- SYNTHESIS OF BENZO-1,4-DIOXANE IN THE PRESENCE OF INTERPHASE CATALYSTS
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Quaternary ammonium salts markedly accelerate the formation of benzo-1,4-dioxane from 1,2-dibromoethane and pyrocatechol under the influence of aqueous alkali and increase its yield.
- Lyushin, M.M.,Bakus, Yalda Pimanos,Budzema, Khamada
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Read Online
- Method for preparing aldehyde/ketone by breaking C-C key
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The invention discloses a method for preparing aldehyde/ketone by breaking C-C bonds, and the method comprises the following steps of anaerobic condition. In an organic solvent system, an alcohol is used as a reaction raw material, and the C-C bond is selectively broken under the common action of an iron catalyst, an organic base and an additive to obtain aldehyde/ketone. The method is low in cost, easy to obtain, wide in substrate range, simple and product in post-treatment and high in purity, a new synthetic route and a method are developed for an aldehyde ketone compound, and the method has good application potential and research value.
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Paragraph 0119-0122
(2021/11/19)
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- Ceramic boron carbonitrides for unlocking organic halides with visible light
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Photochemistry provides a sustainable pathway for organic transformations by inducing radical intermediates from substrates through electron transfer process. However, progress is limited by heterogeneous photocatalysts that are required to be efficient, stable, and inexpensive for long-term operation with easy recyclability and product separation. Here, we report that boron carbonitride (BCN) ceramics are such a system and can reduce organic halides, including (het)aryl and alkyl halides, with visible light irradiation. Cross-coupling of halides to afford new C-H, C-C, and C-S bonds can proceed at ambient reaction conditions. Hydrogen, (het)aryl, and sulfonyl groups were introduced into the arenes and heteroarenes at the designed positions by means of mesolytic C-X (carbon-halogen) bond cleavage in the absence of any metal-based catalysts or ligands. BCN can be used not only for half reactions, like reduction reactions with a sacrificial agent, but also redox reactions through oxidative and reductive interfacial electron transfer. The BCN photocatalyst shows tolerance to different substituents and conserved activity after five recycles. The apparent metal-free system opens new opportunities for a wide range of organic catalysts using light energy and sustainable materials, which are metal-free, inexpensive and stable. This journal is
- Yuan, Tao,Zheng, Meifang,Antonietti, Markus,Wang, Xinchen
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p. 6323 - 6332
(2021/05/19)
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- Iron-Catalyzed C-C Single-Bond Cleavage of Alcohols
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An iron-catalyzed deconstruction/hydrogenation reaction of alcohols through C-C bond cleavage is developed through photocatalysis, to produce ketones or aldehydes as the products. Tertiary, secondary, and primary alcohols bearing a wide range of substituents are suitable substrates. Complex natural alcohols can also perform the transformation selectively. A investigation of the mechanism reveals a procedure that involves chlorine radical improved O-H homolysis, with the assistance of 2,4,6-collidine.
- Liu, Wei,Wu, Qiang,Wang, Miao,Huang, Yahao,Hu, Peng
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supporting information
p. 8413 - 8418
(2021/11/01)
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- Light-Promoted Nickel Catalysis: Etherification of Aryl Electrophiles with Alcohols Catalyzed by a NiII-Aryl Complex
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A highly effective C?O coupling reaction of (hetero)aryl electrophiles with primary and secondary alcohols is reported. Catalyzed by a NiII-aryl complex under long-wave UV (390–395 nm) irradiation in the presence of a soluble amine base without any additional photosensitizer, the reaction enables the etherification of aryl bromides and aryl chlorides as well as sulfonates with a wide range of primary and secondary aliphatic alcohols, affording synthetically important ethers. Intramolecular C?O coupling is also possible. The reaction appears to proceed via a NiI–NiIII catalytic cycle.
- Cao, Rui,Lai, Chu-Hui,Li, Gang,Liu, Fengyi,Lu, Huan-Huan,Wang, Chao,Xiao, Jianliang,Xue, Dong,Yang, Liu,Zhang, Wei
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p. 12714 - 12719
(2020/06/02)
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- Benzo-Fused 1,4-Heterocycles via Dialkyl Carbonate Chemistry
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A novel halogen-free synthesis of benzo-fused six-membered 1,4-heterocycles through the chemistry of dialkyl carbonates is reported. Commercially available catechol, 2-aminophenol, and 2-aminothiophenol were reacted first with ethylene carbonate in an autoclave to give O -hydroxyethyl, N -hydroxyethyl, and S -hydroxyethyl derivatives respectively, through a B Al 2 mechanism. Then 2-(2-hydroxyethoxy)phenol and 2-(2-hydroxyethylamino)phenol were cyclized in excellent yields by reaction with dimethyl carbonate (DMC) and DABCO as a bicyclic organic base to give the corresponding benzodioxine and benzoxazine derivative, respectively. Moreover, 2-(2-aminophenylthio)ethanol afforded the benzothiazine derivative in good yield by reaction with DMC with an excess of a strong base such as NaH. The investigation on the cyclization reaction has highlighted that several equilibria are involved leading to the formation of carbonate and carbamate intermediates through B Ac 2 mechanisms. Depending on the reaction conditions employed, these intermediates may undergo either kinetic-controlled ring closure by a B Al 2 mechanism or by-product formation.
- Musolino, Manuele,Aricò, Fabi
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p. 1770 - 1778
(2019/04/05)
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- Revisiting Hydroxyalkylation of Phenols with Cyclic Carbonates
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Described is a tetrabutylammonium fluoride-mediated hydroxyalkylation reaction of phenols with cyclic carbonates. This operationally simple method enables the synthesis of a variety of aryl β-hydroxyethyl ethers in good to excellent yields with a very small amount of catalyst loading (0.1–1 mol%). Of particular note is the efficient conversion of aromatic diols and phloroglucinol to the corresponding bis- and tris-hydroxyethylated products. To further showcase the versatility of this protocol, guaifenesin was prepared with a single step by the condensation of guaiacol and glycerol carbonate. We also developed a flow ethoxylation process permitting the continuous synthesis of multiflorol. (Figure presented.).
- Kao, Shih-Chieh,Lin, Yi-Ching,Ryu, Ilhyong,Wu, Yen-Ku
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supporting information
p. 3639 - 3644
(2019/07/10)
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- Hydrodehalogenation of Aryl Halides through Direct Electrolysis
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A catalyst- and metal-free electrochemical hydrodehalogenation of aryl halides is disclosed. Our reaction by a flexible protocol is operated in an undivided cell equipped with an inexpensive graphite rod anode and cathode. Trialkylamines nBu3N/Et3N behave as effective reductants and hydrogen atom donors for this electrochemical reductive reaction. Various aryl and heteroaryl bromides worked effectively. The typically less reactive aryl chlorides and fluorides can also be smoothly converted. The utility of our method is demonstrated by detoxification of harmful pesticides and hydrodebromination of a dibrominated biphenyl (analogues of flame-retardants) in gram scale.
- Ke, Jie,Wang, Hongling,Zhou, Liejin,Mou, Chengli,Zhang, Jingjie,Pan, Lutai,Chi, Yonggui Robin
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supporting information
p. 6911 - 6914
(2019/05/10)
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- Iridium catalysis: Reductive conversion of glucan to xylan
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By using iridium catalysed dehydrogenative decarbonylation, we converted a partly protected cellobioside into a fully protected xylobioside. We demonstrate good yields with two different aromatic ester protecting groups. The resulting xylobioside was directly used as glycosyl donor in further synthesis of a xylooctaose.
- Pedersen, Martin J?ger,Madsen, Robert,Clausen, Mads Hartvig
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p. 952 - 955
(2018/02/07)
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- AN IMPROVED METHOD FOR THE PREPARATION OF ALKYLENEDIOXYBENZENE COMPOUNDS
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This invention relates to an improved method for preparing alkylenedioxybenzene compounds of Formula I, from the corresponding ortho-dihydroxy aromatic compound of Formula II wherein n is 0, 1, 2 or 3; and R1 and R2 independently represent H, linear or branched C1 – C10 alkyl or alkenyl group, cycloalkyl group, halogen selected from C1, Br, I, nitro (-NO2), alkoxy (-OR) or SR thioether (-SR), wherein R is linear or branched alkyl group comprising C1-C6 carbon atoms.
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Page/Page column 14
(2017/10/13)
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- Synthesis of five- and six-membered heterocycles by dimethyl carbonate with catalytic amounts of nitrogen bicyclic bases
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A catalytic amount of a nitrogen bicyclic base, i.e., DABCO, DBU or TBD, is effective for the one-pot synthesis of heterocycles from 1,4-, 1,5-diols and 1,4-bifunctional compounds via dimethyl carbonate chemistry under neat conditions. Nitrogen bicyclic bases that were previously shown to have enhanced the reactivity of DMC in methoxycarbonylation reaction by a BAc2 mechanism are herein used for the first time as efficient catalysts for cyclization reactions encompassing both BAc2 and BAl2 pathways. This synthesis procedure was also applied to a large scale synthesis of cyclic sugars, isosorbide and isomannide, starting from d-sorbitol and d-mannitol, respectively. The resulting anhydro sugar alcohols were obtained as pure crystalline compounds that did not require any further purification or crystallization. This journal is
- Aricò,Evaristo,Tundo
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p. A1176 - A1185
(2015/03/04)
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- AMIDS SUBSTITUTED INDAZOLE DERIVATIVEES AS PLOY (ADP-RIBOSE) POLYMERASE INHIBITORS
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The present invention relates to amide substituted indazoles and benzotriazoles which are inhibitors of the enzyme poly (ADP-ribose) polymerase (PARP), previously known as poly (ADP-ribose) synthase and poly (ADP-ribosyl) transferase. The compounds of the present invention are useful as mono-therapies in tumors with specific defects in DNA-repair pathways, as enhancers of certain DNA-damaging agents such as anticancer agents and radiotherapy, for reducing cell necrosis (in stroke and myocardial infarction), regulating inflammation and tissue injury, treating retroviral infections, and protecting against the toxicity of chemotherapy.
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Page/Page column 55
(2015/04/28)
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- Vinyl selenones: Annulation agents for the synthesis of six-membered benzo-1,4-heterocyclic compounds
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A novel and general approach to six-membered bicyclic benzo fused 1,4-heterocycles is described. The addition-cyclization cascade of benzo 1,2-diols, 1,2-thiols and 2-(benzylamino)phenols with stable and easily available vinyl selenones affords differently substituted 2,3-dihydro-1,4- benzodioxines, benzodithiines and 3,4-dihydro-2H-1,4-benzoxazines in good yields. The same procedure has been extended to the synthesis of 1,2,3,4-tetrahydroquinoxalines. All of these heterocycles are present in a variety of biologically active compounds.
- Bagnoli, Luana,Casini, Sara,Marini, Francesca,Santi, Claudio,Testaferri, Lorenzo
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p. 481 - 486
(2013/02/23)
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- Iridium-catalyzed dehydrogenative decarbonylation of primary alcohols with the liberation of syngas
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A new iridium-catalyzed reaction in which molecular hydrogen and carbon monoxide are cleaved from primary alcohols in the absence of any stoichiometric additives has been developed. The dehydrogenative decarbonylation was achieved with a catalyst generated in situ from [Ir(coe)2Cl]2 (coe=cyclooctene) and racemic 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (rac-BINAP) in a mesitylene solution saturated with water. A catalytic amount of lithium chloride was also added to improve the catalyst turnover. The reaction has been applied to a variety of primary alcohols and gives rise to products in good to excellent yields. Ethers, esters, imides, and aryl halides are stable under the reaction conditions, whereas olefins are partially saturated. The reaction is believed to proceed by two consecutive organometallic transformations that are catalyzed by the same iridium(I)-BINAP species. First, dehydrogenation of the primary alcohol to the corresponding aldehyde takes place, which is then followed by decarbonylation to the product with one less carbon atom.
- Olsen, Esben P. K.,Madsen, Robert
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supporting information
p. 16023 - 16029
(2013/02/22)
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- SUBSTITUTED AROMATIC CARBOXAMIDE AND UREA DERIVATIVES AS VANILLOID RECEPTOR LIGANDS
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The invention relates to substituted aromatic carboxamide and urea derivatives, to processes for the preparation thereof, to pharmaceutical compositions containing these compounds and also to the use of these compounds for preparing pharmaceutical compositions (formula (I)).
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Page/Page column 116
(2010/11/18)
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- Synthesis and spectral properties of 4-amino-and 4-acetylamino-N- arylnaphthalimides containing electron-donating groups in the N-aryl substituent
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A method for the synthesis of N-aryl-substituted 4-amino-and 4-acetylaminonaphthalimide derivatives with mono-and dialkoxy groups or a 15-crown-5 moiety in the N-aryl substituent is described. The introduction of electron-donating alkoxy groups into the benzene ring of the N-aryl fragment results in fluorescence quenching of the naphthalimide chromophore, which is most pronounced in the spectra of N-acetyl derivatives. The photophysical properties of the synthesized 4-amino-and 4-acetylaminonaphthalimides depend on the solvent polarity and its specific solvating ability due to H-bonding. The crown-containing compounds are promising fluorescent chemosensors for metal cations. ; 2009 Springer Science+Business Media, Inc.
- Panchenko,Fedorova,Perevalov,Jonusauskas,Fedorov
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scheme or table
p. 1233 - 1240
(2010/10/04)
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- Novel substituted [1,4] benzodioxino[2,3-e] isoindole derivatives, method for preparing and pharmaceutical compositions containing same
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Compounds of formula (I): wherein: A is as defined in the description, Y represents a group selected from an oxygen atom and a methylene group, R2 represents a hydrogen atom and in that case: R3 represents a group selected from a hydrogen atom and the groups linear or branched (C1-C6)alkyl, aryl, aryl-(C1-C6)alkyl (in which the alkyl moiety is linear or branched) and SO2CF3, or R2 and R3 form a bond, R1 represents a group selected from a hydrogen atom and the groups linear or branched (C1-C6)alkyl, aryl and aryl-(C1-C6)alkyl (in which the alkyl moiety is linear or branched) or a linear or branched (C1-C6)alkylene chain, Z1 and Z2 each represent a hydrogen atom or Z1 and Z2, together with the carbon atoms carrying them, form a phenyl group. Medicaments.
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Page/Page column 9
(2010/10/19)
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- One step of palladium catalyzed benzodioxane ring C-O bond formation, synthesis of isoamericanol A and isoamericanin A
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A number of benzodioxane compounds were synthesized using the palladium-catalyzed etherification of aryl halides by employing triphenylphosphane ligands. This method was used as key step in the synthesis of two natural products isoamericanol A and isoamericanin A.
- Jing, Xiaobi,Shi, Yaocheng,Liu, Yonghong,Han, Ying,Yan, Chaoguo,Wang, Li
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p. 1723 - 1727
(2007/10/03)
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- Isoquinolones
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Benzo[de]isoquinoline-1,3-dione of Formula or a pharmaceutically acceptable salt thereof wherein R is hydrogen or a protecting group typically used in the art for protecting alcohols and R1-R5are each independently chosen from H, Cl, Br, F, straight or branched alkyl C1-C8alkyl, C3-C8cycloalkyl, heterocycle or bridged heterocycle of 4-9 atoms containing 1-3 heteroatoms, —(CR′2)nOR6, —(CR′2)nN(R6)2, —(CR′2)nNR6COR7, —(CR′2)nNR6SO2OR7, —(CR′2)nNR6SO2N(R6)2, —(CR′2)nOSO2N(R6)2, —(CR′2)nCN, —(CR′2)n(NOR6)R7, NO2, CF3, —(CR′2)nSOmR7, —(CR′2)nSOmR7, —(CR′2)nCO2R6, —(CR′2)nCON(R6)2, Ph, and any two of R1-R5may form a substituted or unsubstituted ring of 5-7 total atoms having 0-2 heteroatoms are claimed which are selective inhibitors of bacterial DNA gyrase and DNA topoisomerase useful in antibacterial agents. Methods for their preparation and formulation as well as novel intermediates useful in the preparation of the final products are also claimed.
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- Quaternary ammonium salt-assisted organic reactions in water: Alkylation of phenols
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A series of quaternary ammonium salts has been tested as phase transfer agents to promote reactions between phenols and alkyl halides in an aqueous solution of sodium hydroxide in the absence of organic solvent. Methyltrioctylammonium chloride emerges as the most effective catalyst.
- Eynde,Mailleux
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- Palladium-catalyzed intramolecular C-O bond formation
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A number of oxygen heterocycles were synthesized using the palladium-catalyzed intramolecular etherification of aryl halides by employing di-tert-butylphosphinobiaryl ligands. The reaction proceeds under mild conditions using weak bases such as Cs2CO3 or K3PO4. A variety of functional groups are tolerated in the reaction, and enantioenriched alcohols can be coupled without erosion of optical purity. The mildness of the reaction conditions allows for the use of polyfunctionalized substrates. This method was used as the key step in the synthesis of MKC-242, an antidepressant currently in clinical trials. The synthesis of MKC-242 was achieved in 40% overall yield from commercially available sesamol and acrylonitrile.
- Kuwabe,Torraca,Buchwald
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p. 12202 - 12206
(2007/10/03)
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- An Improved Method for Preparing Dibenzo Crown Ethers
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In synthesis of symmetrical and unsymmetrical dibenzo crown ethers, the use of dimethyl sulfoxide as a solvent in cyclization allows an increase in the yields, a significant reduction in the reaction time, and simplification of refining.
- Kotlyar,Gorodnyuk,Grigorash,Chuprin
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p. 1135 - 1138
(2007/10/03)
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- Formation and synthetic use of oxygen-centred radicals with (diacetoxyiodo)arenes
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o-Alkyl- or o-aryl-benzenecarboxylic acids and alcohols containing an aromatic ring are treated with a (diacetoxyiodo)arene-iodine system to give the corresponding cyclized products such as phthalide, benzocoumarin and chromane derivatives in moderate to good yields via the corresponding oxygen-centred radicals. For the carboxylic acids, [bis(trifluoroacetoxy)iodo]benzene functions effectively, while (diacetoxyiodo)benzene is effective for the alcohols. Chromane and its derivatives are obtained as iodinated compounds by hypoiodite species derived from (diacetoxyiodo)benzene and iodine. Copyright 1997 by the Royal Society of Chemistry.
- Togo, Hideo,Muraki, Takahito,Hoshina, Yoichiro,Yamaguchi, Kentaro,Yokoyama, Masataka
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p. 787 - 793
(2007/10/03)
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- Remote functionalization: Cyclic alkoxylation onto aromatic ring via radical pathway
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Oxidative cyclization of alcohols containing an aromatic ring with (diacetoxyiodo)benzene and iodine gave the corresponding cyclic ethers via alkoxy radicals in good yields. The present method is very useful for the direct preparation of flavonoid and vitamin E analogues from the alcohols.
- Muraki,Togo,Yokoyama
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p. 2441 - 2444
(2007/10/03)
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- The electron spin resonance spectra of dioxene radical cations
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The electron spin resonance spectra of the radical cations of dioxene (1a), 2,3-dimethyldioxene (1b), 2,3-diphenyldioxene (1c), and benzodioxane (2) in fluid solution have been observed and analysed, with the help of ENDOR spectroscopy in the case of 1c.It is concluded that in 1c the molecule has overall C2 molecular symmetry.In all four compounds, the pseudo-axial and pseudo-equatorial protons of the methylene groups in the half-chair dioxene rings are distinguished by different hyperfine coupling constants, and simulation of the spectra over a range of temperatures has given the Arrhenius parameters for the ring inversion of 1a, 1b, and 2.Key words: ESR spectra, radical cation, 1,4-dioxene, inversion barrier.
- Davies, Alwyn G.,Shields, Charles J.,Evans, Jeffrey C.,Rowlands, Christopher C.
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p. 1748 - 1752
(2007/10/02)
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- ARYLATION OF CYCLIC ETHERS BY GASEOUS PHENYLIUM IONS. FORMATION AND BEHAVIOR OF PHENOXENIUM IONS IN THE GAS PHASE
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Free, unsolvated phenylium ions formed by the spontaneous decay of 1,4-ditritiobenzene have been allowed to react with gaseous cyclic ethers (oxirane, propene oxide, and oxetane) and acetaldehyde in the pressure range 30-250 Torr and in the presence of a thermal radical scavenger (O2, 4 Torr).The effects of a gaseous base (NMe3, 20 Torr) and of an energy moderator (He, 630-720 Torr) were also investigated.Phenylium ion confirms its considerable site selectivity, demonstrated by the distinct preference for the n-type center of the substrate, although appreciable insertion into the carbocyclic structure of propene oxide and oxetane is observed as well.The stability features of the ionic intermediates from addition of phenylium ion to selected substrates have been evaluated as well as their fragmentation and isomerization mechanisms.The behavior of gaseous phenylium ion toward cyclic ethers, in particular its ability to formally abstract an oxygen atom from the ether to give the phenoxenium ion, a reaction first observed in the present study, is discussed and compared with previous mechanistic investigations carried out in the gas phase and in solution.
- Fornarini, Simonetta,Speranza, Maurizio
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p. 2506 - 2514
(2007/10/02)
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- ARENE COMPLEXES OF TRANSITION METALS IN REACTIONS WITH NUCLEOPHILIC REAGENTS. XVII. NUCLEOPHILIC SUBSTITUTION OF THE FLUORINE ATOM BY ALKOXY GROUPS, CATALYZED BY THE (η-BENZENE)(η-ETHYLTETRAMETHYLCYCLOPENTADIENYL)RHODIUM(III) DICATION, IN THE REACTION OF FLUOROARENES WITH ALCOHOLS
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Effective catalysis by the (2+)2 complex, discovered earlier in the case of methoxydefluorination, occurs during the nucleophilic substitution of a fluorine atom by a alkoxy groups in the reactions of fluoroarenes with a wide range of alcohols in the absence of alkalis.By means of fluorobenzene it was established that the accumulation rate of the ethers depends substantially on the structure of the nucleophile and increases in the following order: PhCH2OH -CH2OH ClCH2CH2OH = sec-C3H7OH, sec-C4H9OH, cyclo-C6H11OH HO)CH2)nOH (n = 3-5) iso-C4H9OH = AlkOH (Alk = Me, Et, Pr, Bu, Am).For the case of the production of the compounds C10H21OC6H5 and C16H33O-2,4,6-Me3C6H2 it was shown that higher alkyl aryl ethers can be synthesized with yields of 65-70percent, calculated on the fluoroarene, and up to 900percent calculated on the catalyst.By the synthesis of benzodioxane in the reaction of o-fluorophenol with 2-chloroethanol it was demonstrated that heterocyclic compounds can be obtained if bifunctional substrates and reagents are used.
- Goryunov, L. I.,Litvak, V. V.,Shteingarts, V. D.
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p. 354 - 358
(2007/10/02)
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- Photolysis of the Ozonide Derived from 1,4-Benzodioxins. Synthesis of Labile o-Benzoquinones
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By the photolysis of the ozonide derived from 1,4-benzodioxins, o-benzoquinones were obtained in moderate yields independent of the stability of o-benzoquinones and of the substituent groups, except the nitro group.Through the mechanistic studies, it was indicated that o-benzoquinones were formed through a radical decomposition pathway, while catechols were formed through an ionic decomposition pathway induced by acidic impurities.
- Kashima, Choji,Tomotake, Atsushi,Omote, Yoshimori
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p. 5616 - 5621
(2007/10/02)
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- Reactions of Co-ordinated Ligands. Part 10. Rhodium-catalysed Cyclisation of 3-(2-Fluorophenyl)propanols to Chromans
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The cyclisation of several 3-(2-fluorophenyl)-propanols to the corresponding chroman occurs in nitromethane-acetone solution at 80 deg C when either the hexafluorophosphate (3) or tetrafluoroborate salt (4) of the (η5-ethyltetramethylcyclopentadienyl)(η6-benzene)rhodium(III) cation is used as a catalyst; the former salt is the more effective catalyst.The cyclisation is believed to involve the activation of the aryl fluoride (towards intramolecular nucleophilic substitution by the hydroxy group) by the formation of a metal complex in which the aryl fluoride is ?-bonded with the metal cation.It is suggested that the arene-exchange reaction which gives this ?-bonded complex proceeds faster with the salt (3) than with the salt (4), and that this is the main factor for the greater efficiency of the former salt as a cyclisation catalyst.
- Houghton, Roy P.,Voyle, Martyn,Price, Raymond
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p. 925 - 931
(2007/10/02)
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- Photodehalogenation of the Monochloro- and Monofluoroanisoles
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Evidence is presented for a plurality of mechanisms in the photoreduction and photonucleophilic substitution of the monochloroanisoles in alcohol solvents. 4-Chloroanisole appears to react partly via a radical anion and partly by radicals, while the reactions of 3-chloroanisole are more consistent with aryl cations and aryl radicals.The intermediates in the reaction of 2-chloroanisole, which gives no photosubstitution, are as yet not identified but are probably not radical anions.In the case of 4-chloroanisole, substitution and reduction may proceed from different states.Preliminary results on the fluoroanisoles show the 2-F isomer giving both reduction and substitution and the 3- and 4-F isomers only substitution.
- Siegman, John R.,Houser, John J.
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p. 2773 - 2779
(2007/10/02)
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- Ring-closure Reactions. Part 15. Solvent Effect on Cyclic Aralkyl Ether Formation by Intramolecular Williamson Synthesis
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Product analysis, rate data, and effective molarity (e.m.) values have been obtained for the formation of catechol polymethylene ethers by the intramolecular alkylation of o-ω-bromoalkoxyphenoxides in Me2SO-water (99:1,v/v).Twelve ring sizes were investigated in the range 6-32.Comparison with similar data for the reaction in EtOH-water (75:25,v/v) (except for n 32) showed the e.m. values are largely independent of solvent despite the large solvent effect observed in both the cyclization reaction and the related intermolecular model reaction.Small effects only were observed in the medium ring region.The main possible factors playing a role in solvent effects on intramolecular cyclization have been critically analysed in the light of data.
- Cort, Antonella Dalla,Illuminati, Gabriello,Mandolini, Luigi,Masci, Bernardo
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p. 1774 - 1777
(2007/10/02)
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- SYNTHESIS OF 6,7-ETHYLENEDIOXY-2,2-DIMETHYL-3-CHROMENE
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The synthesis of the title compound, a precocene analog, obtained for investigation on its biological activity, is described.
- Biernacki, Wladyslaw,Sobotka, Wieslaw
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p. 2239 - 2242
(2007/10/02)
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