- Application of Ionic Liquid Halide Nucleophilicity for the Cleavage of Ethers: A Green Protocol for the Regeneration of Phenols from Ethers
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We have used the high nucleophilicity of bromide ion in the form of the ionic liquid, 1-n-butyl-3-methylimidazolium bromide ([bmim][Br]), for the nucleophilic displacement of an alkyl group to regenerate a phenol from the corresponding aryl alkyl ether. Using 2-methoxynaphthalene (1) as a model compound, we found that the combination of ionic liquid [bmim][Br] and p-toluenesulfonic acid with warming effected demethylation in 14 h, affording the desired product 2-naphthol (2) in good yield (97%). Various other protic acids (MsOH, hydrochloric acid (35%), dilute sulfuric acid (50%)) could be used as a proton source in this demethylation reaction. Under the same conditions, cleavage of alkyl alkyl ether 2-(3-methoxypropyl)naphthalene yielded mixture of corresponding 2-(3-bromopropyl)naphthalene and 2-(3-hydroxypropyl)naphthalene. Dealkylation of various aryl alkyl ethers could also be achieved using significantly reduced (i.e., stoichiometric) amounts of concentrated hydrobromic acid (47%) in the ionic liquid. Both procedures afforded the desired products in moderate to good yield; however, cleavage of aryl alkyl cyclic ether, 2,3-dihydrobenzofuran, resulted in low yield of the desired product o-2-bromoethylphenol. The convenience of this method for ether cleavage and its effectiveness using only a moderate excess of hydrobromic acid make it attractive as a green chemical method.
- Boovanahalli, Shanthaveerappa K.,Kim, Dong Wook,Chi, Dae Yoon
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- Suspension Ring-Opening Metathesis Polymerization: The Preparation of Norbornene-Based Resins for Application in Organic Synthesis
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A series of norbornene-based resin beads were obtained by aqueous suspension ring-opening metathesis polymerization (ROMP) and used as polymeric supports for organic synthesis. These resins were prepared from norbornene, norborn-2-ene-5-methanol, and cross-linkers such as bis(norborn-2-ene-5-methoxy)alkanes, di(norborn-2-ene-5-methyl)ether, and 1,3-di(norborn-2-ene-5-methoxy)benzene. The resulting unsaturated ROMP (U-ROMP) resins containing olefin repeat units were chemically modified using hydrogenation, hydrofluorination, chlorination, and bromination reactions to produce saturated ROMP resins with different chemical and physical properties. The hydrogenated ROMP (H-ROMP) resin was found to be highly resistant to acidic, basic, Lewis acid, and Birch reduction conditions and was assessed as a polymeric support in a series of solid-phase synthetic applications. The H-ROMP resin was found to have superior performance compared to polystyrene-divinylbenzene (PS-DVB) copolymers in aromatic nitration and acylation reactions. In a conventional five-step solid-phase synthesis of a hydantoin, similar results were obtained for both the H-ROMP and PS-DVB resins. The U-ROMP resin was also shown to be effective in the solid-phase syntheses of benzimidazoles and benzimidazolones.
- Lee, Byoung Se,Mahajan, Suresh,Clapham, Bruce,Janda, Kim D.
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- Modulation of reactivity of singlet radical pair in continuous flow: Photo-Fries rearrangement
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Photo-Fries rearrangement of phenyl benzoate is studied using continuous flow for modulating the reactivity of singlet radical pair by changing the viscosity of the solvent. The effect of flow and proximity of the reactants with the light source on the reactivity of radical pair, formed from singlet excited state was investigated in details. In non-viscous solvent, the results from flow synthesis were comparable to batch reactor. In viscous solvents, selectivity of ortho- and para-isomers (o-/p- isomer) of the product could be controlled by changing viscosity as well as the flow rate. Using flow synthesis, ortho- and para-isomer ratio was obtained as high as 8.45 which are twice as compared to batch experiment with in fraction of residence time.
- Karjule, Neeta,Sharma, Mrityunjay K.,Nithyanandhan, Jayaraj,Kulkarni, Amol A.
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- Synthesis of benzophenones from geminal biaryl ethenes using m-chloroperbenzoic acid
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The oxidation of geminal biaryl ethenes 3 and 1,3-enynes 5 using m-chloroperbenzoic acid in dichloromethane at room temperature presents a catalyst-free approach for the synthesis of functionalized benzophenones 4 and ynones 6, respectively.
- Singh, Fateh V.,Milagre, Humberto M.S.,Eberlin, Marcos N.,Stefani, Helio A.
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- Panel of New Thermostable CYP116B Self-Sufficient Cytochrome P450 Monooxygenases that Catalyze C?H Activation with a Diverse Substrate Scope
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The ability of cytochrome P450 monooxygenases to catalyse a wide variety of synthetically challenging C?H activation reactions makes them highly desirable biocatalysts both for the synthesis of chiral intermediates and for late-stage functionalisations. However, P450s are plagued by issues associated with poor expression, solubility and stability. Catalytically self-sufficient P450s, in which the haem and reductase domains are fused in a single protein, obviate the need for additional redox partners and are attractive as biocatalysts. Here we present a panel of natural self-sufficient P450s from thermophilic organisms (CYP116B65 from A. thermoflava, CYP116B64 from A. xiamenense, CYP116B63 from J. thermophila, CYP116B29 from T. bispora and CYP116B46 from T. thermophilus). These P450s display enhanced expression and stability over their mesophilic homologues. Activity profiling of these enzymes revealed that each P450 displayed a different fingerprint in terms of substrate range and reactivity that cover reactions as diverse as hydroxylation, demethylation, epoxidation and sulfoxidation. The productivity of the bio-transformation of diclofenac to produce the 5-hydroxy metabolite increased 42-fold using the thermostable P450-AX (>0.5 g L?1 h?1) compared to the P450-RhF system reported previously. In conclusion, we have generated a toolkit of thermostable self-sufficient P450 biocatalysts with a broad substrate range and reactivity.
- Tavanti, Michele,Porter, Joanne L.,Sabatini, Selina,Turner, Nicholas J.,Flitsch, Sabine L.
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- Benzoylation in room temperature ionic liquids
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Aromatic substrates were efficiently benzoylated with benzotrichloride using ionic liquid as the reaction medium.
- Rebeiro, Geeta L.,Khadilkar, Bhushan M.
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- Integrative Photoreduction of CO2 with Subsequent Carbonylation: Photocatalysis for Reductive Functionalization of CO2
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Efficient conversion of CO2 into fuels and chemicals with solar energy would be promising, but also faces great challenge. In this context, we describe the photoreductive functionalization of CO2 to construct new C?C, C?N, and C?O bonds through the respective Pd-catalyzed Suzuki carbonylation, aminocarbonylation, and alkoxycarbonylation of aryl iodides with CO in situ generated through the photoreduction of CO2. This protocol opens up an alternative avenue for CO2 utilization by harnessing solar energy.
- He, Xing,Cao, Yu,Lang, Xian-Dong,Wang, Ning,He, Liang-Nian
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- Synthesis of 5-(4′-aroyl)-aryloxy methyl-4H-(1,2,4)-triazolin-3-thiol and their biological activity
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5-(4′-aroyl)-aryloxy methyl-4H-1,2, 4)-triazolin-3-thiols were synthesized by using substituted phenyl benzoates as the starting material. Phenyl benzoates on Fries rearrangement gave p-hydroxy benzophenones which on treatment with ethyl bromoacetate in presence of anhydrous potassium carbonate and dry acetone gave corresponding benzoyl phenyloxy esters in excellent yield. Esters were refluxed with thiosemicarbazide in presence of acetic anhydride gave cyclized title compounds. Supports for the structures of the synthesized compounds have been provided by their elemental analysis and spectral data. The newly synthesized compounds were screened for antibacterial and antifungal activities.
- Sudha,Shashikanth,Khanum, Shaukath Ara
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- Photochemical rearrangement of phenyl benzoate in the presence of cyclodextrins and amylose
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The photorearrangement of phenyl benzoate in aqueous medium is changed in the presence of cyclodextrins or amylose; the ortho/para migration ratio is altered in favor of the para position.
- Chenevert,Voyer
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- One-step reaction of friedel-crafts acylation and demethylation of aryl-methyl ethers catalyzed by ytterbium(III) triflate
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Catalytic amount of ytterbium(III) inflate [Yb(OTf)3] has been used to catalyze Friedel-Crafts acylation and demethylation of aryl-methyl ethers in one-step reaction to produce hydroxyacylphenones with moderate yields under mild conditions.
- Su, Weike,Jin, Can
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- One-step hydroxylation of aryl and heteroaryl fluorides using mechanochemistry
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Simple use of KOH allows the direct F to OH exchange of aromatic and heteroaromatic substrates under mechanochemical conditions. The reaction is performed in the absence of solvent with potassium hydroxide as OH source. As a result, this approach is both more atom economical and environmentally friendly than previously described methods for this transformation.
- Braje, Wilfried,Geneste, Hervé,Rodrigo, Eduardo,Walter, Magnus W.,Wiechert, Rainer
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supporting information
p. 1469 - 1473
(2022/03/07)
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- Substituent and Surfactant Effects on the Photochemical Reaction of Some Aryl Benzoates in Micellar Green Environment?
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In this study, we carried out preparative and mechanistic studies on the photochemical reaction of a series of p-substituted phenyl benzoates in confined and sustainable micellar environment. The aim of this work is mainly focused to show whether the nature of the surfactant (ionic or nonionic) leads to noticeable selectivity in the photoproduct formation and whether the electronic effects of the substituents affect the chemical yields and the rate of formation of the 5-substituted-2-hydroxybenzophenone derivatives. Application of the Hammett linear free energy relationship (LFER) on the rate of formation of benzophenone derivatives, on the lower energy band of the UV-visible absorption spectra of the aryl benzoates and 5-substituted-2-hydroxybenzophenone derivatives allows a satisfactory quantification of the substituent effects. Furthermore, UV-visible and 2D-NMR (NOESY) spectroscopies have been employed to measure the binding constant Kb and the location of the aryl benzoates within the hydrophobic core of the micelle. Finally, TD-DFT calculations have been carried out to estimate the energies of the absorption bands of p-substituted phenyl benzoates and 5-substituted-2-hydroxybenzophenone derivatives providing good linear correlation with those values measured experimentally.
- Siano, Gastón,Crespi, Stefano,Bonesi, Sergio M.
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p. 1298 - 1309
(2021/05/07)
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- Discovery and characterization of a novel perylenephotoreductant for the activation of aryl halides
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To develop a photocatalyst with catalytical activity for substrates with low reactivities is always highly desired. Herein, based on the principle of structure–property relationships, we rationally designed the natural product cercosporin, the naturally occurring perylenequinonoid pigment, to develop a novel organic perylenephotoreductant, hexacetyl reduced cercosporin (HARCP), through structural manipulation. Compared with cercosporin, HARCP shows prominent electrochemical and photophysical characteristics with greatly improved photoreductive activity, fluorescence lifetime and fluorescence quantum yield. These properties allowed HARCP as a powerful photoreductant to efficiently realize a series of benchmark reactions, including photoreduction, alkoxylation and hydroxylation to construct C–H and C–O bonds using aryl halides as substrates under mild conditions, all of which have never been achieved by the same photocatalyst. Thus, this study well supports the notion that the principle between structural manipulation and photocatalytic activity is of great significance to design customized photocatalysts for photoredox chemistry.
- Guo, Baodang,Huang, Shuping,Li, Jia,Li, Min,Liu, Xuanzhong,Rao, Yijian,Wu, Yawen,Yin, Huimin,Yuan, Zhenbo,Zhang, Yan
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p. 111 - 120
(2021/06/16)
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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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- PhSe(O)OH/NHPI-catalyzed oxidative deoximation reaction using air as oxidant
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A novel oxidative deoximation method was developed in this article. Compared with the reported organoselenium-catalyzed oxidative deoximation reaction, this reaction employed N-hydroxyphthalimide (NHPI) as the co-catalyst, so that the oxidative deoximation reaction could utilize air as oxidant in the green DMC solvent under mild reaction conditions. Control experiments and X-ray photoelectron spectroscopy (XPS) analysis results indicated that NHPI was essential for activating the catalytic organoselenium species. It could accelerate the activation of molecular oxygen in air to promote the reaction process. The reaction can avoid metal residues in product and is of potential application values in pharmaceutical industry due to the transition metal-free process.
- Shi, Yaocheng,Wang, Feng,Yang, Chenggen,Yu, Lei
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- Application of Electron-Rich Covalent Organic Frameworks COF-JLU25 for Photocatalytic Aerobic Oxidative Hydroxylation of Arylboronic Acids to Phenols
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Visible-light-driven organic reactions are environmentally friendly green chemical transformations among which photosynthetic oxidative hydroxylation of arylboronic acids to phenols has attracted increasing research interest during the very recent years. Given the efficiency and reusability of heterogeneous catalysts, COF-JLU25, an electron-rich COF-based photocatalyst constructed by integrating electron-donating blocks 1,3,6,8-tetrakis(4-aminophenyl)pyrene (PyTA) and 4-[4-(4-formylmethyl)-2,5-dimethoxyphenyl] benzaldehyde (TpDA), was selected as a photocatalyst for the oxidative hydroxylation of arylboronic acids. In our studies, COF-JLU25 demonstrated excellent photocatalytic activity with high efficiency, robust reusability, and low catalyst loading, showcasing an application potential of previously underexplored COF-based photocatalyst composed solely of electron-rich units.
- Xiao, Guangjun,Li, Wenqian,Chen, Tao,Hu, Wei-Bo,Yang, Hui,Liu, Yahu A.,Wen, Ke
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supporting information
p. 3986 - 3991
(2021/03/29)
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- Radical-anion coupling through reagent design: hydroxylation of aryl halides
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The design and development of an oxime-based hydroxylation reagent, which can chemoselectively convert aryl halides (X = F, Cl, Br, I) into phenols under operationally simple, transition-metal-free conditions is described. Key to the success of this approach was the identification of a reducing oxime anion which can interact and couple with open-shell aryl radicals. Experimental and computational studies support the proposed radical-nucleophilic substitution chain mechanism.
- Chechik, Victor,Greener, Andrew J.,James, Michael J.,Oca?a, Ivan,Owens-Ward, Will,Smith, George,Ubysz, Patrycja,Whitwood, Adrian C.
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p. 14641 - 14646
(2021/11/17)
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- Iodine Promoted Conversion of Esters to Nitriles and Ketones under Metal-Free Conditions
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We report a novel strategy to prepare valuable nitriles and ketones through the conversion of esters under metal-free conditions. By using the I2/PCl3 system, various substrates including aliphatic and aromatic esters could react with acetonitrile and arenes to afford the desired products in good to excellent yields. This method is compatible with a number of functional groups and provides a simple and practical approach for the synthesis of nitrile compounds and aryl ketones.
- Xiao, Jing,Guo, Fengzhe,Li, Yinfeng,Li, Fangshao,Li, Qiang,Tang, Zi-Long
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p. 2028 - 2035
(2021/02/03)
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- Synthesis method of ultraviolet absorber 4-n-hexyloxybenzophenone
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The invention relates to the technical field of synthesis of 4-n-hexyloxybenzophenone and discloses a synthesis method of ultraviolet absorber 4-n-hexyloxybenzophenone. The method comprises the following steps: adding anisole into a reaction kettle filled with dichloroethane, adding aluminum trichloride at room temperature, then uniformly stirring and dissolving, dropwise adding a benzoyl chloridemixed solution dissolved in dichloroethane, after dropping, reacting for 40 minutes at room temperature, raising the temperature to 50/55 DEG C and reacting for 120 minutes, after the reaction is finished, dropwise adding the reaction liquid into dilute acid for acidolysis, adding alcohol for crystallization to obtain 4-hydroxybenzophenone, adding self-made CatAP, heating to 40 DEG C, dropwise adding an NAOH solution, heating to 60/65 DEG C after the dropwise addition is finished, reacting for 3 hours, then cooling to 25 DEG C, centrifuging to obtain a crude product, and finally recrystallizing the crude product with alcohol to obtain a finished product. According to the synthesis of the ultraviolet light absorber 4-n-hexyloxybenzophenone, the product content of the 4-n-hexyloxybenzophenone reaches 99.5% or above, the reaction conditions are mild, the raw material cost is reduced, the energy consumption is reduced, and the economic benefit is obvious.
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Paragraph 0037-0050
(2020/12/05)
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- SuFEx Activation with Ca(NTf2)2: A Unified Strategy to Access Sulfamides, Sulfamates, and Sulfonamides from S(VI) Fluorides
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A method to activate sulfamoyl fluorides, fluorosulfates, and sulfonyl fluorides with calcium triflimide and DABCO for SuFEx with amines is described. The reaction was applied to a diverse set of sulfamides, sulfamates, and sulfonamides at room temperature under mild conditions. Additionally, we highlight this transformation to parallel medicinal chemistry to generate a broad array of nitrogen-based S(VI) compounds.
- Am Ende, Christopher W.,Ball, Nicholas D.,Bellenger, Justin,Butler, Todd W.,Carneiro, Sabrina N.,Dutra, Jason K.,Gu, Junha,Khasnavis, Samuel R.,Kwan, Sabrina C.,Mahapatra, Subham,Vetelino, Beth C.,Woroch, Cristian P.
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supporting information
(2020/06/05)
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- Bimetallic photoredox catalysis: Visible light-promoted aerobic hydroxylation of arylboronic acids with a dirhodium(ii) catalyst
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We report the use of a rhodium(II) dimer in visible light photoredox catalysis for the aerobic oxidation of arylboronic acids to phenols under mild conditions. Spectroscopic and computational studies indicate that the catalyst Rh2(bpy)2(OAc)4 (1) undergoes metal-metal to ligand charge transfer upon visible light irradiation, which is responsible for catalytic activity. Further reactivity studies demonstrate that 1 is a general photoredox catalyst for diverse oxidation reactions.
- Campbell, Michael G.,Chuang, Gary Jing,Liu, Ming-Lun,Miura-Stempel, Emily,Tu, Jing-Wen,Yang, Hsiang-Ming
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p. 2040 - 2047
(2020/03/13)
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- Acid-Promoted Intramolecular Decarbonylative Coupling Reactions of Unstrained Ketones: A Modular Approach to Synthesis of Acridines and Diaryl Ketones
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Herein, we reported Lewis acid-or Br?nsted acid-promoted intramolecular C(sp2)-C(sp2) bond cleavage and a novel C(sp2)-C(sp2) bond-forming cascade reaction to synthesize the acridine motif. The metal-free oxidation of the alkyne motif generated the in situ ketone group extracted via a decarbonylation reaction. The mechanistic studies revealed that the electrophilic N-iodo species triggered key decarbonylation reactions via consecutive dearomatization/aromatization reactions. In addition, we exploited this acid-promoted C-C bond activation system with internal alkynes to synthesize bis(heteroaryl) ketones.
- Dhandabani, Ganesh Kumar,Shih, Chia-Ling,Wang, Jeh-Jeng
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supporting information
p. 1955 - 1960
(2020/03/04)
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- Efficient solvent- And temperature-tuned access to aldoxime ethers and phenolic functions by Pd-catalyzed C-O cross-coupling of aldoximes with aryl bromides and bromo-chalcones
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A single method with a functionality switching option was developed for the first time for the Pd-catalyzed C-O cross-coupling of aryl bromides and bromo-chalcones with aldoximes. The ligand tBuXPhos (L2) was found to be an effective supporting ligand for the Pd-catalyzed coupling of aldoximes with bromo coupling partners. The functionality switching from oxime ethers to a phenolic or hydroxy group was driven by solvent or temperature. This method offers the products in good to excellent yields in short reaction times.
- Reeta,Rangarajan,Kaushik, Kumar,Singh, Rishi Pal,Singh, Manjula,Singh, Raj Pal
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supporting information
p. 1326 - 1336
(2020/02/11)
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- Selectivity in the photo-fries rearrangement of some aryl benzoates in green and sustainable media. Preparative and mechanistic studies
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Irradiation of a series of p-substituted aryl benzoates under N2 atmosphere in homogeneous and micellar media was investigated by means of steady-state condition and of time-resolved spectroscopy. A notable selectivity in favor of the 2-hydroxybenzophenone derivatives was observed in micellar media. The benzophenone derivatives were the main photoproduct. On the other hand, in homogeneous media (cyclohexane, acetonitrile, and methanol) the observed product distribution was entirely different, viz. substituted 2-hydroxybenzophenones, p-substituted phenols, benzyl and benzoic acid were found. The binding constants in the surfactant were also measured and NOESY experiments showed that the aryl benzoates were located in the hydrophobic core of the micelle. Laser flash photolysis experiments led to the characterization of both p-substituted phenoxy radical and substituted 2-benzoylcyclohexadienone transients in homogeneous and micellar environment.
- Siano, Gastón,Bonesi, Sergio M.,Crespi, Stefano,Mella, Mariella
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p. 4338 - 4352
(2019/05/01)
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- Visible Light-Mediated [2 + 2] Cycloaddition Reactions of 1,4-Quinones and Terminal Alkynes
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A single-step synthesis of 4-hydroxy-functionalized bi-aryl and aryl/alkyl ketones via oxidative coupling of terminal alkynes with benzoquinones is reported. Furthermore, with naphthoquinones, owing to the cross-resonance of carbonyl with the aromatic ring, alkene-alkyne cycloaddition is more favored to give four-membered carbocyclic adducts, thereby precluding the requirement of preactivated alkynes.
- Sultan, Shaista,Bhat, Muneer-Ul-Shafi,Rizvi, Masood Ahmad,Shah, Bhahwal Ali
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p. 8948 - 8958
(2019/08/12)
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- Transition-Metal-Free Carbonylative Suzuki-Miyaura Reactions of Aryl Iodides with Arylboronic Acids Using N-Formylsaccharin as CO Surrogate
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Unprecedented, high yielding, transition-metal-free carbonylative Suzuki-Miyaura reactions of aryl iodides with arylboronic acids using N-formylsaccharin as CO surrogate have been developed. Notably, this general protocol was adapted to the synthesis of the triglyceride and cholesterol regulator drug, fenofibrate, and carbon-13 labeled biaryl ketone. (Figure presented.).
- Yu, Dezhong,Xu, Fangning,Li, Dan,Han, Wei
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supporting information
p. 3102 - 3107
(2019/05/21)
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- Synthesis of Phenols: Organophotoredox/Nickel Dual Catalytic Hydroxylation of Aryl Halides with Water
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A highly effective hydroxylation reaction of aryl halides with water under synergistic organophotoredox and nickel catalysis is reported. The OH group of the resulting phenols originates from water, following deprotonation facilitated by an intramolecular base group on the ligand. Significantly, aryl bromides as well as less reactive aryl chlorides served as effective substrates to afford phenols with a wide range of functional groups. Without the need for a strong inorganic base or an expensive noble-metal catalyst, this process can be applied to the efficient preparation of diverse phenols and enables the hydroxylation of multifunctional pharmaceutically relevant aryl halides.
- Yang, Liu,Huang, Zhiyan,Li, Gang,Zhang, Wei,Cao, Rui,Wang, Chao,Xiao, Jianliang,Xue, Dong
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supporting information
p. 1968 - 1972
(2018/02/06)
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- Practical and efficient synthesis of hydroxyaryl ketones catalyzed by HF@SiO2 under solvent-free condition
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A wide variety of hydroxyaryl ketones bearing different motifs was successfully synthesized with good yields and excellent selectivities in the presence of HF@SiO2 as an environmental friendly acid under solvent-free condition. Mild and green reaction conditions and excellent yields (50-91%) make this method an attractive method for the efficient synthesis of hydroxyaryl ketones. Fries rearrangement of phenyl benzoate in the presence of HF@SiO2 led to p-hydroxybenzophenone, while phenyl acetate in the same conditions produced o-hydroxyacetophenone as a single isomer.
- Paghandeh, Hossein,Saeidian, Hamid,Ghaffarzadeh, Mohammad
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p. 809 - 814
(2018/09/26)
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- The critical role of novel benzophenone analogs on tumor growth inhibition targeting angiogenesis and apoptosis
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In modern biology, one of the major topics of importance is progress in anti-cancer drugs with specific targets. The angiopreventive and in vitro tumor inhibition activities of novel synthetic benzophenone analogs have been investigated intensively and explored in a very systematic way. Novel benzophenone analogs (9a-d and 10a-d) substituted with methyl, chloro and fluoro groups at different positions on an identical chemical backbone and incorporating variations in the number of substituents have been synthesized in a multistep process and characterized. In this study, we further evaluate the newly synthesized compounds for their cytotoxic and anti-proliferative effects against A549, HeLa and MCF-7 cells. The potent lead compound was further assessed for anti-angiogenic effects. Through the structure-activity relationship, we found that an increase in the number of methyl, chloro and fluoro groups in a benzophenone ring on compound 9d resulted in higher potency compared to other compounds. Tumor inhibition was notably promoted, and this was reflected in effects on neovessel formation in in vivo systems, such as the CAM. Compound 9d interacts with rVEGF through hydrogen bonds in silico, thereby down-regulating the expression of VEGF in angiogenesis. From our investigation, it is suggested on the basis of clonogenesis and cell migration assays that compound 9d has the potency to exhibit prolonged activity against cancer progression, through cell cycle arrest at the G2/M phase. In addition, compound 9d inhibits A549 cells through caspase-activated DNase-mediated apoptosis.
- Mohammed, Yasser Hussein Eissa,Ara Khanum, Shaukath
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p. 639 - 656
(2018/05/03)
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- General Method for the Suzuki-Miyaura Cross-Coupling of Primary Amide-Derived Electrophiles Enabled by [Pd(NHC)(cin)Cl] at Room Temperature
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A general, highly selective method for the room temperature Suzuki-Miyaura cross-coupling of commonly encountered primary benzamides is reported. A combination of site-selective N,N-di-Boc-activation (tert-butoxycarbonyl activation) of the amide nitrogen with practical air- and moisture-stable, well-defined, and highly reactive [Pd(NHC)(cin)Cl] (NHC = N-heterocyclic carbene; cin = cinnamyl) provides a highly effective route to biaryl ketones from primary amides in high yields. For the first time, a TON of >1000 has been achieved in amide acyl cross-coupling.
- Lei, Peng,Meng, Guangrong,Ling, Yun,An, Jie,Nolan, Steven P.,Szostak, Michal
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p. 6510 - 6513
(2017/12/26)
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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 0120-0121
(2017/11/29)
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- Base free Suzuki acylation reactions of sodium (aryl trihydroxyborate) salts: A novel synthesis of substituted aryl ketones
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The first simple and efficient base free Pd(PPh3)4 catalysed synthesis of substituted aryl ketones from acyl chlorides and easily accessible sodium aryl trihydroxyborate salts in aqueous toluene is reported. The reaction conditions appeared versatile and tolerable to a variety of functional groups including, CF3, OMe, SMe, Br, NO2, F, OH and NH2 furnishing 25 examples of substituted aryl ketones in isolated yields of up to 96% in 24 h. Beside the high purity, the ease and convenience of the isolation compared to boronic acids, sodium aryl trihydroxyborate salts could be used subsequently without the addition of excess amount of an activator and are more user-friendly in terms of the use of accurate reaction stoichiometry.
- Sithebe, Siphamandla,Molefe, Patience
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p. 305 - 311
(2017/07/13)
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- Palladium-catalyzed Suzuki-Miyaura coupling of aryl esters
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The Suzuki-Miyaura coupling is among the most important C-C bond-forming reactions available due to its reliability, chemoselectivity, and diversity. Aryl halides and pseudohalides such as iodides, bromides, and triflates are traditionally used as the electrophilic coupling partner. The expansion of the reaction scope to nontraditional electrophiles is an ongoing challenge to enable an even greater number of useful products to be made from simple starting materials. Herein, we present how an NHC-based Pd catalyst can enable Suzuki-Miyaura coupling where the C(acyl)-0 bond of aryl esters takes on the role of electrophile, allowing the synthesis of various ketone-containing products. This contrasts known reactions of similar esters that provide biaryls via nickel catalysis. The underlying cause of this mechanistic divergence is investigated by DFT calculations, and the robustness of esters compared to more electrophilic acylative coupling partners is analyzed.
- Halima, Taoufik Ben,Zhang, Wanying,Yalaoui, Imane,Hong, Xin,Yang, Yun-Fang,Houk, Kendall N.,Newman, Stephen G.
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p. 1311 - 1318
(2017/05/16)
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- Visible Light Copper Photoredox-Catalyzed Aerobic Oxidative Coupling of Phenols and Terminal Alkynes: Regioselective Synthesis of Functionalized Ketones via C C Triple Bond Cleavage
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Direct oxidative coupling of phenols and terminal alkynes was achieved at room temperature by a visible-light-mediated copper-catalyzed photoredox process. This method allows regioselective synthesis of hydroxyl-functionalized aryl and alkyl ketones from simple phenols and phenylacetylene via C C triple bond cleavage. 47 examples were presented. From a synthetic perspective, this protocol offers an efficient synthetic route for the preparation of pharmaceutical drugs, such as pitofenone and fenofibrate.
- Sagadevan, Arunachalam,Charpe, Vaibhav Pramod,Ragupathi, Ayyakkannu,Hwang, Kuo Chu
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supporting information
p. 2896 - 2899
(2017/03/11)
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- Synthetic method of 4-hydroxybenzophenone
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The invention discloses a synthetic method of 4-hydroxybenzophenone, and belongs to the technical field of fine chemical engineering. The problem that an existing pressure method is incomplete in reaction and low in reaction yield is solved. The synthetic method includes the following steps that 1, 4-chlorobenzophenone, copper oxide, a phase transfer catalyst and a sodium hydroxide solution are added into a high-pressure reactor with a stirrer, stirred and heated to react for 3-8 h; 2, a material obtained after reaction is poured out of the high-pressure reactor, cooled to room temperature, diluted by adding deionized water and then filtered in a suction mode; 3, activated carbon is added into a 4-hydroxybenzophenone alkaline solution, the mixed solution is heated to boil, and suction filtration is carried out after 5-60 min to remove the activated carbon; 4, a hydrochloric acid solution with the mass concentration being 5-30% is added dropwise into the decolored 4-hydroxybenzophenone alkaline solution until the pH value of the solution is smaller than 7, and 4-hydroxybenzophenone is obtained through suction filtration and then drying. The synthetic method is used for producing 4-hydroxybenzophenone.
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Paragraph 0024; 0025; 0026; 0027; 0028; 0029
(2016/12/12)
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- Photocatalytic Hydrogen-Evolution Cross-Couplings: Benzene C-H Amination and Hydroxylation
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We present a blueprint for aromatic C-H functionalization via a combination of photocatalysis and cobalt catalysis and describe the utility of this strategy for benzene amination and hydroxylation. Without any sacrificial oxidant, we could use the dual catalyst system to produce aniline directly from benzene and ammonia, and phenol from benzene and water, both with evolution of hydrogen gas under unusually mild conditions in excellent yields and selectivities.
- Zheng, Yi-Wen,Chen, Bin,Ye, Pan,Feng, Ke,Wang, Wenguang,Meng, Qing-Yuan,Wu, Li-Zhu,Tung, Chen-Ho
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supporting information
p. 10080 - 10083
(2016/09/04)
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- Carbonylative coupling of aryl tosylates/triflates with arylboronic acids under CO atmosphere
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The carbonylative Suzuki-Miyaura reaction between aryl tosylates/triflates with arylboronic acid is herein reported, using base-free conditions and a balloon pressure of carbon monoxide. Under these conditions, unsymmetrical biaryl ketones were obtained in modest to excellent yields. This method was adapted to the synthesis of oxybenzone and ketoprofen in good yields under mild conditions.
- Hao, Cheng Yi,Wang, Dan,Li, Ya Wei,Dong, Lin Lin,Jin, Ying,Zhang, Xiu Rong,Zhu, He Yun,Chang, Sheng
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p. 86502 - 86509
(2016/09/23)
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- Synthesis and biological evaluation of negative allosteric modulators of the Kv11.1(hERG) channel
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We synthesized and evaluated a series of compounds for their allosteric modulation at the Kv11.1 (hERG) channel. Most compounds were negative allosteric modulators of [3H]dofetilide binding to the channel, in particular 7f, 7h-j and 7p. Compounds 7f and 7p were the most potent negative allosteric modulators amongst all ligands, significantly increasing the dissociation rate of dofetilide in the radioligand kinetic binding assay, while remarkably reducing the affinities of dofetilide and astemizole in a competitive displacement assay. Additionally, both 7f and 7p displayed peculiar displacement characteristics with Hill coefficients significantly distinct from unity as shown by e.g., dofetilide, further indicative of their allosteric effects on dofetilide binding. Our findings in this investigation yielded several promising negative allosteric modulators for future functional and clinical research with respect to their antiarrhythmic propensities, either alone or in combination with known Kv11.1 blockers.
- Yu, Zhiyi,Van Veldhoven, Jacobus P.D.,'T Hart, Ingrid M.E.,Kopf, Adrian H.,Heitman, Laura H.,Ijzerman, Adriaan P.
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- An eco-friendly Co(OAc)2-catalyzed aerobic oxidation of 4-benzylphenols into 4-hydroxybenzophenones
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An undecorated Co(OAc)2-catalyzed aerobic oxidation system has been reported that enables direct transformation of 4-benzylphenols into the corresponding 4-hydroxybenzophenones. The procedure is especially suitable for electron-withdrawing group-containing substrates, which are commonly inefficient to conduct this category of oxidation. Based on well-defined p-benzoquinone methides and the confirmed ethereal intermediate, a plausible mechanism was depicted.
- Huang, Jian-Gang,Guo, Ying,Jiang, Jian-An,Liu, Hong-Wei,Ji, Ya-Fei
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p. 7115 - 7124
(2015/02/19)
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- Transition-metal-free, ambient-pressure carbonylative cross-coupling reactions of aryl halides with potassium aryltrifluoroborates
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We disclose an unprecedented transition-metal-free carbonylative cross coupling of aryl halides with potassium aryl trifluoroborates even at atmospheric pressure of carbon monoxide. This protocol is efficient, operationally simple, and shows wide scope with regard to both aryl halides and potassium aryl trifluoroborates containing a series of active functional groups.
- Jin, Fengli,Han, Wei
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supporting information
p. 9133 - 9136
(2015/06/08)
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- Palladium catalyzed addition of arylboronic acid or indole to nitriles: Synthesis of aryl ketones
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Aryl ketones can be synthesized conveniently by a palladium catalyzed addition of arylboronic acid to nitriles in aqueous triflic acid. This catalytic system was extended to the addition of unprotected indoles to nitriles under a slightly modified condition to produce 3-acyl indoles in good yields.
- Das, Tuluma,Chakraborty, Amarnath,Sarkar, Amitabha
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supporting information
p. 7198 - 7202
(2015/01/09)
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- Stimuli-responsive blue fluorescent supramolecular polymers based on a pillar[5]arene tetramer
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A tetraphenylethene-bridged pillarene tetramer with aggregation-induced emission properties forms an A4/B2-type supramolecular polymer and a gel with a symmetric neutral guest linker, showing a remarkable fluorescence emission enhancement in solution and the solid state and a good responsiveness to temperature and solvent composition. This journal is the Partner Organisations 2014.
- Song, Nan,Chen, Dai-Xiong,Qiu, Yu-Chen,Yang, Xiao-Yue,Xu, Bin,Tian, Wenjing,Yang, Ying-Wei
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supporting information
p. 8231 - 8234
(2014/07/21)
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- Catalytic application of fluorous silica gel in Fries rearrangement
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Commercially available fluorous silica gel (Fluoro Flash) with no further post-modification was successfully investigated and applied merely as a catalyst in Fries rearrangement of various aryl esters under solvent free conditions in 4 h and optimized temperatures. In addition to good yields and recyclability of the catalyst, toxicity of reaction medium, by-products, and wastes were minimized. Also, low catalyst loading was another advantage of this methodology.
- Ghaffarzadeh, Mohammad,Ahmadi, Maryam
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- Silver-catalyzed decarboxylative acylation of arylglyoxylic acids with arylboronic acids
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The silver-catalyzed coupling of arylboronic acids with arylglyoxylic acids was found to be an extremely efficient route for the synthesis of unsymmetrical diaryl ketones. It can be conducted on a gram scale under mild and open-flask conditions with good functional group compatibility, avoiding the addition of expensive and/or toxic metals. This journal is
- Cheng, Kai,Zhao, Baoli,Qi, Chenze
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p. 48698 - 48702
(2014/12/10)
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- AIBN-catalyzed oxidative cleavage of gem -disubstituted alkenes with O 2 as an oxidant
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A 2,2-azobis(isobutyronitrile) (AIBN) catalyzed oxidative cleavage of gem-disubstituted alkenes with molecular oxygen as the oxidant has been described. Carbonyl compounds were obtained as the desired products in high yield under mild conditions. Based on previous documents and current experimental results, a relatively reasonable mechanism is proposed.
- Wang, Guang-Zu,Li, Xing-Long,Dai, Jian-Jun,Xu, Hua-Jian
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p. 7220 - 7225
(2014/08/18)
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- Palladium-catalyzed hydroxylation of aryl and heteroaryl halides enabled by the use of a palladacycle precatalyst
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A method for the hydroxylation of aryl and heteroaryl halides, promoted by a catalyst based on a biarylphosphine ligand tBuBrettPhos (L5) and its corresponding palladium precatalyst (1), is described. The reactions allow the cross-coupling of both potassium and cesium hydroxides with (hetero)aryl halides to afford a variety of phenols and hydroxylated heteroarenes in high to excellent yield.
- Cheung, Chi Wai,Buchwald, Stephen L.
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p. 5351 - 5358
(2014/06/23)
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- Efficient cleavage of alkyl aryl ethers using an ionic liquid under microwave irradiation
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A highly reliable dealkylation protocol of alkyl aryl ethers, whose alkyl groups are longer than methyl group, has been developed. We report that various ethyl, n-propyl, and benzyl aryl ethers are successfully cleaved using an ionic liquid, 1-n-butyl-3-methylimidazolium bromide, [bmim][Br], under microwave irradiation. Despite many characteristics such as lower cost and less toxicity of the alkylating agents, and greater hydrophobicity of the products, longer alkyl ethers have been significantly less exploited than methyl ethers, probably due to more difficulty in the deprotection step. Since it has the same advantages as the demethylation method developed by this group including mild conditions, short reaction time, and small use of the ionic liquids, the dealkylation protocol can greatly encourage the broader use of longer alkyl groups in the protection of phenolic groups. As with our previous study of demethylation using [bmim][Br], the microwave irradiation is crucial for the deprotection of longer alkyl aryl ethers. Unlike the conventional heating, which causes either low conversion or decomposition, the microwave irradiation seems to more effectively provide energy to cleave the ether bonds and therefore suppresses the undesired reactions.
- Park, Se Kyung,Battsengel, Oyunsaikhan,Chae, Junghyun
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supporting information
p. 174 - 178
(2013/08/24)
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- Pd2dba3/Bippyphos: A robust catalyst system for the hydroxylation of aryl halides with broad substrate scope
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A mixture of tris(dibenzylideneacetone)dipalladium(0) (Pd 2dba3) and 5-(di-tert-butylphosphino)-1′,3′, 5′-triphenyl-1′H-[1,4′]bipyrazole (Bippyphos) is shown to be a robust and efficient catalyst system for the hydroxylation of structurally diverse (hetero)aryl halides under mild conditions and with broad substrate scope. Included in this reactivity survey is the successful synthesis of substituted benzofurans and related heteroatomic derivatives, which are formed via the hydroxylation of 2-haloalkynylarenes. Notably, a significant number of the reactions reported herein proceed at room temperature, and we have demonstrated that it is possible to conduct reactions on the benchtop under air using unpurified solvents with negligible loss in reactivity versus related transformations conducted under inert atmosphere conditions. We also report herein the first crystallographically characterized (Bippyphos)Pd(II) complex, which confirms the ability of this synthetically useful ligand to adopt a bidentate binding motif in a manner similar to Buchwald's biarylphosphine ligand class. Copyright
- Lavery, Christopher B.,Rotta-Loria, Nicolas L.,McDonald, Robert,Stradiotto, Mark
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supporting information
p. 981 - 987
(2013/05/08)
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- Synthesis of fluorenone derivatives through Pd-catalyzed dehydrogenative cyclization
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Palladium-catalyzed dual C-H functionalization of benzophenones to form fluorenones by oxidative dehydrogenative cyclization is reported. This method provides a concise and effective route toward the synthesis of fluorenone derivatives, which shows outstanding functional group compatibility.
- Li, Hu,Zhu, Ru-Yi,Shi, Wen-Juan,He, Ke-Han,Shi, Zhang-Jie
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supporting information
p. 4850 - 4853,4
(2012/12/12)
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- Synthesis, biochemical evaluation and rationalisation of a series of 3,5- dibromo derivatives of 4-hydroxyphenyl ketone-based compounds as probes of the active site of type 3 of 17β-hydroxysteroid dehydrogenase (17β-hsd3) and the role of hydrogen bonding interaction in the inhibition of 17β-HSD3
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We report the synthesis, evaluation and rationalisation of the inhibitory activity of a series of 3,5-dibromo derivatives of 4-hydroxyphenyl ketone as probes of the active site of the type 3 of 17β-hydroxysteroid dehydrogenase (17β-HSD3). The results support the important role of hydrogen bonding interaction in the inhibition of 17β-HSD3.
- Olusanjo, Moniola S.,Mashru, Shreena N.,Cartledge, Timothy,Ahmed, Sabbir
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scheme or table
p. 604 - 610
(2012/08/28)
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- Microwave promoted Suzuki reactions between aroyl chlorides and boronic acids catalyzed by heterogeneous and homogeneous phosphine-free palladium catalysts
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Suzuki cross-coupling reactions between arylboronic acids and aroyl chlorides with phosphine-free palladium catalysis under microwave irradiation were performed to obtainment of aromatic ketones in good yields within short times. Heterogeneous and homogeneous catalysts were studied as well as their influence in the reaction selectivity relative to homocoupling of the boronic acids.
- De Luna Martins, Daniela,Aguiar, Lúcia C.S.,Antunes, Octavio A.C.
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experimental part
p. 2845 - 2849
(2011/08/10)
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- Protolytic defluorination of trifluoromethyl-substituted arenes
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A series of trifluoromethyl-substituted arenes were studied in their reactions with Bronsted superacids. The products from these reactions suggest the formation of reactive electrophiles, such as carbocations, acylium cations or equivalent electrophilic species. As such, Friedel-Crafts-type reactions occur between these species and arene nucleophiles. NMR studies were done, and the results suggest the formation of an acyl group from the trifluoromethyl groups in the superacid.
- Kethe, Anila,Tracy, Adam F.,Klumpp, Douglas A.
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experimental part
p. 4545 - 4549
(2011/07/29)
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- D-Glucose as green ligand for selective copper-catalyzed phenol synthesis from aryl halides with an easy catalyst removal
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With the growing demand of environmentally friendly reagents for organic reactions, for the first time the utility of d-glucose as a ligand in its direct form has been described using a typical example of copper-catalyzed coupling reaction for phenol synthesis with a high degree of selectivity and easy catalyst removal.
- Thakur, Krishna Gopal,Sekar, Govindasamy
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supporting information; experimental part
p. 6692 - 6694
(2011/07/09)
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- Microwave-assisted demethylation of methyl aryl ethers using an ionic liquid
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An efficient demethylation of methyl aryl ethers using an ionic liquid, 1-n-butyl-3-methylimidazolium bromide ([bmim][Br]) has been developed. Methyl aryl ethers are successfully cleaved by the halide anion of [bmim][Br], without aid of any other activating agents. In this reaction, microwave irradiation was found to be crucial for the effective conversion. The newly developed protocol is a very attractive green chemical process as it utilizes minimal amount of cleaving reagents and does not require additional activating agents or solvents. Under the conditions described herein, a broad range of methyl aryl ethers were converted to the corresponding phenolic compounds in moderate to excellent yields in a short time. Georg Thieme Verlag Stuttgart New York.
- Park, Jiyeon,Chae, Junghyun
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experimental part
p. 1651 - 1656
(2010/08/22)
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- Highly efficient and scalable process for demethylation of 6-(2,4-dimethoxybenzoyl)chromen-2-one and other aryl methyl ethers
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Demethylation of 6-(2,4-dimethoxybenzoyl)chromen-2-one and some other aryl methyl ethers was achieved with pyridinium bromide as demethylating agent and sulfolane as solvent. Compared with other demethylation methods, this combination offers advantages of clean conversion, excellent yields, easy operation and workup, and manageable reaction temperatures. This process could be particularly useful for large-scale production because it avoids use of corrosive or moisture-sensitive reagents. Copyright
- Srivastava, Amit,Yang, Jason,Zhao, Baoshu,Jiang, Yong,Blackmon, Wade,Kraemer, Bernd
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experimental part
p. 1765 - 1771
(2010/07/07)
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- Convenient Stille carbonylative cross-couplings using molybdenum hexacarbonyl
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Palladium catalysis was used in Stille-type carbonylative cross-couplings employing Mo(CO)6 as the carbon monoxide source. Robust and convenient transformations were carried out in closed vessels at 100 °C, providing a set of diaryl ketones in good yields. Aryl triflates and bromides were used as coupling partners with aryl stannanes. Inclusion of the Mo(CO)6 destabilizing agent DBU made this protocol operationally simple and suppressed side-product formation.
- Lindh, Jonas,Fardost, Ashkan,Almeida, Maria,Nilsson, Peter
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experimental part
p. 2470 - 2472
(2010/07/04)
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