- Simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid
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A simple synthesis of fresh alkyl iodides using alcohols and hydriodic acid (HI) is reported. The alkyl iodides were obtained in quick and easy work-up with good to excellent yields (66-94%) and very high purities (97-99%). Freshly prepared iodomethane and 1-iodobutane were applied to synthesize biologically relevant 3,7-dimethyladenine and 9-butyladenine, which were characterized thoroughly using 1D and 2D NMR, individually.
- Klein, Suzane M.,Zhang, Cungen,Jiang, Yu Lin
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- REACTIVITY OF t-BUTYLDIMETHYLSILYL ETHERS : A FACILE CONVERSION INTO BROMIDE
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TBDMS ether can be efficiently converted in one step into the corresponding bromides by a CBr4, PPh3 and acetone mixture.
- Mattes, Henri,Benezra, Claude
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- Kinetics of the nucleophilic substitution of benzyltributylammonium bromide with allyl, butyl, and benzyl chlorides and with benzyl acetate and benzyl ether
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In this study, we investigated the kinetics of the nucleophilic substitutions, RX + (BzBu3NBr) ? RBr + (BzBu3NX), where R = allyl, Bu and Bz, when X = Cl; and X = AcO and BzO when R = Bz. The forward and backward rate constants in addition to the activation energies for R = allyl and Bu were also determined. However, only the rate constants at 35°C were determined for the benzyl compounds with toluene as the solvent to reduce the reaction rate. Moreover, the effects of the structures of the groups R and the leaving groups X on the reactivity were compared. Results in this study can provide valuable information for future studies involving the phase transfer catalyzed displacements.
- Wang, Ten-Tsai,Chang, Chyi-Huang,Huang, Ting-Chia
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- Organic synthesis in water/carbon dioxide emulsions
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The synthetic reaction between a hydrophobe, benzyl chloride, and a hydrophilic nucleophile, KBr, is reported in water-in-carbon dioxide (w/c) and carbon dioxide-in-water (c/w) emulsions. Emulsions containing equal amounts of water and CO2 were
- Jacobson,Lee C.T.,DaRocha,Johnston
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- Kinetics of the gas-phase elimination of α-bromophenylacetic acid under maximum inhibition
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The gas phase elimination kinetics of the title compound was studied over the temperature range of 260.1-315.0 °C and pressure range of 20-70 Torr. This elimination, in seasoned static reaction system and in the presence of at least fourfold of the free r
- Chuchani, Gabriel,Dominguez, Rosa M.
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- Chlorotrimethylsilane/Lithium Bromide and Hexamethyldisilane/Pyridinium Bromide Perbromide: Effective and Selective Reagents for the Conversion of Alkyl (Cycloalkyl and Aralkyl) Alcohols into Bromides
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Alkyl bromides were obtained in high yield in the reaction of the corresponding alcohols with chlorotrimethylsilane/lithium bromide.The reaction was equally applicable to primary, secondary, and tertiary alcohols as well as to allylic and benzylic alcohols.High regioselectivity was observed in related conversions in which hexamethyldisilane/pyridinium bromide perbromide was used.Tertiary alcohols, for example, were converted selectively into the corresponding tertiary bromides in the presence of primary and secondary hydroxylic functions.The reactions were also highly steroselective.
- Olah, George A.,Gupta, B. G. Balaram,Malhotra, Ripudaman,Narang, Subhash C.
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- STEREOSPECIFIC DISPLACEMENT OF SULFUR FROM CHIRAL CENTERS. ACTIVATION VIA THIAPHOSPHONIUM SALTS.
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The first general method for direct displacement of sulfur from chiral carbon centers has been developed.Chiral mercaptans are readily converted to the corresponding thiaphosphonium salts by treatment with t-butyl hypochlorite and hexamethylphosphorous triamide.Metathesis with ammonium hexafluorophosphate provides stable, isolable, crystalline salts which undergo clean nucleophilic diplacement with a variety of heteroatom and carbon based nucleophiles, affording products in which the stereochemistry has been inverted.
- Krafft, Grant A.,Siddall, Thomas L.
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- Simple and rapid determination of the activation parameters of organic reactions by temperature-dependent NMR spectroscopy II. Application to reversible reactions
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A non-isothermal (NIT) method for evaluating the activation enthalpies and entropies of reactions in solutions was applied to several reversible reactions. This was realized by a stepwise elevation of the temperature of a reaction system using a variable-temperature apparatus comprising on NMR spectrometer and a quick collection of FID (free induction decay) at every plateau of the step. The rate from NIT experiments agreed well with the previously measured rates by the conventional methods.
- Satoh, Masahiro,Hirota, Minoru
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- Regiospecific Synthesis of Calcium-Independent Daptomycin Antibiotics using a Chemoenzymatic Method
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Daptomycin (DAP) is a calcium (Ca2+)-dependent FDA-approved antibiotic drug for the treatment of Gram-positive infections. It possesses a complex pharmacophore hampering derivatization and/or synthesis of analogues. To mimic the Ca2+-binding effect, we used a chemoenzymatic approach to modify the tryptophan (Trp) residue of DAP and synthesize kinetically characterized and structurally elucidated regiospecific Trp-modified DAP analogues. We demonstrated that the modified DAPs are several times more active than the parent molecule against antibiotic-susceptible and antibiotic-resistant Gram-positive bacteria. Strikingly, and in contrast to the parent molecule, the DAP derivatives do not rely on calcium or any additional elements for activity.
- Mupparapu, Nagaraju,Lin, Yu-Hsin Cindy,Kim, Tae Ho,Elshahawi, Sherif I.
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- Visible light induced 'on water' benzylic bromination with N-bromosuccinimide
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Benzylic bromination of various 4-substituted toluenes (Me, tert-Bu, COOEt and COMe) was effectively conducted with NBS in pure water and with a 40 W incandescent light-bulb as an initiator of the radical chain process, while electron donating groups (OMe and NHAc) directed the reaction to electrophilic aromatic substitution.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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- Association of fluorous "phase-vanishing" method with visible-light activation in benzylic bromination by bromine
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In this study the "phase-vanishing" method for diffusion-controlled addition of a reagent (Br2) to a reaction phase via a fluorous membrane (C8F18) is combined with an additional mode of activation (visible-light) to achieve the benzyl bromination of various alkyl-substituted aromatic compounds in a concentrated solution. Benzyl bromination of p-tert-butyl-toluene proceeded in various solvents including hexane and methanol, while the reaction of the neat substrate showed a similar selectivity as in carbon tetrachloride. The effect of the substituent on the para position of toluene on the course of bromination revealed three processes: benzyl bromination with H, Me, tBu and CO2Et substituents, aromatic bromination with OMe and NHAc substituents and the reaction of the 4-acetyl derivative at the substituent to form an α-bromo ketone. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Podgorsek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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- Poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide), N,N,N′,N′-tetrabromobenzene-1,3-disulfonamide and novel poly(N,N′-dibromo-N-phenylbenzene-1,3-disulfonamide) as powerful reagents for benzylic bromination
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N,N,N′,N′-Tetrabromobenzene-1,3-disulfonamide [TBBDA], poly(N,N′-dibromo-N-ethyl-benzene-1,3-disulfonamide) [PBBS], and novel poly(N,N′-dibromo-N-phenylbenzene-1,3-disulfonamide) [PBPS] can be used for bromination of benzylic positions in solvent.
- Ghorbani-Vaghei, Ramin,Chegini, Mohammad,Veisi, Hojat,Karimi-Tabar, Mehdi
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- Facile continuous process for gas phase halogen exchange over supported alkyl phosphonium salts
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Chloride-bromide halogen exchange was realized when a mixture of an alkyl chloride and an alkyl bromide were reacted over a supported molten alkyl phosphonium catalyst. Conversion was found to be near equilibrium in a tubular flow reactor at 150 °C and 1500 GHSV. The catalyst was prepared by impregnation of alumina or silica support and found to be highly stable for relatively long periods of time. A pathway for the catalytic cycle is proposed.
- Sharma, Priti,Sasson, Yoel
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- Efficient dehydrative alkylation of thiols with alcohols catalyzed by alkyl halides
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Alcohols can be efficiently converted into the useful thioethers by a transition metal- and base-free dehydrative S-alkylation reaction with thiols or disulfides by employing alkyl halides as the effective catalyst. This simple and efficient method is a green and practical way for the preparation of thioethers, as it tolerates a wide range of substrates such as aryl and alkyl thiols, as well as benzylic, allylic, secondary, tertiary, and even the less reactive aliphatic alcohols.
- Yang, Yaqi,Ye, Zihang,Zhang, Xu,Zhou, Yipeng,Ma, Xiantao,Cao, Hongen,Li, Huan,Yu, Lei,Xu, Qing
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- A facile conversion of thiols to alkyl halides by triphenylphosphine/N-halosuccinimides
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Thiols are efficiently converted to alkyl halides in high to excellent yields when treated with triphenylphosphin/N-halosuccinimide (halogen: Br,Cl, and I) in dichloromethane at room temperature.
- Iranpoor,Firouzabadi,Aghapour
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- Quadraphasic phase-vanishing method: Application to bromination reactions that produce acidic by-products
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A quadraphasic phase-vanishing method was developed that employs water as the fourth phase acting as an 'acid scavanger phase'. This protocol worked well for bromination of acetophenones giving high yields of the corresponding α-bromo ketones. Georg Thieme Verlag Stuttgart.
- Rahman, Md. Taifur,Kamata, Naoya,Matsubara, Hiroshi,Ryu, Ilhyong
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- Pure branch effect on the optical properties of novel conjugated derivatives
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Pure cooperative branch effects on one- and two-photon optical properties of conjugated derivatives are presented. AMI calculations demonstrate that the electron density distribution of the frontier orbital and the dipole moment changes of the derivatives are related to the number of branches. The theoretical results show that not only the energy level of the frontier orbital could be mediated by the number of branches, but the HOMOLUMO gap could be regulated.
- Yang, Long,Gao, Fang,Liu, Jian,Zhong, Xiaolin,Li, Hongru,Zhang, Shengtao
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- Graphite-catalyzed acylative cleavage of ethers with acyl halides
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Graphite is found to catalyze acylative cleavage of ethers such as benzylic, allylic, tert-butylic and cyclic ethers with acyl halides to give the corresponding esters in good to excellent yields. Benzylic ether was cleaved chemoselectively, when a variety of other functional groups was present, to produce the corresponding ester along with benzyl halide.
- Suzuki, Yoshitada,Matsushima, Masayuki,Kodomari, Mitsuo
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- Direct halogenation of alcohols and their derivatives with tert-Butyl halides in the ionic liquid [pmIm]Br under sonication conditions - A novel, efficient and green methodology
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A novel halogenating reagent system for direct halogenation of alcohols has been developed. tert-Butyl bromide, chloride and iodide in combination with the ionic liquid [pmIm]Br have been found to convert alcohols into the corresponding bromides, chlorides and iodides under sonication conditions (or heating) in good yields. Although a variety of primary and secondary alcohols participated in this reaction without any difficulty, tertiary alcohols remained inert. Several alcohol derivatives such as OTMS, OTBDMS, OAc, OTS and OTHP are also transformed into the corresponding halides in one-pot fashion by this procedure. A plausible rationale for this transformation is also presented. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005.
- Ranu, Brindaban C.,Jana, Ranjan
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- Nickel-Catalyzed Benzylation of C?H Bonds in Aromatic Amides with Benzyltrimethylammonium Halides
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Nickel-catalyzed benzylation reactions of C?H bonds in aromatic amides with benzyltrimethylammonium halides are developed by using a 5-chloro-8-aminoquinoline derivative as a bidentate directing group. Benzylation occurs selectively at the ortho-C?H bonds in aromatic amides, and no methylation was detected. The presence of a 5-chloro-8-aminoquinoline moiety is essential for the success of this reaction, in which a variety of functional groups can be tolerated.
- Sasagawa, Akane,Yamaguchi, Mao,Ano, Yusuke,Chatani, Naoto
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- Tribromoisocyanuric acid/triphenylphosphine: A new system for conversion of alcohols into alkyl bromides
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An efficient and facile method has been developed for the conversion of alcohols into alkyl bromides under neutral conditions using tribromoisocyanuric acid and triphenylphosphine (molar ratio 1.0:0.7:2.0, alcohol/ tribromoisocyanuric acid/triphenylphosphine) in dichloromethane at room temperature. This method can be applied for the conversion of primary, secondary, benzylic and allylic alcohols, and their corresponding bromides are obtained in 67-82 percent yield. Tertiary alcohols do not react under these conditions.
- De Andrade, Vitor S.C.,De Mattos, Marcio C.S.
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- Inorganic Micelles (Hydrophilic Core@Amphiprotic Shell) for Multiple Applications
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A facile approach for synthesizing superhydrophobic hollow silica micelles (SHSMs) with hydrophilic cores and amphiprotic (superhydrophobic/hydrophilic) shell structures that act as "all-in-one" smart nanomaterials is presented. The particles possess hydr
- Islam, Md. Shahinul,Choi, Won San,Kim, Sun Ha,Han, Oc Hee,Lee, Ha-Jin
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- Direct bromination of hydrocarbons catalyzed by Li2MnO 3 under oxygen and photo-irradiation conditions
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A method for the direct bromination of hydrocarbons with Br2 using a ubiquitous and inexpensive catalyst is highly desirable. Herein, we report the selective mono-bromination of hydrocarbons in good yield using Li2MnO3 as a catalyst under irradiation with a fluorescent room light. This new catalyst can be recycled. The effect of light was investigated using action spectra, which revealed that the reaction occurred on the surface of the catalyst.
- Nishina, Yuta,Morita, Junya,Ohtani, Bunsho
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- REACTIONS IN MICROEMULSION MEDIA. NUCLEOPHILIC DISPLACEMENT REACTION OF BENZYL CHLORIDE WITH BROMIDE ION
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A kinetic and synthetic study of the reaction of benzyl chloride with bromide ion has been performed in microemulsions composed of cetyltrimethylammonium bromide, 1-butanol, water, potassium bromide, and hexane; rates and yields of benzyl bromide formatio
- Martin, Craig A.,McCrann, Patrick M.,Angelos, George H.,Jaeger, David A.
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- A Simple Method for the Conversions of Adamantyl, Benzyl and Benzhydryl Alcohols to Their Corresponding Bromides and Chlorides and the Transhalogenation of Adamantyl, Benzyl, Benzhydryl and tertiary Alkyl Bromides and Chlorides
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Adamantyl, benzyl, and benzhydryl alcohols have been converted to their corresponding bromides and chlorides in the absence of a solvent, rapidly and in high yield using boron tribromide and tin(IV) chloride, respectively.Additionally the above bromides and chlorides can be interconverted by a transhalogenation process using the same reagents in the absence of solvent.
- Amrollah-Madjdabadi, A.,Pham, Tung N.,Ashby, E. C.
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- SYNTHESIS OF BENZYL HALIDES FROM ALDEHYDES PROMOTED BY HALOSILANES AND 1,1,3,3-TETRAMETHYLDISILOXANE (TMDS).
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Direct synthesis of monoalkyl halides from aldehydes by a new reductive halogenation method is briefly described.
- Aizpurua, Jesus M.,Palomo, Claudio
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- A simple and efficient iodination of alcohols on polymer-supported triphenylphosphine
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A simple, mild, and high-yielding procedure for the iodination of allylic, benzylic, and other primary alcohols using a combination of iodine and imidazole on polymer-supported triphenyl phosphine is described.
- Anilkumar, Gopinathan,Nambu, Hisanori,Kita, Yasuyuki
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- Highly Reactive Manganese(IV)-Oxo Porphyrins Showing Temperature-Dependent Reversed Electronic Effect in C-H Bond Activation Reactions
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We report that Mn(IV)-oxo porphyrin complexes, MnIV(O)(TMP) (1) and MnIV(O)(TDCPP) (2), are capable of activating the C-H bonds of hydrocarbons, including unactivated alkanes such as cyclohexane, via an oxygen non-rebound mechanism. Interestingly, 1 with an electron-rich porphyrin is more reactive than 2 with an electron-deficient porphyrin at a high temperature (e.g., 0 °C). However, at a low temperature (e.g., -40 °C), the reactivity of 1 and 2 is reversed, showing that 2 is more reactive than 1. To the best of our knowledge, the present study reports the first example of highly reactive Mn(IV)-oxo porphyrins and their temperature-dependent reactivity in C-H bond activation reactions.
- Guo, Mian,Seo, Mi Sook,Lee, Yong-Min,Fukuzumi, Shunichi,Nam, Wonwoo
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- Ionic liquid promoted regioselective monobromination of aromatic substrates with N-bromosuccinimide
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Aromatic substrates were monobrominated regioselectively with NBS in the ionic liquid 1,3-di-n-butylimidazolium tetrafluoroborate [bbim]BF4 in 5 min at 28°C in excellent isolated yields (80-98%) in the absence of a catalyst.
- Rajagopal,Jarikote,Lahoti,Daniel, Thomas,Srinivasan
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- Mild Aliphatic and Benzylic Hydrocarbon C-H Bond Chlorination Using Trichloroisocyanuric Acid
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We present the controlled monochlorination of aliphatic and benzylic hydrocarbons with only 1 equiv of substrate at 25-30 °C using N-hydroxyphthalimide (NHPI) as radical initiator and commercially available trichloroisocyanuric acid (TCCA) as the chlorine source. Catalytic amounts of CBr4 reduced the reaction times considerably due to the formation of chain-carrying ·CBr3 radicals. Benzylic C-H chlorination affords moderate to good yields for arenes carrying electron-withdrawing (50-85%) or weakly electron-donating groups (31-73%); cyclic aliphatic substrates provide low yields (24-38%). The products could be synthesized on a gram scale followed by simple purification via distillation. We report the first direct side-chain chlorination of 3-methylbenzoate affording methyl 3-(chloromethyl)benzoate, which is an important building block for the synthesis of vasodilator taprostene.
- Combe, Sascha H.,Hosseini, Abolfazl,Parra, Alejandro,Schreiner, Peter R.
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- Synthesis and application of new phenyl-functionalized zeolites as protection against radical bromination at the benzylic position
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New zeolites functionalized with phenyl group have been synthesized from phenyltriethoxysilane and/or tetraethylorthosilicate with dodecylamine as a template at room temperature. These zeolites have proved to have an ability to protect the benzylic position against radical bromination. 4-Chloromethylstyrene was brominated at the double bond selectively and the benzylic position was intact under irradiation with visible light in the presence of phenyl-functionalized zeolites, although without the zeolite, the both sites were brominated.
- Itoh, Akichika,Masaki, Yukio
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- THE CINE O-ALKYLATION OF OXIRANYLCARBINOLS
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The reaction of the alkoxides derived from some oxyranylcarbinols with alkyl halides occurs by electrophilic attack on the oxiranyl oxygen rather than the alkoxide one leading to formation of the rearranged oxiranylcarbinyl ether.
- Bird, C. W.,Hormozi, N.
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- BORON TRIFLUORIDE ETHERATE/HALIDE ION, A NOVEL REAGENT FOR THE CONVERSION OF ALLYL, BENZYL AND TERTIARY ALCOHOLS TO THE HALIDES
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A combination of boron trifluoride etherate and halide ion is found to be an excellent reagent for the conversion of allyl, benzyl and tertiary alcohols to the halides.
- Mandal, Arun K.,Mahajan, S. W.
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- The complex synergy of water in the metal/bromide autoxidation of hydrocarbons caused by benzylic bromide formation
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One of the most active and selective catalysts in homogeneous liquid phase oxidation using molecular oxygen (O2) is a mixture of cobalt, manganese and bromide salts in acetic acid. It has been used to produce hundreds of different carboxylic acids in high yield and purity including the commercial production of terephthalic acid from p-xylene. Water is normally a by-product in these reactions and it is shown here that its concentration is an important reaction variable. In anhydrous acetic acid, with reagents with sufficiently strong electron-withdrawing substitutents (toluene, 4-carboxytoluene, 4-chlorotoluene), all of the active bromide becomes inactive via benzylic bromide formation. The Co/Mn/ Br catalyst is therefore converted to a Co/Mn catalyst which is dubbed 'catalyst failure' because of its undesirable characteristics of lower activity, decreased selectivity especially towards over-oxidation and color formation. For 4-chlorotoluene, increasing the water concentration to 5 weight % initially decreases the rate of reaction but eventually is more active and selective because the oxidation and hydrolysis of the benzylic bromide allows for sufficient active catalytic bromide. It is shown that benzylic bromides do not 'promote' the reaction and that both oxidation and solvolysis of the benzylic bromide occurs during autoxidation. During polymethylbenzene oxidation, benzylic bromide formation occurs only with the most reactive methyl group. The complex factors during metal/bromide autoxidation -some favored by increased water concentration and others detrimental - are outlined.
- Partenheimer, Walt
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- A new synthesis and application of N, N'-dibromo-N, N'-1,2-ethylene bis(2,5-dimethyl benzene sulfonamide); as a novel selective bromination agent for aromatic compounds
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Reaction Between Novel Compound; N, N' dibromo-N, N'-1,2- ethylene bis(2,5- dimethyl benzene sulfonamide) and aromatic compounds in the carbontetrachloride produces bromo aromatic compounds. In the case of benzene rings that contain mono activated substituted, only para - bromo isomer was formed. At the presence of benzoyl peroxide in the reaction mixture α - Hydrogen from alkyl side chain was substituted with bromine.
- Ardeshir, Khazaei,Abbas, Shirdarreh
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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
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- A new synthetic approach to novel spiro-β-lactams
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An operationally simple and efficient approach for the synthesis of novel spiro-β-lactams is described. The key reaction is a halogen-mediated intrasulfenyl cyclization of a cis-3-benzylthio-3-(prop-2-ynyloxy/-enyloxy)- β-lactam procured through a Lewis acid-mediated C-3-alkylation of the trans-3-benzylthio-3-chloro-β-lactam carbocation equivalent. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
- Bhalla, Aman,Venugopalan, Paloth,Bari, Shamsher S.
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- Increasing the selectivity of bromination of aromatic compounds using Br2/SiO2
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Br2/SiO2 possessed considerable practical advantages over traditional reagents for the bromination of aromatic hydrocarbons, e.g., toluene, o-, m-, and p-xylene, anthracene and phenol. In the presence of SiO2, toluene reacted with bromine instantly. Compounds containing electron-donating substituents showed mainly bromination on the rings. The behavior of o-, m-, and p-xylene showed predominant substitution on the rings. The bromination of phenol to p-bromophenol showed good yield at 81%. Naphthalene was monobrominated to 1-bromonaphthalene with a yield of 84% in 2 has the potential to alter reaction selectivity. It may be able to switch a mechanism from radical to polar, or to influence the regioselectivity of the products formed. In the absence of SiO2, selectivity was lost and a mixture of products by substitution of bromine atom on the ring and on the side chain without any preferability was obtained. The nature of silica gel was important for the success of the reaction. Optimal results were obtained with silica gel dried at 250°C for 1 hr.
- Ghiaci,Asghari
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- NHC-palladium-catalyzed ionic liquid-accelerated regioselective oxyarylation of alkynes with diaryl ethers?
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The first NHC-palladium-catalyzed regioselective oxyarylation of oxime ether in a task-specific ionic liquid via C(sp3)-O and C(sp2)-O bond cleavage of two different types of ethers for the assembly of structurally diverse 4-arylisoxazoles is described. Both the basic ionic liquid [C3NH2mim]Br and NHC-Pd catalyst IPr-Pd-Im-Cl2 played an important role in this transformation. Notably, this new approach provides a practical and straightforward route to access a broad range of privileged 4-arylisoxazole structures with good yields and excellent regioselectivities. Significantly, this catalytic system can be recycled up to eight times without significant loss of catalytic activity.
- Cen, Liying,He, Dan,Jiang, Huanfeng,Li, Jianxiao,Lin, Zidong,Wu, Wanqing
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supporting information
p. 1983 - 1988
(2022/04/03)
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- Synthesis, Docking, and Biological activities of novel Metacetamol embedded [1,2,3]-triazole derivatives
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ERα controls the breast tissue development and progression of breast cancer. In our search for novel compounds to target Estrogen Receptor Alpha Ligand-Binding Domain, we identified “N-(3-((1H-1,2,3-triazol-4-yl)methoxy)phenyl)acetamide” derivatives as lead compounds. The Docking studies indicated good docking score for Metacetamol derivatives when docked into the 1XP6. A series of metacetamol derivatives have been synthesized, characterized and evaluated for cytotoxicity, anti bacterial and anti oxidant activities. Among the tested twelve hybrid compounds, “7a, 7g, 7h and 7i” derivatives showed promising cytotoxicity with IC50 value of 50 value of 30 μM, whereas Compounds “7a, 7b, 7c, 7d, 7g, 7j, 7k and 7l” showed moderate anti bacterial activity with the MIC value of 300 μM.
- Battu, Satyanarayana,Joolakanti, Hima Bindhu,Kamepalli, Ramanjaneyulu,Miryala, Jeevanreddy
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- [1,3]-Claisen rearrangement via removable functional group mediated radical stabilization
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A thermal O-to-C [1,3]-rearrangement of α-hydroxy acid derived enol ethers was achieved under mild conditions. The 2-aminothiophenol protection of carboxylic acids facilitates formation of the [1,3] precursor and its thermal rearrangement via stabilization of a radical intermediate. Experimental and theoretical evidence for dissociative radical pair formation, its captodative stability via aminothiophenol, and a unique solvent effect are presented. The aminothiophenol was deprotected from rearrangement products as well as after derivatization to useful synthons.
- Alam, Md Nirshad,Dash, Soumya Ranjan,Mukherjee, Anirban,Pandole, Satish,Marelli, Udaya Kiran,Vanka, Kumar,Maity, Pradip
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supporting information
p. 890 - 895
(2021/02/01)
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- One-Step Synthesis of Triphenylphosphonium Salts from (Het)arylmethyl Alcohols
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Two approaches for the synthesis of substituted phosphonium salts from easily available benzyl alcohols and their heterocyclic analogs have been developed. The developed protocols are complementary: the direct mixing of alcohol, trimethylsilyl bromide, and triphenylphosphine in 1,4-dioxane followed by heating at 80 °C was found to be more efficient for acid-sensitive substrates, such as salicyl or furfuryl alcohols as well as secondary benzyl alcohols, while a one-pot procedure including sequential addition of trimethylsilyl bromide and triphenylphosphine gave higher yields for benzyl alcohols bearing electroneutral or electron-withdrawing substituents.
- Abaev, Vladimir T.,Chalikidi, Petrakis N.,Demidov, Oleg P.,Gutnov, Andrey V.,Magkoev, Taimuraz T.,Trushkov, Igor V.,Uchuskin, Maxim G.
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p. 9838 - 9846
(2021/07/28)
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- Induced Fitting and Polarization of a Bromine Molecule in an Electrophilic Inorganic Molecular Cavity and Its Bromination Reactivity
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Dodecavanadate, [V12O32]4? (V12), possesses a 4.4 ? cavity entrance, and the cavity shows unique electrophilicity. Owing to the high polarizability, Br2 was inserted into V12, inducing the inversion of one of the VO5 square pyramids to form [V12O32(Br2)]4? (V12(Br2)). The inserted Br2 molecule was polarized and showed a peak at 185 cm?1 in the IR spectrum. The reaction of V12(Br2) and toluene yielded bromination of toluene at the ring, showing the electrophilicity of the inserted Br2 molecule. Compound V12(Br2) also reacted with propane, n-butane, and n-pentane to give brominated alkanes. Bromination with V12(Br2) showed high selectivity for 3-bromopentane (64 %) among the monobromopentane products and preferred threo isomer among 2-,3-dibromobutane and 2,3-dibromopenane. The unique inorganic cavity traps Br2 leading the polarization of the diatomic molecule. Owing to its new reaction field, the trapped Br2 shows selective functionalization of alkanes.
- Hayashi, Yoshihito,Inada, Yasuhiro,Katayama, Misaki,Kikukawa, Yuji,Kitajima, Hiromasa,Seto, Kensuke,Watanabe, Daiki,Yamashita, Shohei
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supporting information
p. 14399 - 14403
(2020/07/13)
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- Design and synthesis of substituted (1-(benzyl)-1: H -1,2,3-triazol-4-yl)(piperazin-1-yl)methanone conjugates: Study on their apoptosis inducing ability and tubulin polymerization inhibition
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A library of substituted (1-(benzyl)-1H-1,2,3-triazol-4-yl)(piperazin-1-yl)methanone derivatives were designed, synthesized and screened for their in vitro cytotoxic activity against BT-474, HeLa, MCF-7, NCI-H460 and HaCaT cells by employing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among all the synthesized analogues, compound 10ec displayed the highest cytotoxicity with the IC50 value of 0.99 ± 0.01 μM towards BT-474 cancer cell line. The target compound (10ec) was also evaluated for its tubulin polymerization inhibition study. Detailed biological studies such as acridine orange/ethidium bromide (AO/EB), DAPI and annexin V-FITC/propidium iodide staining assay suggested that compound 10ec induced the apoptosis of BT-474 cells. The clonogenic assay revealed that the inhibition of colony formation in BT-474 cells by 10ec in concentration-dependent manner. Moreover, the flow cytometric analysis revealed that 10ec induced apoptosis via cell cycle arrest at the sub-G1 and G2/M phase. In silico studies of sulfonyl piperazine-integrated triazole conjugates unveil that they possess drug-like properties. According to the molecular modelling studies, compound 10ec binds to the colchicine binding site of the tubulin.
- Alvala, Mallika,Babu, Bathini Nagendra,Devi, Ganthala Parimala,Godugu, Chandraiah,Manasa, Kesari Lakshmi,Nagesh, Narayana,Sigalapalli, Dilep Kumar,Thatikonda, Sowjanya,Vuppaladadium, Sowmya
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supporting information
p. 1295 - 1302
(2020/12/01)
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- Thiourea-Mediated Halogenation of Alcohols
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The halogenation of alcohols under mild conditions expedited by the presence of substoichiometric amounts of thiourea additives is presented. The amount of thiourea added dictates the pathway of the reaction, which may diverge from the desired halogenation reaction toward oxidation of the alcohol, in the absence of thiourea, or toward starting material recovery when excess thiourea is used. Both bromination and chlorination were highly efficient for primary, secondary, tertiary, and benzyl alcohols and tolerate a broad range of functional groups. Detailed electron paramagnetic resonance (EPR) studies, isotopic labeling, and other control experiments suggest a radical-based mechanism. The fact that the reaction is carried out at ambient conditions, uses ubiquitous and inexpensive reagents, boasts a wide scope, and can be made highly atom economic, makes this new methodology a very appealing option for this archetypical organic reaction.
- Mohite, Amar R.,Phatake, Ravindra S.,Dubey, Pooja,Agbaria, Mohamed,Shames, Alexander I.,Lemcoff, N. Gabriel,Reany, Ofer
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p. 12901 - 12911
(2020/11/26)
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- N -Hydroxyphthalimide/benzoquinone-catalyzed chlorination of hydrocarbon C-H bond using N -chlorosuccinimide
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The direct chlorination of C-H bonds has received considerable attention in recent years. In this work, a metal-free protocol for hydrocarbon C-H bond chlorination with commercially available N-chlorosuccinimide (NCS) catalyzed by N-hydroxyphthalimide (NHPI) with 2,3-dicyano-5,6-dichlorobenzoquinone (DDQ) functioning as an external radical initiator is presented. Aliphatic and benzylic substituents and also heteroaromatic ones were found to be well tolerated. Both the experiments and theoretical analysis indicate that the reaction goes through a process wherein NHPI functions as a catalyst rather than as an initiator. On the other hand, the hydrogen abstraction of the C-H bond conducted by a PINO species rather than the highly reactive N-centered radicals rationalizes the high chemoselectivity of the monochlorination obtained by this protocol as the latter is reactive towards the C(sp3)-H bonds of the monochlorides. The present results could hold promise for further development of a nitroxy-radical system for the highly selective functionalization of the aliphatic and benzylic hydrocarbon C-H.
- Li, Zi-Hao,Fiser, Béla,Jiang, Biao-Lin,Li, Jian-Wei,Xu, Bao-Hua,Zhang, Suo-Jiang
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supporting information
p. 3403 - 3408
(2019/04/01)
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- Photochemical benzylic bromination in continuous flow using BrCCl3 and its application to telescoped p-methoxybenzyl protection
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BrCCl3 represents a rarely used benzylic brominating reagent with complementary reactivity to other reagents. Its reactivity has been revisited in continuous flow, revealing compatibility with electron-rich aromatic substrates. This has brought about the development of a p-methoxybenzyl bromide generator for PMB protection, which was successfully demonstrated on a pharmaceutically relevant intermediate on 11 g scale, giving 91% yield and a PMB-Br space-time-yield of 1.27 kg L?1 h?1
- Otake, Yuma,Williams, Jason D.,Rincón, Juan A.,De Frutos, Oscar,Mateos, Carlos,Kappe, C. Oliver
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supporting information
p. 1384 - 1388
(2019/02/14)
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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
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p. 6184 - 6198
(2019/05/08)
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- Anti-oligomerization sheet molecules: Design, synthesis and evaluation of inhibitory activities against α-synuclein aggregation
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Aggregation of α-synuclein (α-Syn) play a key role in the development of Parkinson Disease (PD). One of the effective approaches is to stabilize the native, monomeric protein with suitable molecule ligands. We have designed and synthesized a series of sheet-like conjugated compounds which possess different skeletons and various heteroatoms in the two blocks located at both ends of linker, which have good π-electron delocalization and high ability of hydrogen-bond formation. They have shown anti-aggregation activities in vitro towards α-Syn with IC50 down to 1.09 μM. The molecule is found binding in parallel to the NACore within NAC domain of α-Syn, interfering aggregation of NAC region within different α-Syn monomer, and further inhibiting or slowing down the formation of α-Syn oligomer nuclei at lag phase. The potential inhibitor obtained by our strategy is considered to be highly efficient to inhibit α-Syn aggregation.
- Liu, Hao,Chen, Li,Zhou, Fei,Zhang, Yun-Xiao,Xu, Ji,Xu, Meng,Bai, Su-Ping
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supporting information
p. 3089 - 3096
(2019/06/14)
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- 1,2-Dibromotetrachloroethane: An efficient reagent for many transformations by modified Appel reaction
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An efficient and facile method has been developed for the synthesis of alkyl bromides from various alcohols under mild conditions using a triphenylphosphine (PPh 3) /1,2-dibromotetrachloroethane (DBTCE) complex in excellent yields and very short time (5 min). This method can also be applied for the transformation of chiral alcohols to their corresponding bromides in very high enantiomeric excess. The PPh 3 /DBTCE complex is also successfully applied to ring-opening reactions of cyclic ethers in mild conditions. Esterification, amidation, and formation of acid anhydrides under very mild experimental conditions are also successfully accomplished by following a modification of the Appel reaction protocol in this work.
- Essiz, Sel?uk,Da?tan, Arif
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p. 150 - 156
(2019/05/16)
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- Promotion of Appel-type reactions by N-heterocyclic carbenes
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N-Heterocyclic carbenes (NHCs) have been extensively used as a versatile class of catalysts and ligands in organocatalytic and organometallic chemistry. However, there are only a small number of synthetic applications where they act as reagents. Here we demonstrate that NHCs can be used as stoichiometric redox reagents for Appel-type halogenation reactions of alcohols. This new reactivity reveals a fresh and interesting aspect and enriches the chemistry of NHCs in an underexplored area. The potential of performing this chemical transformation at the catalytic level using an NHC-oxide derivative is also investigated.
- Hussein, Mohanad A.,Nguyen, Thanh Vinh
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supporting information
p. 7962 - 7965
(2019/07/12)
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- Synthesis and biological evaluation of 1-benzyl-N-(2-(phenylamino)pyridin-3-yl)-1H-1,2,3-triazole-4-carboxamides as antimitotic agents
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A library of 1-benzyl-N-(2-(phenylamino)pyridin-3-yl)-1H-1,2,3-triazole-4-carboxamides (7a–al) have been designed, synthesized and screened for their anti-proliferative activity against some selected human cancer cell lines namely DU-145, A-549, MCF-7 and HeLa. Most of them have shown promising cytotoxicity against lung cancer cell line (A549), amongst them 7f was found to be the most potent anti-proliferative congener. Furthermore, 7f exhibited comparable tubulin polymerization inhibition (IC50 value 2.04 μM) to the standard E7010 (IC50 value 2.15 μM). Moreover, flow cytometric analysis revealed that this compound induced apoptosis via cell cycle arrest at G2/M phase in A549 cells. Induction of apoptosis was further observed by examining the mitochondrial membrane potential and was also confirmed by Hoechst staining as well as Annexin V-FITC assays. Furthermore, molecular docking studies indicated that compound 7f binds to the colchicine binding site of the β-tubulin. Thus, 7f exhibits anti-proliferative properties by inhibiting the tubulin polymerization through the binding at the colchicine active site and by induction of apoptosis.
- Prasad, Budaganaboyina,Lakshma Nayak,Srikanth,Baig, Mirza Feroz,Subba Reddy,Babu, Korrapati Suresh,Kamal, Ahmed
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p. 535 - 548
(2018/11/26)
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- Developing glutathione-activated catechol-type diphenylpolyenes as small molecule-based and mitochondria-targeted prooxidative anticancer theranostic prodrugs
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Developing concise theranostic prodrugs is highly desirable for personalized and precision cancer therapy. Herein we used the glutathione (GSH)-mediated conversion of 2,4-dinitrobenzenesulfonates to phenols to protect a catechol moiety and developed stable pro-catechol-type diphenylpolyenes as small molecule-based prooxidative anticancer theranostic prodrugs. These molecules were synthesized via a modular route allowing creation of various pro-catechol-type diphenylpolyenes. As a typical representative, PDHH demonstrated three unique advantages: (1) capable of exploiting increased levels of GSH in cancer cells to in situ release a catechol moiety followed by its in situ oxidation to o-quinone, leading to preferential redox imbalance (including generation of H2O2 and depletion of GSH) and final selective killing of cancer cells over normal cells, and is also superior to 5-fluorouracil and doxorubicin, the widely used chemotherapy drugs, in terms of its ability to kill preferentially human colon cancer SW620 cells (IC50 = 4.3 μM) over human normal liver L02 cells (IC50 = 42.3 μM) with a favourable in vitro selectivity index of 9.8; (2) permitting a turn-on fluorescent monitoring for its release, targeting mitochondria and therapeutic efficacy without the need of introducing additional fluorophores after its activation by GSH in cancer cells; (3) efficiently targeting mitochondria without the need of introducing additional mitochondria-directed groups.
- Bao, Xia-Zhen,Dai, Fang,Wang, Qi,Jin, Xiao-Ling,Zhou, Bo
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p. 406 - 418
(2019/02/06)
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- Sodium Sulfite-Involved Photocatalytic Radical Cascade Cyclization of 2-Isocyanoaryl Thioethers: Access to 2-CF2/CF3-Containing Benzothiazoles
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A visible-light-induced radical cascade cyclization of 2-isocyanoaryl thioethers for the synthesis of 2-CF2/CF3-containing benzothiazoles has been developed. Sodium sulfite can participate in the photocatalytic cycle as a reductant that efficiently transforms Ir4+ into Ir3+ to promote the fluoroalkylation under mild reaction conditions.
- Yuan, Yao,Dong, Wuheng,Gao, Xiaoshuang,Xie, Xiaomin,Zhang, Zhaoguo
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supporting information
p. 469 - 472
(2019/01/11)
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- Synthesis of Alkyl Halides from Aldehydes via Deformylative Halogenation
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An unprecedented deformylative halogenation of aldehydes to alkyl halides is presented. Under oxidative conditions, 1,4-dihydropyridine (DHP), derived from an aldehyde, generated a C(sp3)- radical that coupled with a halogen radical that was generated from inexpensive and atom-economical halogen sources (NaBr, NaI, or HCl), to yield an alkyl halide. Because of the mild conditions, a wide range of functional groups were tolerated, and excellent site selectivity was achieved.
- Liang, Shengzong,Kumon, Tatsuya,Angnes, Ricardo A.,Sanchez, Melissa,Xu, Bo,Hammond, Gerald B.
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supporting information
p. 3848 - 3854
(2019/05/24)
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- Alkyl Halides via Visible Light Mediated Dehalogenation
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Net selective bromination and chlorination of activated C-H bonds can be effected in generally high yield via a simple perhalogenation/dehalogenation sequence. The photochemical reductions require no photocatalyst, relying instead on the formation of an electron donor-acceptor complex of the substrate and reductant, or alternatively autophotocatalysis. Some reactions proceed despite any apparent photon absorption, serving as a cautionary tale for other photochemical reactions involving amines. Mechanistic experiments provide an explanation for this observation.
- Rathnayake, Manjula D.,Weaver, Jimmie D.
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supporting information
p. 9681 - 9687
(2019/11/28)
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- Selective C-H halogenation over hydroxylation by non-heme iron(iv)-oxo
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Non-heme iron based halogenase enzymes promote selective halogenation of the sp3-C-H bond through iron(iv)-oxo-halide active species. During halogenation, competitive hydroxylation can be prevented completely in enzymatic systems. However, synthetic iron(iv)-oxo-halide intermediates often result in a mixture of halogenation and hydroxylation products. In this report, we have developed a new synthetic strategy by employing non-heme iron based complexes for selective sp3-C-H halogenation by overriding hydroxylation. A room temperature stable, iron(iv)-oxo complex, [Fe(2PyN2Q)(O)]2+ was directed for hydrogen atom abstraction (HAA) from aliphatic substrates and the iron(ii)-halide [FeII(2PyN2Q)(X)]+ (X, halogen) was exploited in conjunction to deliver the halogen atom to the ensuing carbon centered radical. Despite iron(iv)-oxo being an effective promoter of hydroxylation of aliphatic substrates, the perfect interplay of HAA and halogen atom transfer in this work leads to the halogenation product selectively by diverting the hydroxylation pathway. Experimental studies outline the mechanistic details of the iron(iv)-oxo mediated halogenation reactions. A kinetic isotope study between PhCH3 and C6D5CD3 showed a value of 13.5 that supports the initial HAA step as the RDS during halogenation. Successful implementation of this new strategy led to the establishment of a functional mimic of non-heme halogenase enzymes with an excellent selectivity for halogenation over hydroxylation. Detailed theoretical studies based on density functional methods reveal how the small difference in the ligand design leads to a large difference in the electronic structure of the [Fe(2PyN2Q)(O)]2+ species. Both experimental and computational studies suggest that the halide rebound process of the cage escaped radical with iron(iii)-halide is energetically favorable compared to iron(iii)-hydroxide and it brings in selective formation of halogenation products over hydroxylation.
- Rana, Sujoy,Biswas, Jyoti Prasad,Sen, Asmita,Clémancey, Martin,Blondin, Geneviève,Latour, Jean-Marc,Rajaraman, Gopalan,Maiti, Debabrata
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p. 7843 - 7858
(2018/10/31)
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- Highly selective halogenation of unactivated C(sp3)-H with NaX under co-catalysis of visible light and Ag@AgX
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The direct selective halogenation of unactivated C(sp3)-H bonds into C-halogen bonds was achieved using a nano Ag/AgCl catalyst at RT under visible light or LED irradiation in the presence of an aqueous solution of NaX/HX as a halide source, in air. The halogenation of hydrocarbons provided mono-halide substituted products with 95% selectivity and yields higher than 90%, with the chlorination of toluene being 81%, far higher than the 40% conversion using dichlorine. Mechanistic studies demonstrated that the reaction is a free radical process using blue light (450-500 nm), with visible light being the most effective light source. Irradiation is proposed to cause AgCl bonding electrons to become excited and electron transfer from chloride ions induces chlorine radical formation which drives the substitution reaction. The reaction provides a potentially valuable method for the direct chlorination of saturated hydrocarbons.
- Liu, Shouxin,Zhang, Qi,Tian, Xia,Fan, Shiming,Huang, Jing,Whiting, Andrew
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p. 4729 - 4737
(2018/10/23)
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- Carbocation Catalyzed Bromination of Alkyl Arenes, a Chemoselective sp3 vs. sp2 C?H functionalization.
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The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl-arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N-bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron-rich alkyl-arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C?H functionalization and arene sp2 C?H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one-pot reaction of 1-methylnaphthalene for direct introduction of both sp3 C?Br and sp2 C?Br functionality. (Figure presented.).
- Ni, Shengjun,El Remaily, Mahmoud Abd El Aleem Ali Ali,Franzén, Johan
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supporting information
p. 4197 - 4204
(2018/09/25)
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- Photocatalytic Oxidative Bromination of Electron-Rich Arenes and Heteroarenes by Anthraquinone
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The estimated excited oxidation potential of sodium anthraquinone-2-sulfonate (SAS) increases from 1.8 V to about 2.3 V vs SCE by protonation with Br?nsted acids. This increased photooxidation power of protonated anthraquinone was used for the regio-selective oxidative bromination of electron rich (hetero)arenes and drugs in good yield. The mild reaction conditions are compatible with many functional groups, such as double and triple bonds, ketones, amides and amines, hydroxyl groups, carboxylic acids and carbamates. Mechanistic investigations indicate the photooxidation of the arene followed by nucleophilic bromide addition as the likely pathway. (Figure presented.).
- Petzold, Daniel,K?nig, Burkhard
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supporting information
p. 626 - 630
(2017/11/22)
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- SYSTEM AND METHOD FOR PREPARING AROMATIC DERIVATIVE
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A system for preparing an aromatic derivative is provided, including: a photo-bromination reaction section for performing a photocatalytic reaction of an aromatic hydrocarbon and a brominating agent to form an aromatic hydrocarbon bromide; a substitution reaction section for performing a substitution reaction of the an aromatic hydrocarbon bromide from the photo-bromination reaction section with an alkali base compound or an alkali carboxylate compound to form an aromatic derivative; and a regeneration unit for reacting an alkali metal bromide formed by the substitution reaction section with an acid to form a hydrobromic acid. The regeneration unit is in fluid communication with the photo-bromination reaction section, such that the hydrobromic acid is recycled to the photo-bromination reaction section. A method for preparing the aromatic derivative is also provided.
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Page/Page column 0085-0086
(2018/03/25)
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- Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
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Benzylic sp 3 C-H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO 2 Et, CO 2 H, CN or NO 2, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.
- Zhao, Mengdi,Li, Meiqi,Lu, Wenjun
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supporting information
p. 4933 - 4939
(2018/12/14)
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- Catalytic Bromination of Alkyl sp3C-H Bonds with KBr/Air under Visible Light
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Alkyl sp3C-H bonds of cycloalkanes and functional branch/linear alkanes have been successfully brominated with KBr using air or O2 as an oxidant at room temperature to 40 °C. The reactions are carried out in the presence of catalytic NaNO2 in 37% HCl (aq)/solvent under visible light, combining aerobic oxidations and photochemical radical processes. For various alkane substrates, CF3CH2OH, CHCl3, or CH2Cl2 is employed as an organic solvent, respectively, to enhance the efficiency of bromination.
- Zhao, Mengdi,Lu, Wenjun
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supporting information
p. 5264 - 5267
(2018/09/12)
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- An efficient conversion of alcohols to alkyl bromides using pyridinium based ionic liquids: A green alternative to appel reaction
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Pyridinium based ionic liquids namely 4-alkylpyridinium bromides were prepared and used for the conversion of alcohols to alkyl bromides in the presence of p-toluenesulphonic acid in the absence of volatile organic compounds. This solvent free procedure promises to be a much improved and environmentally benign alternative to the Appel reaction.
- Das, Pranab J.,Das, Jupitara,Das, Dimpee
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p. 651 - 654
(2018/02/09)
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- Ferric(III) Chloride Catalyzed Halogenation Reaction of Alcohols and Carboxylic Acids Using α,α-Dichlorodiphenylmethane
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A new method for chlorination of alcohols and carboxylic acids, using α,α-dichlorodiphenylmethane as the chlorinating agent and FeCl3 as the catalyst, was developed. The method enables conversions of various alcohols and carboxylic acids to their corresponding alkyl and acyl chlorides in high yields under mild conditions. Particulary interesting is the observation that the respective alkyl bromides and iodides can be generated from alcohols when either LiBr or LiI are present in the reaction mixtures.
- Lee, Chang-Hee,Lee, Soo-Min,Min, Byul-Hana,Kim, Dong-Su,Jun, Chul-Ho
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supporting information
p. 2468 - 2471
(2018/04/25)
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- BBr3-Assisted Preparation of Aromatic Alkyl Bromides from Lignin and Lignin Model Compounds
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For the first time, BBr3-assisted nucleophilic substitution was applied to a variety of β-O-4 and α-O-4 model compounds for the highly effective cleavage of different C-O bonds, including C-Oα-OH, Cβ-O/Cα-O and CMe-O bonds (99% conversion for most cases). Without any pretreatment, the substitution proceeds at room temperature in the absence of any catalyst, or additive, selectively affording phenols and important organic synthesis reagents, aromatic alkyl bromides, in high to excellent yields (up to 98%). Preliminary studies also highlight the prospect of this method for the effective cleavage of different types of C-O bonds in real lignin. A total 14 wt % yield of aromatic alkyl bromide, 4-(1,2-dibromo-3-hydroxypropyl)benzene-1,2-diol (10), has been obtained from an extracted lignin through this method.
- Li, Xuan,He, Jianghua,Zhang, Yuetao
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supporting information
p. 11019 - 11027
(2018/09/06)
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- By nucleophilic substitution reaction to degrade lignin and lignin model compounds (by machine translation)
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The invention through the nucleophilic substitution reaction to degrade lignin and lignin model compound method relates to biomass energy chemical technical field. In order to lignin model compounds and organic solvent-soluble lignin as substrate, to halogenated compound B BX3 As nucleophiles, through the nucleophilic substitution reaction, in - 78 °C to 60 °C conditions, reaction 0.5 h - 36 h, at the same time realize lignin model compound, lignin degradation, and the connection of the X substituent. The operation of the invention the method is simple, mild reaction conditions, not only high conversion and high selectivity (>99% conversion rate, close to 99% [...] selective) realizes the lignin and the degradation of lignin model compound, and obtained the degradation product, is a very high can be modified with the nature contains the bromine compound, can be used as an important organic synthetic intermediates. (by machine translation)
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-
Paragraph 0056; 0057
(2018/04/03)
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- Hydrodebromination of allylic and benzylic bromides with water catalyzed by a rhodium porphyrin complex
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Hydrodebromination of allylic and benzylic bromides was successfully achieved by a rhodium porphyrin complex catalyst using water as the hydrogen source without a sacrificial reductant. Mechanistic investigations suggest that bromine atom abstraction via a rhodium porphyrin metalloradical operates to give the rhodium porphyrin alkyl species and the subsequent hydrolysis of the rhodium porphyrin alkyl species to a hydrocarbon product is a key step to harness the hydrogen from water.
- Yang, Wu,Chen, Chen,Chan, Kin Shing
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p. 12879 - 12883
(2018/10/02)
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- Method for preparing benzyl bromide
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The invention provides a method for preparing benzyl bromide. The method comprises the following steps: by taking bromine released from a redox reaction between bromates and negative bromide ions in the presence of an acid as a bromine source in an organic solvent, carrying out a benzyl radical substitution reaction with a methylbenzene compound shown as a formula I under initiation of an initiator, thereby obtaining a corresponding benzyl bromide compound shown a formula II, wherein in the formula II, m represents the number of Br and is equal to 1 or 2; when m is equal to 1, the formula II shows a benzyl monobromo compound; and when m is equal to 2, the formula II shows a benzyl dibromo compound. The reaction is carried out in an organic solvent, the initiator is combined and used, the radical substitution reaction is high in selectivity and wide in substrate application range, the substituent group replacing methylbenzene may be an electron-withdrawing group or an electron-donating group and can give extremely high yield on strong electron-donating groups (such as methoxy group). Moreover, the method disclosed by the invention is also applicable to preparation of benzyl dibromo compounds, and the product yield is high.
- -
-
Paragraph 0034-0036
(2017/10/05)
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- Synthesis of Phenanthridines through Palladium-Catalyzed Cascade Reaction of 2-Halo-N-Ms-arylamines with Benzyl Halides/Sulfonates
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An efficient palladium-catalyzed nucleophilic substitution/C–H activation/aromatization cascade reaction between readily available 2-halo-N-Ms-arylamines (Ms = methanesulfonyl) and benzyl halides/sulfonates has been described. A wide variety of phenanthridines were synthesized in a one-pot fashion in moderate to high yields (37–86 %). Notably, this method provides a straightforward, facile approach for the synthesis of phenanthridines. The practicality was further substantiated by successfully carrying out a gram-scale preparation.
- Yang, Si-Yi,Han, Wen-Yong,Zhang, Ding-Lei,Zhou, Xiao-Jian,Bai, Mei,Cui, Bao-Dong,Wan, Nan-Wei,Yuan, Wei-Cheng,Chen, Yong-Zheng
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p. 996 - 1003
(2017/02/15)
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- Preparation of manganese/Graphite oxide composite using permanganate and graphite: Application as catalyst in bromination of hydrocarbons
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A highly efficient one-pot preparation of manganese/graphite oxide (MnOX/GO) composite from graphite and KMnO4 is described. Hummers preparation method of GO requires a stoichiometric amount of KMnO4, as a result, the method produces a large amount of reduced Mn species. The Mn residue generally is a waste, therefore, we envisioned converting it to value-Added materials. A MnOX/GO composite was prepared in one-pot by treating the unpurified GO with aqueous KOH. The composite was characterized by XRD, XAFS, SEM and TEM. Among various applications of the MnOX/GO composite, we applied it as a recyclable catalyst for bromination of saturated hydrocarbons, one of the most basic but important chemical transformations. The MnOX/GO composite is expected to be an efficient catalyst because of the high surface area and high accessibility of substrates derived from the 2- dimensional sheet structure. When the reaction of a saturated hydrocarbon and Br2 in the presence of catalytic MnOX/GO was performed under fluorescent light irradiation, a brominated product was formed in high yield in a short reaction time. GO could strongly bind with Mn to prevent elution to the liquid phase, enabling the high recyclability.
- Suzuki, Hideyuki,Nishina, Yuta
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- Development of an indicator for the direct visualization of radical intermediates in organic reactions
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A color-indicator based on a derivative of rhodamine amide was developed for the detection of radical intermediates in organic reactions. This derivative showed sensitive color changes for various radical intermediates initiated by chemical reagents or UV
- Yao, Qiuli,Li, Chao-Jun
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supporting information
p. 11225 - 11228
(2017/10/17)
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- Synthesis and biological evaluation of curcumin inspired indole analogues as tubulin polymerization inhibitors
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In our endeavour towards the development of potent cytotoxic agents, a series of some new curcumin inspired indole analogues, in which indole and phenyl moieties are linked on either sides of 1,5-diaryl-1,4-pentadien-3-one system have been synthesized and characterized by spectral data. All the newly synthesized analogues were tested for their cytotoxic potential against a panel of eight cancer cell lines namely, lung (A549), breast (MDA-MB-231, BT549 and 4T1), prostate (PC-3, DU145), gastric (HGC-27) and cervical (HeLa). Notably, among all the compounds tested, compounds 11c, 11d and 11f showed potent growth inhibition on PC-3 and BT549 with IC50values in the range of 3.12–6.34?μM and 4.69–8.72?μM respectively. The most active compound (11c) was also tested on RWPE-1 (normal prostate) cells and was found to be safe compared to the PC-3?cells. In tubulin polymerization assay, compounds 11c and 11f effectively inhibited microtubule assembly with IC50values of 10.21?±?0.10 and 8.83?±?0.06?μM respectively. The results from molecular modelling studies revealed that these compounds bind at the colchicine binding site of the tubulin. Moreover, DAPI and acridine orange/ethidium bromide staining studies indicated that compounds 11c and 11f can induce apoptosis in PC-3?cells. Further flow-cytometry analysis revealed that compound 11c arrests PC-3?cells in G2/M phase of the cell cycle while compound 11f treatment resulted in moderate increase in the G2/M population. Additionally, the treatment by these compounds led to the impairment of mitochondrial membrane potential (DΨm) in PC-3?cells.
- Sri Ramya,Angapelly, Srinivas,Guntuku, Lalita,Singh Digwal, Chander,Nagendra Babu, Bathini,Naidu,Kamal, Ahmed
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p. 100 - 114
(2016/12/30)
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- Preparation and properties of a novel solution of hydrogen bromide (HBr) in 1,4-dioxane: An alternative reagent to HBr gas without protic solvents
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A solution of hydrogen bromide (HBr) in 1,4-dioxane was prepared and investigated for its ability to brominate alcohols, and hydrobrominate alkenes. This study revealed that the brominating ability of this HBr/1,4-dioxane solution is equal or superior to that of hydrobromic acid or HBr in acetic acid. The solution of HBr in 1,4-dioxane is robust, exhibiting no decomposition of the solvent, and retaining 97% of its original concentration, when kept at ?25 °C for 30 days. This solution is a liquid alternative to HBr gas without protic solvents.
- Nishio, Yuya,Mifune, Ryota,Sato, Taisuke,Ishikawa, Shin-ich,Matsubara, Hiroshi
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supporting information
p. 1190 - 1193
(2017/03/02)
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- PROCESS FOR THE PREPARATION OF ORGANIC BROMIDES
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The present invention provides a process for the preparation of organic bromides, by a radical bromodecarboxylation of carboxylic acids with a bromoisocyanurate.
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Paragraph 00169; 00177
(2017/07/28)
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- Cleavage of ethers in an ionic liquid. Enhancement, selectivity and potential application
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The cleavage of a series of ethers was examined in an ionic liquid containing hydrogen bromide. Reactions that did not proceed in either water or DMSO were found to proceed readily in this system, with notable selectivity between the cleavage of the different ether types examined herein. Increasing the proportion of water in the reaction mixture dramatically decreased the rate constant of ether cleavage; this could, in part, be attributed to a decrease in the solvent stabilisation of the transition state. Through analysis of the electronic requirements of the reaction (using substrates containing substituents with different Hammett parameters) and observation of rate enhancements for an ortho substituted system, the importance of the extent of protonation of the ether prior to nucleophilic attack was demonstrated.
- Hart, William E. S.,Aldous, Leigh,Harper, Jason B.
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supporting information
p. 5556 - 5563
(2017/07/12)
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- Bent-core mesogens with an aromatic unit at the terminal position
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Bent-core liquid crystals with a naphthalene central unit and an aromatic ring at the terminal position of molecular tails were synthesised with the aim of enhancing nanosegregation. It was found that the length of the spacer between the rigid core and the terminal aromatic moiety had a profound influence on the liquid crystal polymorphism. The homologues with short spacers exhibited nematic and columnar phases, whereas the homologue with long spacers exhibited a tilted lamellar phase with a liquid-like in-plane order, indicating an unusual morphology of the densely packed toroidal objects. The morphology can be changed to twisted ribbons by small additives adsorbed on the membrane surface. This is the first example of twisted ribbons constructed by a lamellar system with no long-range in-plane order.
- Bajzíková, Kvetoslava,Svoboda, Ji?í,Novotná, Vladimíra,Pociecha, Damian,Gorecka, Ewa
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supporting information
p. 4672 - 4679
(2017/07/10)
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- Improved Halogenation of Methyl Aromatics and Methyl Heteroaromatics: Unexpected Reactivity of Tetrahalogeno-diphenylglycolurils
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1,3,4,6-Tetrachloro (TCDGU) and 1,3,4,6-tetrabromo-3α,6α-diphenylglycolurils smooth halogen oxidizers have been exploited in a new direction as reagents for free radical substitution toward some N-halosuccinimide nonreactive bis-heterocycles. An unexpected selectivity and reactivity were observed with methyl benzenes, methyl heterocycles, and methyl-bis-heterocycles of interest. A chemometric study has been performed to optimize five independent factors of the chlorination reaction with TCDGU. The predictive model was established either for the halogenation conversion and the ratio of monochlorination.
- Moretti, Florian,Poisson, Guillaume,Marsura, Alain
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p. 173 - 183
(2016/05/19)
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- Preparation method of benzylamine compound
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The invention discloses a preparation method of a benzylamine compound. The method adopting an aryl methane compound as a raw material comprises the following steps: carrying out an NBS bromination reaction to synthesize a bromobenzyl compound, carrying out an N-hydrocarbylation reaction to synthesize a 1-benzylpyrrolidyl-2,5-dione compound, and carrying out a hydrolyzing reaction to obtain the benzylamine compound. The preparation method of the benzylamine compound has the advantages of wide source of the raw material, no need of separation of intermediates generated in above reactions, realization of an all-in-a-pot technology, simple operation, mild reaction conditions, high reaction yield, few three wastes, and convenience for industrial production.
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Paragraph 0038-0040
(2017/01/23)
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- Modeling Non-Heme Iron Halogenases: High-Spin Oxoiron(IV)-Halide Complexes That Halogenate C-H Bonds
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The non-heme iron halogenases CytC3 and SyrB2 catalyze C-H bond halogenation in the biosynthesis of some natural products via S = 2 oxoiron(IV)-halide intermediates. These oxidants abstract a hydrogen atom from a substrate C-H bond to generate an alkyl radical that reacts with the bound halide to form a C-X bond chemoselectively. The origin of this selectivity has been explored in biological systems but has not yet been investigated with synthetic models. Here we report the characterization of S = 2 [FeIV(O)(TQA)(Cl/Br)]+ (TQA = tris(quinolyl-2-methyl)amine) complexes that can preferentially halogenate cyclohexane. These are the first synthetic oxoiron(IV)-halide complexes that serve as spectroscopic and functional models for the halogenase intermediates. Interestingly, the nascent substrate radicals generated by these synthetic complexes are not as short-lived as those obtained from heme-based oxidants and can be intercepted by O2 to prevent halogenation, supporting an emerging notion that rapid rebound may not necessarily occur in non-heme oxoiron(IV) oxidations.
- Puri, Mayank,Biswas, Achintesh N.,Fan, Ruixi,Guo, Yisong,Que, Lawrence
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p. 2484 - 2487
(2016/03/12)
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- Synthesis and bioactivity of novel triazole incorporated benzothiazinone derivatives as antitubercular and antioxidant agent
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In search of new active molecules against Mycobacterium tuberculosis (MTB) H37Ra and M. bovis BCG, a small focused library of benzothiazinone based 1,2,3-triazoles has been efficiently prepared via click chemistry approach. Several derivatives were found to be promising inhibitors of MTB and M. bovis BCG characterized by lower MIC values (27.34-29.37 μg/mL). Among all the synthesized compounds, 6c and 6e is the most active compound against MTB and M. bovis BCG. The compounds were further tested for anti-proliferative activity against HeLa, A549 and A431 cell lines using MTT assay and showed no significant cytotoxic activity at the maximum concentration evaluated. Further, the synthesized compounds were found to have potential antioxidant activity with IC50 range = 14.14-47.11 μg/mL. Furthermore, to rationalize the observed biological activity data, the molecular docking study also been carried out against a potential target MTB DprE1, which revealed a significant correlation between the binding score and biological activity for these compounds. The results of the in vitro and in silico study suggest that the triazole incorporated benzothiazinone may possess the ideal structural requirements for further development of novel therapeutic agents.
- Shaikh, Mubarak H.,Subhedar, Dnyaneshwar D.,Arkile, Manisha,Khedkar, Vijay M.,Jadhav, Nandadeep,Sarkar, Dhiman,Shingate, Bapurao B.
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p. 561 - 569
(2016/01/09)
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