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Photochemical benzylic bromination in continuous flow using BrCCl3 and its application to telescoped p-methoxybenzyl protection
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
supporting information
p. 1384 - 1388
(2019/02/14)

One-pot synthesis of 3,5-diaryl substituted-1,2,4-oxadiazoles using gem -dibromomethylarenes
1,2,4-Oxadiazole is one of the most promising heterocyclic ring systems in medicinal chemistry. In the present paper, we report the method for an efficient one-pot synthesis of 3,5-diaryl substituted 1,2,4-oxadiazoles using a two-component reaction of gem-dibromomethylarenes with amidoximes in good yields. In this method, gem-dibromomethylarenes are used as benzoic acid equivalents for the efficient synthesis of aryl-substituted 1,2,4-oxadiazoles. It is anticipated that this methodology will have versatile applications in the practical syntheses of various molecules of both medicinal and material chemistry importance.
Vinaya, Kambappa,Chandrashekara, Ganganahalli K.,Shivaramu, Prasanna D.
p. 690 - 696
(2019/09/06)

Alkyl Halides via Visible Light Mediated Dehalogenation
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.
supporting information
p. 9681 - 9687
(2019/11/28)

Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic sp 3 C-H Bonds with Potassium Bromide/Oxone at Room Temperature
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
supporting information
p. 4933 - 4939
(2018/12/14)

Copper-Catalyzed Double C(sp3)-Si Coupling of Geminal Dibromides: Ionic-to-Radical Switch in the Reaction Mechanism
A method for converting geminal dibromides into 1,1-disilylated alkanes is reported. The reaction is promoted by a copper(I) catalyst generated in situ from CuBr·SMe2 as a precatalyst and 4,4′-di-tert-butyl-2,2′-bipyridine (dtbpy) as a ligand. A Si-B reagent is used as the silicon pronucleophile. It is shown that the two C(sp3)-Si bond-forming events differ in mechanism, with the first being ionic and the second being radical.
Hazrati, Hamideh,Oestreich, Martin
supporting information
p. 5367 - 5369
(2018/09/13)

A Traceless Tether Strategy for Achieving Formal Intermolecular Hexadehydro-Diels-Alder Reactions
A synthetic strategy formally equivalent to an intermolecular hexadehydro-Diels-Alder (HDDA) reaction is described. Sulfur-based linkers were designed and constructed by joining terminal alkynes or diynes using alkyne thiolate chemistry. The resulting tetraynes and triynes successfully underwent HDDA cyclization and benzyne trapping. Linker removal by reductive desulfurization was uneventful. The strategy was also found suitable for the tetradehydro-Diels-Alder (TDDA) reaction.
Smela, Merrick Pierson,Hoye, Thomas R.
supporting information
p. 5502 - 5505
(2018/09/12)

Development of an indicator for the direct visualization of radical intermediates in organic reactions
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
supporting information
p. 11225 - 11228
(2017/10/17)

Method for preparing benzyl bromide
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.
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Paragraph 0067-0069

(2017/10/05)

Method for preparing trans-diphenylethylene compound
The invention relates to a preparation method of organic compounds and provides a method for preparing a trans-diphenylethylene compound. The method comprises adding a gem-dibromomethyl aromatic hydrocarbon compound, copper and polyamine into a reactor in the presence of a solvent, carrying out deoxidizing treatment, adding an oxygen-free water-free solvent into the reactor, carrying out a coupling reaction process to obtain C-C- double bonds, and carrying out separation and purification to obtain the trans-diphenylethylene compound. The method has mild synthesis conditions and has good reaction compatibility to different functional groups. The gem-dibromomethyl aromatic hydrocarbon compound as a raw material is easy to synthesize, may have different substituent groups and has a variable structure. The product obtained by coupling a raw material can be simply treated and has high purity. The asymmetric trans-diphenylethylene compound can be prepared from two different raw materials.
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Paragraph 0051; 0052

(2017/09/01)

E-Stilbene derivatives synthesized by stereoselective reductive coupling of benzylic gem-dibromide promoted by Cu/polyamine
Stereoselective reductive coupling reaction of benzylic gem-dibromide promoted by Cu/polyamine produces E-stilbene derivatives with high yield under mild conditions. It provides a short pathway to synthesize symmetrical and asymmetrical E-stilbene derivatives using cheap reagents and alkenyl-free starting material together with easy workup.
Cao, Hua,Wang, Qi
p. 2703 - 2706
(2017/06/23)

Regioselective Synthesis of Vinyl Halides, Vinyl Sulfones, and Alkynes: A Tandem Intermolecular Nucleophilic and Electrophilic Vinylation of Tosylhydrazones
A diazo species is trapped in an intermolecular fashion by two independent ion species in tandem at the carbene center to install an electrophile and a nucleophile on the same carbon. This metal-free concept, which is unprecedented, has been illustrated by regioselective synthesis of a variety of vinyl halides, vinyl sulfones, and alkyne derivatives. (Chemical Equation Presented).
Ojha, Devi Prasan,Prabhu, Kandikere Ramaiah
supporting information
p. 18 - 21
(2015/07/28)

Thiol-activated gem-dithiols: A new class of controllable hydrogen sulfide donors
A class of novel thiol-activated H2S donors has been developed on the basis of the gem-dithiol template. These donors release H2S in the presence of cysteine or GSH in aqueous solutions as well as in cellular environments.
Zhao, Yu,Kang, Jianming,Park, Chung-Min,Bagdon, Powell E.,Peng, Bo,Xian, Ming
supporting information
p. 4536 - 4539
(2015/01/08)

Rasta resin-triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions
Heterogeneous polymer-supported triphenylphosphine oxides based on the rasta resin architecture have been synthesized, and applied as reagent precursors in a wide range of halogenation reactions. The rasta resin-triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form halogenated products in high yields after simple purification. The polymersupported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity.
Xia, Xuanshu,Toy, Patrick H.
supporting information
p. 1397 - 1405
(2014/07/22)

Phosphorus(V)-catalyzed deoxydichlorination reactions of aldehydes
A phosphine oxide-catalyzed conversion of aldehydes into 1,1-dichlorides is reported. The reaction proceeds via a phosphorus(V)-catalysis manifold in which phosphine oxide turnover is achieved using oxalyl chloride as a consumable reagent. The new method is applicable to a range of aldehydes and, in combination with palladium-catalyzed reductive dimerization, gives rise to a new catalytic approach to the synthesis of stilbenes and a short formal synthesis of resveratrol.
An, Jie,Tang, Xiaoping,Moore, Joshua,Lewis, William,Denton, Ross M.
p. 8769 - 8776
(2013/09/23)

A sustainable two-phase procedure for V-catalyzed toluene oxidative bromination with H2O2-KBr
A sustainable V(v) and Mo(vi) catalysed two-phase procedure for bromination of toluene under quite mild conditions is proposed; H2O2 is the primary oxidant and KBr is the bromine source; metal precursors are commercially available salts. The reaction is efficient without any additional solvent. By using PhCH3 as a solvent/substrate good yields, together with interesting selectivity toward the formation of PhCH2Br, are obtained with both metal ions. Recycling of the catalytic phase is also possible. Useful information on the V-peroxido chemistry was obtained. The Royal Society of Chemistry.
Galloni, Pierluca,Mancini, Marco,Floris, Barbara,Conte, Valeria
supporting information
p. 11963 - 11970
(2013/09/02)

Green oxidation of methylarenes to benzoic acids with bromide/bromate in water
An efficient and convenient procedure has been developed for the oxidation of methylarenes to the corresponding benzoic acids using a bromide/bromate-based reagent system in water. Regeneration and reusability of the bromide/bromate reagent is demonstrated.
Patil, Rajendra D.,Bhadra, Sukalyan,Adimurthy, Subbarayappa,Ranu, Brindaban C.
scheme or table
p. 2922 - 2929
(2010/11/05)

Environmentally benign electrophilic and radical bromination 'on water': H2O2-HBr system versus N-bromosuccinimide
A H2O2-HBr system and N-bromosuccinimide in an aqueous medium were used as a 'green' approach to electrophilic and radical bromination. Several activated and less activated aromatic molecules, phenylsubstituted ketones and styrene were efficiently brominated 'on water' using both systems at ambient temperature and without an added metal or acid catalyst, whereas various non-activated toluenes were functionalized at the benzyl position in the presence of visible light as a radical activator. A comparison of reactivity and selectivity of both brominating systems reveals the H2O2-HBr system to be more reactive than NBS for benzyl bromination and for the bromination of ketones, while for electrophilic aromatic substitution of methoxy-substituted tetralone it was higher for NBS. Also, higher yields of brominated aromatics were observed when using H2O2-HBr 'on water'. Bromination of styrene reveals that not just the structure of the brominating reagent but the reaction conditions: amount of water, organic solvent, stirring rate and interface structure, play a key role in defining the outcome of bromination (dibromination vs bromohydroxylation). In addition, mild reaction conditions, a straightforward isolation procedure, inexpensive reagents and a lower environment impact make aqueous brominating methods a possible alternative to other reported brominating protocols.
Podgor?ek, Ajda,Stavber, Stojan,Zupan, Marko,Iskra, Jernej
experimental part
p. 4429 - 4439
(2009/10/09)

Visible-light-promoted Wohl-Ziegler functionalization of organic molecules with N-bromosuccinimide under solvent-free reaction conditions
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
experimental part
p. 555 - 566
(2009/09/06)

Electrochemical method for the preparation of dibromomethyl, bis(bromomethyl), and bis(dibromomethyl) arenes
Electrochemical bromination of alkyl aromatic compounds by two-phase electrolysis yields the corresponding α,α-dibrominated products. The reaction has been carried out in a single-compartment electrochemical cell using aqueous sodium bromide (40-50%), containing a catalytic amount of HBr as electrolyte, and chloroform, containing an alkyl aromatic compound, as the organic phase with a Pt plate as anode at 10-15C. Two-phase electrolysis results in high yields (70-90%) of dibromomethyl, bis(bromomethyl), and bis(dibromomethyl) arenes, depending upon the charge passed.
Kulangiappar,Karthik,Kulandainathan, M. Anbu
scheme or table
p. 2304 - 2309
(2009/12/06)

Facile conversion of aldehydes and ketones to gem-dichlorides using chlorodiphenylphosphine/N-chlorosuccinimide as a new and neutral system
Aldehydes and ketones are easily converted to their corresponding gem-dichlorides using a mixture of chlorodiphenylphosphine and N-chlorosuccinimide (ClPPh2/NCS) in dichloromethane under neutral conditions and at room temperature. Copyright Taylor & Francis Group, LLC.
Aghapour, Ghasem,Afzali, Asieh
experimental part
p. 4023 - 4035
(2009/04/11)

LEWIS ACID CATALYZED HALOGENATION OF ACTIVATED CARBON ATOMS
A practical and efficient method for halogenation of activated carbon atoms using readily available /V-haloimides and a Lewis acid catalyst has been disclosed. This methodology is applicable to a range of compounds and any halogen atom can be directly introduced to the substrate. The mild reaction conditions, easy workup procedure and simple operation make this method valuable from both an environmental and preparative point of view.
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Page/Page column 29-30

(2008/06/13)

Free radical bromination by the H2O2-HBr system on water
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
p. 7245 - 7247
(2007/10/03)

Visible light induced 'on water' benzylic bromination with N-bromosuccinimide
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
p. 1097 - 1099
(2007/10/03)

Lewis acid catalyzed highly selective halogenation of aromatic compounds
A simple and efficient procedure for the halogenation of aromatic compounds with NCS, NBS, NIS and NFSI in the presence of catalytic amount of ZrCl 4 is described. Chlorination, bromination, iodination and fluorination of various aromatic compounds are performed with high selectivity under mild reaction conditions. Georg Thieme Verlag Stuttgart.
Zhang, Yanhua,Shibatomi, Kazutaka,Yamamoto, Hisashi
p. 2837 - 2842
(2007/10/03)

Synthesis of bromoalkenes and alkylidene dibromides by reactions of carbonyl compounds with 2,4,4,6-tetrabromo-2,5-cyclohexadienone in the presence of triphenylphosphine
Reactions of aliphatic and aromatic aldehydes with the 2,4,4,6-tetrabromo-2,5-cyclohexadienone-triphenylphosphine complex result in formation of the corresponding geminal dibromides. Ketones react with the same complex to give vinyl bromides.
Matveeva,Feshin,Zefirov
p. 52 - 55
(2007/10/03)

Position 7 substituted indenyl-3-acetic acid derivatives and amides thereof for the treatment of neoplasia
In position 7 substituted indenyl-3-acetic acid derivatives and pharmaceutically acceptable salts and amides thereof have anti-neoplastic activity.
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(2008/06/13)

An Alternative Method for the Selective Bromination of Alkylbenzenes Using NaBrO3/NaHSO3 Reagent
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Kikuchi, Daisuke,Sakaguchi, Satoshi,Ishii, Yasutaka
p. 6023 - 6026
(2007/10/03)

Catalytic processes of oxidation by hydrogen peroxide in the presence of Br2 or HBr. Mechanism and synthetic applications
The mechanism and the synthetic applications for the oxidation of alcohols, ethers, and aldehydes by H2O2 catalyzed by Bf2 or Br- in a liquid two-phase system (aqueous and organic) are reported. Aliphatic and benzylic primary alcohols and ethers show an opposite behavior, which has been rationalized on the ground of the different electronic configurations of the intermediate alkyl (π-type) and acyl (σ-type) radicals and their influence on enthalpic and polar effects. A two-phase system is particularly useful also for an efficient benzylic bromination by Br2 or Br-; the substitution of the benzyl bromide by OH, OR, and OCOR regenerates Br-, which can be recycled. The evaluation of the relative reactivities of the involved substrates and intermediates has allowed to develop a variety of simple, facile, convenient, and selective syntheses of alcohols, aldehydes, ketones, esters, and benzyl bromides, which fulfill the conditions for practical applications.
Amati, Alessandro,Dosualdo, Gabriele,Zhao, Lihua,Bravo, Anna,Fontana, Francesca,Minisci, Francesco,Bjorsvik, Hans-Rene
p. 261 - 269
(2013/09/08)

Synthesis and application of new phenyl-functionalized zeolites as protection against radical bromination at the benzylic position
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
p. 1450 - 1452
(2007/10/03)

Lanthanide complexes of a new tetradentate nitrogen donor and their applications in organic synthesis
Isatoic anhydride reacts with propylenediamine to form N,N′-propylene-bis-(2-aminobenzamide) [PBAB]. The reaction between PBAB and lanthanide chlorides (Lanthanides=La, Ce, Pr, Sm, Eu, Dy, Yb, Lu) yields 1 : 1 complexes. The ligand PBAB and the complexes have been characterised by elemental analyses, IR, 1H NMR, electronic spectral, magnetic, conductance and thermal studies. The complexes are found to catalyse the bromination of arenes by molecular bromine stereospecifically.
Swamy,Kumar
p. 489 - 493
(2007/10/03)

HALOQUASIPHOSPHONIUM SALTS IN REACTIONS WITH ALDEHYDES
Quasiphosphonium salts with a P-Br bond, prepared from tris( fluoroalkyl ) phosphites and bromine, readily react with benzaldehyde, propanal, and DMF via a dihalodeoxygenation route.Reaction of tris(2,2,2-trifluoroethoxy)bromophosphonium bromide with chloral yields bis(2,2,2-trifluoroethyl) 1-bromo-2,2,2-trichloroethyl phosphate and 2,2,2-trifluoroethyl bromide.The ability of bromophosphonium salts to form with chloral only phosphates was used for studying intermediate products in the reaction of tris(2,2,2-trifluoroethyl) phosphite with cyanogen bromide in the presence of chloral.The reaction proceeds by the halogenophilic mechanism.
Mironov, V. F.,Konovalova, I. V.,Burnaeva, L. M.
p. 351 - 355
(2007/10/03)

Photothermal Side-Chain Bromination of Methyl-, Dimethyl-, and Trimethylbenzenes with N-Bromosuccinimide
Tri- and dibromination of methyl-, dimethyl-, and trimethylbenzenes with N-bromosuccinimide were accomplished by photothermal reaction with a tungsten lamp in carbon tetrachloride or benzene. (Dibromomethyl)arenes and (tribromomethyl) derivatives were produced depending upon a solvent used and a substituent on the benzene ring.In the bromination of methylbenzenes without a substituent on the ortho-position, (tribromomethyl)benzenes were formed.On the other hand, ortho-substituted methylbenzenes gave (dibromomethyl)benzenes. α,β-Dibromo-1,2-diarylstilbenes were formed via the debrominative carbon-carbon coupling reaction of ...
Mataka, Shuntaro,Liu, Guo-Bin,Sawada, Tsuyoshi,Kurisu, Masayoshi,Tashiro, Masashi
p. 1113 - 1119
(2007/10/02)

Substituted dibenz-oxa-thiocinones, -12-oxides and -12,12-dioxides, a process for their preparation and their use in medicaments
The invention relates to substituted dibenz-oxa-thiocinone-12-oxides and -12,12-dioxides of the general formula I STR1 in which R1 to R6 and Y have the meaning indicated in the description, to processes for their preparation and to their use in medicaments, in particular in circulation-influencing medicaments.
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(2008/06/13)

UNSTABLE 2,2-DIBROMO-2-ETHOXY-4,5-BENZO-1,3,2-DIOXAPHOSPHOLANE IN ADDITION REACTIONS TO CHLORAL AND BENZALDEHYDE
2,2-Dibromo-2-ethoxy-4,5-benzo-1,3,2-dioxaphospholane (I) adds to chloral with no change in the phosphorus coordination.In contrast to chloral, benzaldehyde is converted to dibromotoluene upon reaction with (I).
Mironov, V. F.,Ofitserov, E. N.,Konovalova, I. V.,Pudovik, A. N.
p. 1475 - 1477
(2007/10/02)

One pot synthesis of substituted tropones from 7,7-Dihalo-2,3-(or 3,4-)epoxybicyclo[4.1.0]heptane Derivatives
In order to obtain a scope and limitations of the reaction for newly developed tropone synthesis, some substituted 2,3- and 3,4-epoxy-7,7-dihalobicyclo[4.1.0]heptanes have been prepared and treated with several acids. We found that (1) the epoxy-carbons of starting materials should have, at least, one substituent which may stabilize the carbenium ion formed by cleavage of the epoxide with acid, (2) as halogens in the starting materials, bromine is superior to chlorine, (3) use of 20 molar equivalent of TFA to a substrate in chloroform at refluxing temperature or use of each 5 molar equivalent of TCA and water to a substrate in toluene at 100 °C is recommended.
Kato,Yamamoto,Nomura,Miwa
p. 64 - 73
(2007/10/02)

2,2-DIBROMO-2-(2,2,3,3-TETRAFLUOROPROPOXY)BENZO-1,3,2λ5-DIOXAPHOSPHOLE - A NEW BROMINATING REAGENT
A new reagent 2,2-dibromo-2-(2,2,3,3-tetrafluoropropoxy)benzo-1,3,2λ5-dioxaphosphole is proposed for the synthesis of gem-dibromides from aldehydes.It was established that the concurrent reaction of chloral and propanal with this phosphole results in the exclusive formation of 1,1-dibromopropane; this favors the idea that the aldehyde acts as a nucleophilic particle in the rate-determining stage.
Mironov, V. F.,Ofitserov, E. N.,Sinyashina, T. N.,Konovalova, I. V.
p. 2228 - 2230
(2007/10/02)

Conversion of Aldehydes into 1,1-Dibromoalkanes
Aliphatic and aromatic aldehydes have been converted into 1,1-dibromoalkyl derivatives using a 1:1 mixture of triphenyl phosphite and bromine as reagent.
Hoffmann, R. W.,Bovicelli, P.
p. 657 - 659
(2007/10/02)

Benzylic Bromination-Acetoxylation of Toluenes by Bromide Ion Catalyzed Thermal Decomposition of Peroxydisulfate in Acetic Acid in the Presence of Acetate Ions
Side-chain bromination and acetoxylation of alkylaromatics by halide ion induced decomposition of potassium peroxydisulfate in acetic acid have been studied by product analysis techniques.Catalytic amounts of lithium bromide in the presence of sodium acetate were found effective in promoting benzylic bromination, followed by conversion to the corresponding benzyl acetates by reaction with acetate.The reaction is interpreted to take place by the redox and free-radical chain mechanism involving bromine atoms (ρ = -1.38 vs. ? + for substituted toluenes).In competiti ve experiments, benzyl and 4-nitrobenzyl acetates were found lees reactive than the corresponding toluenes in acetic acid with the couple S2O82-/Br- but more reactive in carbon tetrachloride with N-bromosuccinimide.
Citterio, Attilio,Santi, Roberto,Pagani, Anselmo
p. 4925 - 4927
(2007/10/02)

MECHANISMS OF FREE-RADICAL REACTIONS. XX. REACTIVITY IN THE FREE-RADICAL HALOGENATION REACTIONS OF ARYLFLUOROALKANES
The free-radical chlorination and bromination of meta- and para-substituted benzyl fluorides and 1,1-difluoro-2-phenylethane and also the chlorination of 1-fluoro-2-arylethanes by phenylchloroiodonium chloride and the bromination of meta- and para-substituted benzyl bromides were studied by the method of competing reactions.In all cases a good correlation is observed between log krel and the Brown ?+ constants.In cases where change in the reactivity in the transition from one reaction series to another is due mainly to the polar effect of the substituent whilethe selectivity is measured in relation to the polar effect direct relationships are observed between the reactivity and the selectivity.
Dneprovskii, A. S.,Eliseenkov, E. V.
p. 711 - 719
(2007/10/02)

THE REACTION OF ETHANEDIYL S,S-ACETALS WITH HALOGENES
Cyclic thioacetals and thioketals (1,3-dithiolanes) are reported to react smoothly with halogens in a 1:1 molar ratio, at room temperature in anhydrous carbon tetrachloride.The mechanistic aspects of the reaction are considered and evidence is shown of the itermediacy of monocationic rather than the previously postulated dicatonic species in the cleavage reactions of 1,3-dithiolanes of aromatic ketones.
Caputo, Romualdo,Ferreri, Carla,Palumbo, Giovanni,Capozzi, Giuseppe
p. 2369 - 2376
(2007/10/02)

THE BROMINATION OF METHYLARENES WITH NBS BY IRRADIATION USING A TUNGSTEN LAMP. PREPARATION OF BENZOTRIBROMIDES
Bromination of toluene and its meta- and para-substituted derivatives with NBS by irradiation using a tungsten lamp gave benzotribromides and cis- and trans-1,2-dibromo-1,2-diaryl-ethylenes, while ortho-substituted toluenes gave benzal bromides. o-Xylene gave tetra- and pentabromides and m-xylene afforded a mixture of dibromodiarylethylenes.
Mataka, Shuntaro,Kurisu, Masayoshi,Takahashi, Kazufumi,Tashiro, Masashi
p. 1969 - 1972
(2007/10/02)

Dibromocarbonyl Ylides. Deoxygenation of Aldehydes and Ketones by Dibromocarbene
The reaction of phenyl(tribromomethyl)mercury (4) with benzaldehyde-α-13C results in benzal-α-13C bromide and CO.The generality of this deoxygenation was shown by treatment of other aldehydes and ketones with mercurial 4 (1.8:1, benzene, 80 deg C, 4 h): , Ph (46), Et (35), i-Pr (39), t-Bu (19); Ph, Ph (6), Ph, Me (15), Me, Me (16), Et, n-Bu (19), Me, c-C3H5 (20), c-C3H5, c-C3H5 (20), cyclohexanone (38), cyclopentanone (19), norcamphor (46).Additional products in selected cases include (for acetophenone) α-bromostyrene, (for cyclohexanone) 1-bromocyclohexene and 1,1-dibromocyclohexane, (for norcamphor) 2,2-dibromonorbornane, 1,2-dibromonorbornane, 2-bromo-2-norbornene and 1-bromonorbornene, and (for pivaldehyde) 1,1-dibromo-2,2-dimethylpropane.The yields of CO from the treatment of a series of benzaldehydes with mercurial 4 (1.8:1 benzene, 80 deg C, 20 h) are given in parentheses: ArCHO (percent CO), 4-MeO (81), 4-Me (61), 3-Me (55), H (50), 4-F (46), 3-MeO (58), 4-Cl (46), 4-Br (47), 3-Cl (34), 3,4-Cl2 (27).A Hammett-type correlation of log (yield)/(yield)0 vs. ? gave ρ = -0.50 (r = 0.94).
Huan, Zhenwei,Landgrebe, John A.,Peterson, Kimberly
p. 4519 - 4523
(2007/10/02)

N-Bromosaccharin: Benzylic and α-Carbonylic Bromination
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Sanchez, Eduardo I.,Fumarola, Martin J.
p. 1588 - 1590
(2007/10/02)

The easy preparation of many benzylic bromides using molecular bromine as a halogenating in the presence of catalytic amounts of lanthanum tri-acetate
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.
p. 327 - 328
(2007/10/02)

OXYGEN-BROMINE EXCHANGE BETWEEN AROMATIC ALDEHYDES AND ARYLDIBROMOMETHANES
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Litvinenko, G. S.,Dvorko, G. F.,Maksimenko, N. M.
p. 2220 - 2222
(2007/10/02)

Reactions of Carbonyl Compounds with Tervalent Phosphorus Reagents. Part 12. Aromatic Aldehydes with Bromophosphines and Phosphorus Tri-iodide
The reactions of aromatic aldehydes with phosphorus tribromide (4a), with phosphorus tri-iodide (3), and with bromodiphenylphosphine (4b) have been investigated in detail.Both the trihalides react as electrophiles to produce high yields of the appropriate benzylidene dihalide.Thereafter, these reactions differ from each other and from that of phosphorus trichloride.Bromodiphenylphosphine (4b) reacts in biphilic fashion to produce (α-bromobenzyl)diphenylphosphine oxide (15).This oxide is readily dehalogenated under the reaction conditions and in model studies.Cyanodiphenylphosphine is unreactive towards benzaldehyde.These halogenophosphine reactions confirm the generality of the trends first observed with chlorophosphines and that the nature of the other two ligands on phosphorus determines the mode of reaction with aldehydes.
Michie, Jacqui,Miller, J. Allen,Nunn, M. John,Stewart, Denis
p. 1744 - 1749
(2007/10/02)

Substituted amino acids
Esters and thiolesters of amino acids, intermediates therefor, synthesis thereof, and the use of said esters and thiolesters and compositions for the control of pests.
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(2008/06/13)

Indenylacetic acid compounds
4, 5, 6 or 7 Aryl substituted indenyl acetic acids and pharmaceutically acceptable salts, amides and esters thereof. The 4, 5, 6 or 7 aryl substituted indenyl acetic acids have anti-inflammatory, anti-pyretic and analgesic activity. The invention also includes methods for the preparation of these compounds, pharmaceutical compositions and methods of treating inflammation by administering these particular compounds to patients.
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(2008/06/13)