanism for direct benzene catalytic hydroxylation is described. Experimental studies and DFT calculations have provided a mechanistic explanation for the acid-free, TpxCu-catalyzed hydroxylation of benzene with hydrogen peroxide (Tpx = hydrotrispyrazolylborate ligand). In contrast with other catalytic systems that promote this transformation through Fenton-like pathways, this system operates through a copper-oxyl intermediate that may interact with the arene ring following two different, competitive routes: (a) electrophilic aromatic substitution, with the copper-oxyl species acting as the formal electrophile, and (b) the so-called rebound mechanism, in which the hydrogen is abstracted by the Cu-O moiety prior to the C-O bond formation. Both pathways contribute to the global transformation albeit to different extents, the electrophilic substitution route seeming to be largely favoured.
- Vilella, Laia,Conde, Ana,Balcells, David,Mar Díaz-Requejo,Lledós, Agustí,Pérez, Pedro J.
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p. 8373 - 8383
(2017/11/27)
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- Facile and metal-free synthesis of phenols from benzaldoxime and diaryliodonium salts
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A metal-free, base-promoted facile synthesis of phenol derivatives utilising diaryliodonium salts as the aryl source and benzaldoxime as the hydroxide surrogate has been developed. The reaction is fast and shows good substrate compatibility, giving the corresponding products in good to excellent yields. A gram-scale synthesis of phenols utilising this protocol has also been achieved.
- Zhou, Yongsheng
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p. 591 - 593
(2017/11/14)
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- 8,10,12 as nanoreactors for non-enzymatic introduction of: Ortho, meta or para -hydroxyl groups to aromatic molecules
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Traditional electrophilic bromination follows long established "rules": electron-withdrawing substituents cause bromination selective for meta positions, whereas electron-donating substituents favor ortho and para bromination. In contrast, in the [PhSiO1.5]8,10,12 silsesquioxanes, the cages act as bulky, electron withdrawing groups equivalent to CF3; yet bromination under mild conditions, without a catalyst, greatly favors ortho substitution. Surprisingly, ICl iodination without a catalyst favors (>90%) para substitution [p-IC6H4SiO1.5]8,10,12. Finally, nitration and Friedel-Crafts acylation and sulfonylation are highly meta selective, >80%. In principle, the two halogenation formats coupled with the traditional electrophilic reactions provide selective functionalization at each position on the aromatic ring. Furthermore, halogenation serves as a starting point for the synthesis of two structural isomers of practical utility, i.e. in drug prospecting. The o-bromo and p-iodo compounds are easily modified by catalytic cross-coupling to append diverse functional groups. Thereafter, F-/H2O2 treatment cleaves the Si-C bonds replacing Si with OH. This represents a rare opportunity to introduce hydroxyl groups to aromatic rings, a process not easily accomplished using traditional organic synthesis methods. The as-produced phenol provides additional opportunities for modification. Each cage can be considered a nanoreactor generating 8-12 product molecules. Examples given include syntheses of 4,2′-R,OH-stilbenes and 4,4′-R,OH-stilbenes (R = Me, CN). Unoptimized cleavage of the Br/I derivatives yields 55-85% phenol. Unoptimized cleavage of the stilbene derivatives yields 35-40% (3-5 equivalents of phenol) in the preliminary studies presented here. In contrast, meta R-phenol yields are 80% (7-10 mol per cage).
- Bahrami, Mozhgan,Zhang, Xingwen,Ehsani, Morteza,Jahani, Yousef,Laine, Richard M.
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supporting information
p. 8797 - 8808
(2017/07/22)
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- A mild copper catalyzed method for the selective deprotection of aryl allyl ethers
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Copper boryl reagents enable the selective cleavage of aryl allyl ethers to the corresponding phenols in good to moderate yields.
- Hemming, David S.,Talbot, Eric P.,Steel, Patrick G.
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supporting information
p. 17 - 20
(2016/12/23)
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- The Catalyst-Controlled Regiodivergent Chlorination of Phenols
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Different catalysts are demonstrated to overcome or augment a substrate's innate regioselectivity. Nagasawa's bis-thiourea catalyst was found to overcome the innate para-selectivity of electrophilic phenol chlorination, yielding ortho-chlorinated phenols that are not readily obtainable via canonical electrophilic chlorinations. Conversely, a phosphine sulfide derived from 2,2′-Bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) was found to enhance the innate para-preference of phenol chlorination.
- Maddox, Sean M.,Dinh, Andrew N.,Armenta, Felipe,Um, Joann,Gustafson, Jeffrey L.
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supporting information
p. 5476 - 5479
(2016/11/17)
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- A dinuclear iron(II) complex bearing multidentate pyridinyl ligand: Synthesis, characterization and its catalysis on the hydroxylation of aromatic compounds
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A dinuclear iron(II) complex Fe2L2(μ2-Cl)2Cl2 (L = N,N-bis(pyridin-2-ylmethyl)prop-2-yn-1-amine) was prepared and fully characterized by UV–Vis spectroscopy, elemental analysis, electrochemical analysis and X-ray single crystal diffraction analysis. The catalytic activity of the complex was assessed for the hydroxylation of aromatic compounds by using aqueous H2O2 as an oxidant in acetonitrile. The catalytic system was applicable in a wide range of substrates including aromatic compounds with both electron-donating and electron-withdrawing substituents and showed moderate to good catalytic activity and selectivity in the oxidation reactions. Particularly, in the case of benzene the selectivity of phenol achieve to 74% with the reaction conversion of 24.8%.
- Gu, Erxing,Zhong, Wei,Ma, Hongxia,Xu, Beibei,Wang, Hailong,Liu, Xiaoming
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p. 159 - 165
(2018/03/29)
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- Sustainable oxidations with air mediated by gallic acid: Potential applicability in the reutilization of grape pomace
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Gallic acid converts atmospheric oxygen into hydrogen peroxide, which is able to oxidize arylboronic acids as a proof of concept of sustainable oxidations. Moreover, tannic acid and grape pomace extract are also able to perform oxidations with air. Therefore this work unleashes an alternative method for reutilization and valorization of bio-wastes rich in tannins.
- Scoccia, Jimena,Perretti, Marcelle D.,Monzón, Diego M.,Crisóstomo, Fernando P.,Martín, Víctor S.,Carrillo, Romen
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supporting information
p. 2647 - 2650
(2016/06/06)
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- Thermal Protodeboronation of hydroxyarene Boronic Acids and Its Application to ortho- and meta- Functionalization of hydroxyarene Using Boronic Acids as Blocking and Directing Groups
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The present invention refers to hydroxy arene boron acid compounds that thermal de borohydride of phenolic compounds using functional groups in ortho-or meta-position with hydroxy [...] manufacturing method relates to, more particularly boron position and outputs ortho of phenol then substituted acid, ortho-or meta-position boron arene hydroxy then introduced to a functional groups in making and compounds, thermal de using borohydride said boron acid by removing phenol from ortho-or meta-position functional groups in have been introduced method for preparing the compounds of arene hydroxy relates to. Manufacturing method of arene compound hydroxy the present invention according to such as iridium or a palladium metal catalyst-free, a stronger acid than the acid or base conditions, a low-temperature reaction acid and acetic anhydride the microbeam generating reactions, by causing or permitting a condition without requiring a step of client and, simply phenol from ortho-or meta-position for introducing functional groups to hydroxy arene compound can be produced.
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Paragraph 0126-0128
(2016/10/27)
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- Direct hydroxylation of arenes with O2 catalyzed by V@CN catalyst
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A vanadium doped graphitic carbon nitride catalyst has been prepared and used for the direct hydroxylation of arenes with O2. Substituted arenes with electron-withdrawing groups such as CN, NO2, COOH, CF3, and COCH3 were oxygenated to the corresponding phenols in moderate yields. The catalyst also proved applicable for the hydroxylation of aromatic halides (F, Cl, and Br) with O2.
- Li, Yan,Li, Bing,Chen, Ting,Zhou, Zhicheng,Wang, Jun,Huang, Jun
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p. 1086 - 1092
(2015/07/01)
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- The Hydroxylation of Aromatics with Oxygen by Vanadium Catalysts Supported on N-doped Carbon Materials
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Vanadium catalysts supported on N-doped carbon materials (CN) were prepared and the catalyst VOSiW showed high activity for the hydroxylation of various aromatics with O2. Aromatics with electron-withdrawing groups such as CN, NO2, COOH, CF3, COCH3 and aromatic halides (F, Cl and Br) were oxygenated to the corresponding phenols in considerable yields. The CN materials were not only indispensable for the reusability of the vanadium catalyst VOSiW, but also favorable to the high catalytic activity. The VOSiW catalyst is ready for the hydroxylation of aromatics with O2 as both V4+ and V5+ species are coexisted in the VOSiW catalyst.
- Li, Yan,Li, Bing,Geng, Longfei,Wang, Jun,Wang, Yong,Huang, Jun
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p. 1014 - 1021
(2015/08/04)
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- Sono-bromination of aromatic compounds based on the ultrasonic advanced oxidation processes
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A novel, mild "sono-halogenation" of various aromatic compounds with potassium halide was investigated under ultrasound in a biphasic carbon tetrachloride/water medium. The feasibility study was first undertaken with the potassium bromide and then extended to chloride and iodide analogues. This methodology could be considered as a new expansion of the ultrasonic advanced oxidation processes (UAOPs) into a synthetic aspect as the developed methodology is linked to the sonolytic disappearance of carbon tetrachloride. Advantages of the present method are not only that the manipulation of the bromination is simple and green, but also that the halogenating agents used are readily available, inexpensive, and easy-handling.
- Fujita, Mitsue,Lévêque, Jean-Marc,Komatsu, Naoki,Kimura, Takahide
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p. 247 - 251
(2015/06/08)
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