- 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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- Thiourea-Catalyzed C?F Bond Activation: Amination of Benzylic Fluorides
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We describe the first thiourea-catalyzed C?F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.
- Houle, Camille,Savoie, Paul R.,Davies, Clotilde,Jardel, Damien,Champagne, Pier Alexandre,Bibal, Brigitte,Paquin, Jean-Fran?ois
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p. 10620 - 10625
(2020/07/24)
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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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- Discovery and structural optimization of 4-(4-(benzyloxy)phenyl)-3,4-dihydropyrimidin-2(1H)-ones as RORc inverse agonists
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Aim: Retinoic acid receptor-related orphan nuclear receptors (RORs) are orphan nuclear receptors that show constitutive activity in the absence of ligands. Among 3 subtypes of RORs, RORc is a promising therapeutic target for the treatment of Th17-mediated autoimmune diseases. Here, we report novel RORc inverse agonists discovered through structure-based drug design. Methods: Based on the structure of compound 8, a previously described agonist of RORa, a series of 4-(4-(benzyloxy)phenyl)-3,4-dihydropyrimidin-2(1H)-one derivatives were designed and synthesized. The interaction between the compounds and RORc was detected at molecular level using AlphaScreen assay. The compounds were further examined in 293T cells transfected with RORc and luciferase reporter gene. Thermal stability shift assay was used to evaluate the effects of the compounds on protein stability. Results: A total of 27 derivatives were designed and synthesized. Among them, the compound 22b was identified as the most potent RORc inverse agonist. Its IC50 values were 2.39 μmol/L in AlphaScreen assay, and 0.82 μmol/L in inhibition of the cell-based luciferase reporter activity. Furthermore, the compound 22b displayed a 120-fold selectivity for RORc over other nuclear receptors. Moreover, a molecular docking study showed that the structure-activity relationship was consistent with the binding mode of compound 22b in RORc. Conclusion: 4-(4-(Benzyloxy)phenyl)-3,4-dihydropyrimidin-2(1H)-one derivatives are promising candidates for the treatment of Th17-mediated autoimmune diseases, such as rheumatoid arthritis, psoriasis, and multiple sclerosis.
- Wu, Xi-Shan,Wang, Rui,Xing, Yan-Li,Xue, Xiao-Qian,Zhang, Yan,Lu, Yong-Zhi,Song, Yu,Luo, Xiao-Yu,Wu, Chun,Zhou, Yu-Lai,Jiang, Jian-Qin,Xu, Yong
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p. 1516 - 1524
(2016/11/11)
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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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- Clay-Supported Cu(II) Catalyst: An Efficient, Heterogeneous, and Recyclable Catalyst for Synthesis of 1,4-Disubstituted 1,2,3-Triazoles from Alloxan-Derived Terminal Alkyne and Substituted Azides Using Click Chemistry
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A novel series of alloxan-derived 1,4-disubstituted 1,2,3-triazoles was synthesized in excellent yields under catalytic conditions using a click reaction strategy through 1,3-dipolar cycloaddition. Their structures have been ascertained on the basis of spectroanalytical and elemental analysis data. Synthesis of hybrid compounds with varying substitutions in the triazole ring was achieved by reaction between alloxan-derived terminal alkyne and a pertinent azide derivative in the presence of clay-Cu(II) as the catalyst in methanolic medium. Also, comparative evaluation of various catalytic systems [viz., CuI, CuSO4, CuI-zeolite, K10Ti, and clay-Cu(II)] was investigated. Of these catalytic systems, clay-Cu(II) was observed to be the best. The catalyst was recyclable for several runs without showing significant loss in its activity. The good selectivity, cost-efficiency, short reaction time, milder reaction conditions, and simple workup procedure are the added salient features of this synthetic protocol.
- Dubey, Nitin,Sharma, Pratibha,Kumar, Ashok
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p. 2608 - 2626
(2015/11/28)
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- Tribromoisocyanuric acid as a green reagent for benzylic bromination of alkylarenes
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The reaction of diverse alkylarenes with tribromoisocyanuric acid (0.34 mol equiv) in reflux EtOAc in the absence of any catalysts or light irradiation produced the corresponding benzyl bromides in 53-88% yield.
- De Almeida, Leonardo S.,Esteves, Pierre M.,De Mattos, Marcio C.S.
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p. 6843 - 6845
(2015/11/27)
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- A scalable procedure for light-induced benzylic brominations in continuous flow
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A continuous-flow protocol for the bromination of benzylic compounds with N-bromosuccinimide (NBS) is presented. The radical reactions were activated with a readily available household compact fluorescent lamp (CFL) using a simple flow reactor design based on transparent fluorinated ethylene polymer (FEP) tubing. All of the reactions were carried out using acetonitrile as the solvent, thus avoiding hazardous chlorinated solvents such as CCl4. For each substrate, only 1.05 equiv of NBS was necessary to fully transform the benzylic starting material into the corresponding bromide. The general character of the procedure was demonstrated by brominating a diverse set of 19 substrates containing different functional groups. Good to excellent isolated yields were obtained in all cases. The novel flow protocol can be readily scaled to multigram quantities by operating the reactor for longer time periods (throughput 30 mmol h-1), which is not easily possible in batch photochemical reactors. The bromination protocol can also be performed with equal efficiency in a larger flow reactor utilizing a more powerful lamp. For the bromination of phenylacetone as a model, a productivity of 180 mmol h -1 for the desired bromide was achieved.
- Cantillo, David,De Frutos, Oscar,Rincon, Juan A.,Mateos, Carlos,Oliver Kappe
-
supporting information
p. 223 - 229
(2014/01/17)
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- On the ionizing properties of supercritical carbon dioxide: Uncatalyzed electrophilic bromination of aromatics
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Supercritical carbon dioxide (scCO2), a solvent with a zero dipole moment, low dielectric constant, and no hydrogen bonding behavior, is a suitable medium to perform the uncatalyzed electrophilic bromination of weakly activated aromatics with no interference of radical pathways. The ability of scCO2 to promote these reactions matches those of strongly ionizing solvents such as aqueous acetic and trifluoroacetic acids. Conversely, carbon tetrachloride, with similar polarity parameters to scCO2, leads exclusively to side chain functionalization. The strong quadrupole moment, and the acidic, but non basic, Lewis character of carbon dioxide, are proposed as key factors for the singular performance of scCO2 in reactions involving highly polar and ionic intermediates.
- Delgado-Abad, Thais,Martnez-Ferrer, Jaime,Reig-Lpez, Javier,Mello, Rossella,Acerete, Rafael,Asensio, Gregorio,Gonzlez-Nez, Mara Elena
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p. 51016 - 51021
(2015/01/16)
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- Synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters from arylmethyl azides via a domino process
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A convenient synthesis of 2,4-unsubstituted quinoline-3-carboxylic acid ethyl esters via a domino process is described. The synthesis employs arylmethyl azides as the precursor which undergoes an acid-promoted rearrangement to give an N-aryl iminium ion. Following the addition with ethyl 3-ethoxyacrylate, intramolecular electrophilic aromatic substitution, elimination and subsequent oxidation, the quinoline products were obtained in moderate to excellent yields.
- Tummatorn, Jumreang,Thongsornkleeb, Charnsak,Ruchirawat, Somsak,Gettongsong, Tanita
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supporting information
p. 1463 - 1467
(2013/05/08)
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- Polyvinylpyrrolidone-bromine complex: An efficient polymeric reagent for selective preparation of benzyl bromides in the presence of hexamethyldisilane
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Benzylic bromides were conveniently obtained in high yields via the reaction of the corresponding alcohols with crosslinked polyvinylpyrrolidone- bromine complex (PVPP-Br2)/hexamethyldisilane in chloroform at reflux condition. Selective conversion of benzyl alcohol to benzyl bromide in the presence of primary aliphatic alcohols, e.g. 2-phenylethanol was also achieved.
- Mokhtary, Masoud,Lakouraj, Moslem M.
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p. 305 - 309
(2012/10/29)
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- Efficient organic transformations mediated by ZrOCl28H 2O in Water
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Operationally simple and environmentally benign methods for some organic transformations comprising reductive coupling of sulfonyl chlorides, chemoselective deoxygenation of sulfoxides, and halogenation of alcohols mediated by ZrOCl28H2O/MX in water have been developed.
- Jafarpour, Maasoumeh,Rezaeifard, Abdolreza,Heidari, Mahdieh
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experimental part
p. 1470 - 1482
(2011/10/05)
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- Synthesis of benzyl bromides with hexabromoacetone: An alternative path to drug intermediates
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A series of benzyl bromides were efficiently prepared from the corresponding alcohols with Br3CCOCBr3/PPh3 at low temperatures and under neutral conditions. The present protocol was applied to the heterocyclic analogues and to the successful synthesis of the precursor of the antiulcer drug omeprazole, thus furnishing an alternate, mild method for the preparation of these drug intermediates. A significant steric factor was observed throughout both series supporting a SN2 mechanism.
- Joseph, Kara M.,Larraza-Sanchez, Isabel
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experimental part
p. 13 - 16
(2011/02/25)
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- N-Halosuccinimide/SiCl4 as general, mild and efficient systems for the α-monohalogenation of carbonyl compounds and for benzylic halogenation
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Combinations of N-halosuccinimide and tetrachlorosilane in acetonitrile were found to be efficient systems for the selective α-monohalogenation of carbonyl compounds as well as for benzylic halogenation under mild conditions.
- Salama, Tarek A.,Novák, Zoltán
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experimental part
p. 4026 - 4029
(2011/08/09)
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- PHENYLENE OXO-DIESTER PLASTICIZERS AND METHODS OF MAKING
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A process for making non-phthalate, 1,2-phenylene oxo-diester plasticizers for polymer compositions, by selectively hydrogenating naphthalene to form a partially hydrogenated naphthalene, oxygenating said partially hydrogenated naphthalene to form phenylene diacids, and esterifying said phenylene diacids with oxo-alcohols to form 1,2-phenylene oxo-diesters. Also a process for making phenylene oxo-diester plasticizers by selectively brominating xylenes to form bisbromomethylbenzene, catalytic carboalkoxylation of the bromo-compound to form phenylene diacetate, followed by transesterification to form the phenylene oxo-diester.
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Page/Page column 13; 19
(2011/04/25)
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- A simple and efficient total synthesis of (±)-danshexinkun A, a bioactive diterpenoid from Salvia miltiorrhiza
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An efficient 12-step route for the synthesis of the diterpenoid quinone (±)-danshexinkun A in 23% overall yield from the corresponding highly substituted stilbene using a photocyclization strategy is described.
- Moghaddam, Firouz Matloubi,Farimani, Mahdi Moridi
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supporting information; experimental part
p. 540 - 542
(2010/10/02)
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- Visible-light-promoted Wohl-Ziegler functionalization of organic molecules with N-bromosuccinimide under solvent-free reaction conditions
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The visible-light-induced transformation of toluenes with N-bromosuccinimide (NBS) under solvent-free reaction conditions (SFRC) was studied. The reaction took place in spite of the very restricted molecular motion; toluenes could be regioselectively converted to benzyl bromides. Selective radical-chain reactions with NBS were carried out in liquid/liquid and in solid/solid systems; furthermore, reactions could be performed in the presence of air. The radical scavenger TEMPO (=2,2,6,6-tetramethylpiperidin-1- yloxy) completely suppressed the side-chain bromination of toluenes with NBS under SFRC. Electron-withdrawing groups decreased the reactivity of the toluenes, and the Hammett reaction constant ρ+ = -1.7 indicated involvement of polar radical intermediates with electrophilic character.
- Jereb, Marjan,Zupan, Marko,Stavber, Stojan
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experimental part
p. 555 - 566
(2009/09/06)
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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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scheme or table
p. 1861 - 1865
(2009/07/19)
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- Benzylic brominations with N-bromosuccinimide in (Trifluoromethyl)benzene
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A variety of benzylic brominations were performed by using N-bromosuccinimide in (trifluoromethyl)benzene with photochemical activation in the presence of 2,2′-azobisisobutyronitrile, 1,1′- azobis(cyclohexanecarbonitrile), or benzoyl peroxide as the radical initiator. This system provides clean, rapid, and high-yielding reactions with replacement of conventional solvents, such as tetrachloromethane, by less-toxic (trifluoromethyl)benzene. Georg Thieme Verlag Stuttgart.
- Suarez, Diana,Laval, Gilles,Tu, Shang-Min,Jiang, Dong,Robinson, Claire L.,Scott, Richard,Golding, Bernard T.
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experimental part
p. 1807 - 1810
(2010/02/28)
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- Contrasting chemoselectivities in the ultrasound and microwave assisted bromination reactions of substituted alkylaromatics with N-bromosuccinimide
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Ultrasound and microwave assisted bromination reactions of various alkylaryls with N-bromosuccinimide, either neat or in water, shows diverse chemoselectivity. Thus, ring substitution occurs in water with ultrasound, whereas with microwaves both side-chain α-bromination and ring substitution occur. With neat reactants, side-chain α-bromination predominates for microwave assisted reactions. In the presence of water the chemoselectivity with microwave-promoted bromination is similar to that observed using classical methods.
- Heropoulos, Georgios A.,Cravotto, Giancarlo,Screttas, Constantinos G.,Steele, Barry R.
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p. 3247 - 3250
(2008/02/02)
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- Regioselective photochemical and microwave mediated monobromination of aromatic compounds using 2,4,4,6-tetrabromo-2,5-cyclohexadienone
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Bromination of different aromatic substrates have been described using 2,4,4,6-tetrabromo-2,5-cyclohexadienone in conjunction with microwave and ultraviolet radiations. Important features of the work include high regioselectivity obtained in very short to moderate reaction time, atom economy, and recyclability of the reagent. Copyright Taylor & Francis Group, LLC.
- Gupta, Neeraj,Kad, Goverdhan L.,Singh, Vasundhara,Singh, Jasvinder
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p. 3421 - 3428
(2008/02/12)
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- Free radical bromination by the H2O2-HBr system on water
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An aqueous solution of hydrogen peroxide and hydrogen bromide illuminated by a 40 W incandescent light bulb serves as a source of bromine radicals. Various substituted toluenes (H, Me, tBu, Br, COOEt, COPh, NO2) were brominated at the benzyl position. This haloperoxidase-like system for benzylic bromination does not require the presence of metal ions or an organic solvent for efficient conversion of methyl-arenes to benzyl bromides.
- Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
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p. 7245 - 7247
(2007/10/03)
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- Side chain bromination of mono and dimethyl heteroaromatic and aromatic compounds by solid phase N-bromosuccinimide reaction without radical initiator under microwave
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A series of side chain mono and dibromo derivatives of mono and dimethyl heteroaromatic and aromatic compounds (1-17) were synthesized by one step solid phase N-bromosuccinimide (NBS) reaction without radical initiator by microwave irradiation. The benzylic mono and dibromo products were exclusively preferred except in the case of 6-methylpyridine amides (8 and 9) where nuclear and also side chain bromination resulted. Naphthyridine systems resulted improved yields. By this method, we also report the synthesis of 2-pivaloylaminopterin-6- carbaldehyde.
- Goswami, Shyamaprosad,Dey, Swapan,Jana, Subrata,Adak, Avijit Kumar
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p. 916 - 917
(2007/10/03)
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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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p. 190 - 191
(2013/09/06)
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- Reductive bromination of aromatic aldehydes using alkylboron dibromides
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The reductive bromination of aromatic aldehydes with isopinocampheyl boron dibromide in hexane at room temperature produces the corresponding benzyl bromides in excellent yields. (C) 2000 Elsevier Science Ltd.
- Kabalka, George W.,Wu, Zhongzhi,Ju, Yuhong
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p. 5161 - 5164
(2007/10/03)
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- A process for the production of benzene derivatives
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The present invention relates to a process for the production of benzene derivatives as compounds of chemical formula ( I ) below which are used as intermediates of agricultural chemical, fine chemical products or pharmaceuticals such as anti inflammatory analgesics. The process for the production of benzene derivatives of present invention expressed in below chemical formula ( I ) is characterized by making reaction between compound of chemical formula ( II ) and hydrofomylating agent under halogenation agent. In chemical formula ( I ) and ( II ), X is halogenic atom, R1& R2are same or different each other, R1is hydrogen atom or low alkyl radical of carbon number 1 ~ 6, R2is hydrogen atom or COOR3, and R3is hydrogen atom or low alkyl radical of carbon number 1 ~ 6.
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- Scavenger assisted combinatorial process for preparing libraries of tertiary amine compounds
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This invention relates to a novel solution phase process for the preparation of tertiary amine combinatorial libraries. These libraries have utility for drug discovery and are used to form wellplate components of novel assay kits.
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- Selectivity in bromination of alkylbenzenes in the presence of montmorillonite clay
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Bromination of alkylbenzenes using bromine in carbon tetrachloride yields ring brominated products in the presence of K10-montmorillonite. In contrast, bromination without clay results only in side-chain bromination.
- Venkatachalapathy, Chockalingam,Pitchumani, Kasi
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p. 2581 - 2584
(2007/10/03)
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- Photolysis of a series of α-brominated ortho-xylenes in apolar solvents
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The α-brominated ortho-xylenes have been subjected to 254 nm irradiation in deaerated benzene, isooctane and benzene-cyclohexene.The product analysis revealed that homolysis of the C-Br bond is followed by a series of hydrogen abstraction and radical recombination reactions resulting in xylenes more and less brominated than the starting compound.The less brominated products are formed with higher quantum yield when cyclohexene is present, due to hydrogen abstraction by the o-benzyl radical formed initially, together with cyclohexene dimers.Additionally, the formation of 2-bromo-2,4,4-trimethylpentane is observed when isooctane is the solvent.The quantum yields observed for the photolysis of 1 and 2 are higher in benzene than in isooctane, suggesting sensitization by benzene.A biradical intermediate of the type o-quinodimethane was expected in the case of (a) photolysis of the o-benzyl radical formed (biphotonic process) or (b) intramolecular hydrogen abstraction.However, the addition of cyclohexene failed to produce the expected Diels-Alder adduct.The synthesis of the novel α,α-dibromo-o-xylene 3 is reported.
- Rezende, Daisy de B.,Campos, Ivan P. de Arruda,Toscano, Vicente G.,Catalani, Luiz H.
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p. 1857 - 1862
(2007/10/02)
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- Ultrasound promoted bromination of activated arenes with N-bromosuccinimide
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Ultrasound irradiation has resulted in the selective monobromination of activated aromatics with N-Bromosuccinimide (NBS) in carbon tetrachloride at ambient conditions in the absence of any added catalyst.
- Paul,Sudalai,Daniel,Srinivasan
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p. 2401 - 2405
(2007/10/02)
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- Preparation of 4-bromo-O-xylene using excess bromine
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A regioselective process is provided for preparing 4-bromo-o-xylene in an isomer mixture of 4-bromo-o-xylene and 3-bromo-o-xylene by combining a molar excess of bromine with o-xylene. The produced 3-bromo-o-xylene isomer preferentially reacts with the excess bromine to produce dibromo-o-xylenes. The weight ratio of the 4-bromo-o-xylene to the 3-bromo-o-xylene in the product isomer mixture can be as high as about 97:3. Concurrent production of alpha-bromo-o-xylene is avoided by conducting the admixing in either darkness or in sulfur dioxide solution. The dibromo-o-xylene by products are easily separated by subsequent vacuum distillation or similar expedients.
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- ORGANIC PHOSPHORUS COMPOUNDS 91. SYNTHESIS AND PROPERTIES OF 1-AMINO-2-ARYLETHYLPHOSPHONIC AND -PHOSPHINIC ACIDS AS WELL AS -PHOSPHINE OXIDES
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The preparation, physical and spectroscopic properties of 1-amino-2-arylethylphosphonic, and -phosphinic acids as well as -phosphine oxides, the phosphorus analogues of phenylalanine are described, and the reactions of 1-amino-2-(4-fluorophenyl)ethylphosphonates with acetals, isocyanides, esters, acid anhydrides, activated aromatic nitro- and halogen compounds, and with N-protected alanine are reported.It is shown that several of the 1-amino-2-arylethylphosphonic acids are strong inhibitors of PAL and anthocyanin synthesis and also are quite active botryticides.Among the active compounds were 1-amino-2-(4-fluorophenyl)ethylphosphonic acid, 3f, and the methyl-substituted compounds 3k, 3l, and 3m.The fluoroderivative 3f was also effective as a seed-dressing agent in barley showing a 100percent protection against the fungus Fusarium nivale at 600 ppm.
- Maier, Ludwig
-
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- Kinetics and Mechanism of Bromination of Toluene and Substituted Toluenes by N-Bromo Acetamide (NBA)
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Kinetics of bromination of toluene and substituted toluenes by N-Bromo Acetamide (NBA) in aqueous acetic acid perchloric acid medium has been reported.The reaction is first order in NBA, first order in substrate and fractional order in acid in case of toluene.In case of o-xylene, m-xylene and p-xylene the reaction is first order with respect to NBA, zero order in substrate and first order in acid.The effect of solvent composition has been investigated.Activation parameters have been computed.Suitable mechanism is postulated taking into consideration all the observed kinetic data.
- Pati, Subas C.,Pathy, H. P.,Dev, B. R.
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p. 385 - 391
(2007/10/02)
-
- Solvolysis of 2-substituted-9-(ortho-substituted) phenylmethyl)fluoren-9-yltrimethylammonium ions in various solvents
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The solvolytic reaction of several 9-(ortho-substituted phenylmethyl)fluoren-9-yltrimethylammonium salts has been investigated in several different solvents.Substitution and elimination products were found for the reactions in all solvents studied, with the exceptions that rection in both tert-butyl alcohol and chloroform led exclusively to the alkene product.The observed rate constants for alkene formation and the percent alkene were measured and it was found that the di-ortho compounds reacted at a faster rate but produced less alkene than the reaction of the corresponding mono-ortho salts.Hydrogen-deuterium isotope effects were also determined for the various reactions.The results are discussed in terms of the reaction proceeding by way of the E1 mechanism, where steric acceleration promotes the loss of the bulky ammonium leaving group to give the carbocation intermediate.
- Smith, Peter James,Pradhan, Jyotsna
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p. 1060 - 1071
(2007/10/02)
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- HOMOLYTIC DISPLACEMENT AT CARBON. X. TOLUENESULPHONYL IODIDE AS A SOURCE OF TOLUENESULPHONYL RADICALS FOR THE FORMATION OF ALLYL-, BENZYL-, CYCLOPROPYLCARBINYL-, SPIROCYCLOPROPYLCYCLOALKYL-, BICYCLOALKYL-, AND BICYCLOALKYL-4-TOLYLSULPHONES FROM ORGANOCOBALOXIMES
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4-Toluenesulphonyl iodide reacts thermally at alkylsulphone.Spiro- and bicyclo-alkyl compounds are also formed with other free radical precursors.The reactions are believed to take place through a chain mechanism in which cobaloxime(II), present adventitiously or formed by partial homolysis of the substrate, abstracts iodine from the toluenesulphonyl iodide to give the toluenesulphonyl radical, which attacks the organic ligand of the cobaloxime, preferably at the terminal olefinic carbon, thereby displacing cobaloxime(II) and giving the observed organic product.
- Ashcroft, Martyn R.,Bougeard, Peter,Bury, Adrian,Cooksey, Christopher J.,Johnson, Michael D.
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p. 403 - 416
(2007/10/02)
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- The easy preparation of many benzylic bromides using molecular bromine as a halogenating in the presence of catalytic amounts of lanthanum tri-acetate
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Many benzylic brominations were easily achieved by molecular bromine in CCl4 in presence of 1 percent of La (OAc)3 and a standard room lighting lamp.The selectivity is excellent except for certain electron-rich systems (p-methylaniline, p-cresol).
- Ouertani, Mohsen,Girard, Pierre,Kagan, Henry B.
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p. 327 - 328
(2007/10/02)
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- HOMOLYTIC DISPLACEMENT AT CARBON VI. SYNTHESIS OF TRICHLOROETHYLARENES FROM BENZYLCOBALOXIMES
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Benzylbis(dimethylglyoximato)pyridinecobalt(III) reacts with bromotrichloromethane at from 50 to 90 deg C in chloroform to give good yields of trichloroethylbenzene, which are higher when imidazole is present in the reaction mixture.Methyl- and polymethyl-substituted benzylbis(dimethylglyximato)pyridinecobalt(III) complexes give higher yields of the corresponding trichloroethylarenes (85-90percent), whereas 4-chlorobenzylbis(dimethylglyoximato)pyridinecobalt(III) only gives the 4-nitro-trichloroethylarene when imidazole is present during the reaciton.Similar reactions were observed with benzylcobaloximes and trichloromethanesulphonyl chloride both thermally and under irradiation by tungsten lamps through all-pyrex apparatus.The reactions are interpreted as a direct attack of the trichloromethyl radical on the α-carbon of the benzyl ligand.
- Bougeard, Peter,Gupta, B. Dass,Johnson, Michael D.
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p. 211 - 219
(2007/10/02)
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