- Mild electrophilic trifluoromethylation of carbon- and sulfur-centered nucleophiles by a hypervalent iodine(III)-CF3 reagent
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Inexpensive, recyclable, and activable: these are the features of a new mild electrophilic trifluoromethylation reagent that can be used to transfer a CF3 group to C-centered nucleophiles, such as β-keto esters and α-nitro esters, and to S-centered nucleophiles (see scheme). (Chemical Equation Presented).
- Kieltsch, Iris,Eisenberger, Patrick,Togni, Antonio
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- Gold oxide as a protecting group for regioselective surface chemistry
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Selective modification of electrode surfaces is a vital step in the development of many practical applications of self-assembled monolayers (SAMs). This paper describes a protection-deprotection strategy similar to that commonly utilized in organic synthesis, with gold oxide as a protecting layer, to direct self-assembly on one gold electrode in the presence of another.
- Cook, Kevin M.,Ferguson, Gregory S.
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- A simple and practical method for the oxidation of thiols to disulfides at mild conditions without solvents
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A green, straightforward, and novel method for the oxidation of thiols to the corresponding disulfides is reported using hydrogen peroxide catalyzed by tetrabutylammonium iodide (TBAI) without solvents at room temperature. The corresponding disulfides were obtained with excellent yields and short reaction times. Copyright
- He, Ying,Hang, Dongliang,Lu, Ming
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experimental part
p. 1118 - 1124
(2012/08/14)
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- Odd-even effects in charge transport across self-assembled monolayers
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This paper compares charge transport across self-assembled monolayers (SAMs) of n-alkanethiols containing odd and even numbers of methylenes. Ultraflat template-stripped silver (AgTS) surfaces support the SAMs, while top electrodes of eutectic gallium-indium (EGaIn) contact the SAMs to form metal/SAM//oxide/EGaIn junctions. The EGaIn spontaneously reacts with ambient oxygen to form a thin (~1 nm) oxide layer. This oxide layer enables EGaIn to maintain a stable, conical shape (convenient for forming microcontacts to SAMs) while retaining the ability to deform and flow upon contacting a hard surface. Conical electrodes of EGaIn conform (at least partially) to SAMs and generate high yields of working junctions. Ga2O3/EGaIn top electrodes enable the collection of statistically significant numbers of data in convenient periods of time. The observed difference in charge transport between n-alkanethiols with odd and even numbers of methylenes-the "odd-even effect"-is statistically discernible using these junctions and demonstrates that this technique is sensitive to small differences in the structure and properties of the SAM. Alkanethiols with an even number of methylenes exhibit the expected exponential decrease in current density, J, with increasing chain length, as do alkanethiols with an odd number of methylenes. This trend disappears, however, when the two data sets are analyzed together: alkanethiols with an even number of methylenes typically show higher J than homologous alkanethiols with an odd number of methylenes. The precision of the present measurements and the statistical power of the present analysis are only sufficient to identify, with statistical confidence, the difference between an odd and even number of methylenes with respect to J, but not with respect to the tunneling decay constant, β, or the pre-exponential factor, J0. This paper includes a discussion of the possible origins of the odd-even effect but does not endorse a single explanation.
- Thuo, Martin M.,Reus, William F.,Nijhuis, Christian A.,Barber, Jabulani R.,Kim, Choongik,Schulz, Michael D.,Whitesides, George M.
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supporting information; body text
p. 2962 - 2975
(2011/04/27)
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- CpMn(CO)3-catalyzed photoconversion of thiols into disulfides and dihydrogen
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The UV photolysis of CpMn(CO)3 with thiols at room temperature effected the following catalytic transformation: 2 RSH → R 2S2 + H2. This reaction is a cleaner and greener way toward making disulfides, as it produces dihydrogen as the only side-product. The manganese system exhibits high chemoselectivity as the transformation proceeds efficiently even in the presence of numerous functional groups. A manganese dicarbonyl complex, CpMn(CO)2RSH, and cyclopentadiene have also been detected using FTIR and NMR spectroscopic techniques, respectively. Based on our experimental data, a mechanism has been proposed to account for the catalysis.
- Tan, Kheng Yee Desmond,Kee, Jun Wei,Fan, Wai Yip
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experimental part
p. 4459 - 4463
(2011/01/10)
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- Preparation, structures, and physical properties of tetrakis(alkylthio) tetraselenafulvalene (TTCn-TSeF, n = 1-15)
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A series of tetrakis(alkylthio)tetraselenafulvalene compounds (TTC n-TSeF, n = 1-15) were prepared by a one-step reaction between dialkyl disulfide and tetralithiated TSeF. Molecular properties (redox potentials and optical absorptions in solution) and solid-state properties (thermal behaviors, electric conductivities, and molecular and crystal structures for n = 1 and 10) were studied. TTCn-TSeF compounds are weak electron donor molecules and characterized by small on-site Coulomb repulsion. TTC1-TSeF has a high-dimensional conduction network owing to the presence of highdimensional heteroatomic contacts, "Atomic-Wire Effect." The π-moieties of TTC10-TSeF were fastened by the alkyl chains ("Fastener Effect") to form π-columns and there are a variety of short heteroatomic contacts resulting in two dimensional electronic structure. Electrical conductivity exhibited peculiar enhancement for n = 1 and 7 ≤ n ≤ 14 owing to the presence of high-dimensional conduction paths. These compounds may manifest high carrier mobility, and are good candidates for the field-effect transistor channel based on the advantageous features: low dark conductivity, low donor ability, on-site Coulomb repulsion energy, high-dimensional π-electron structure, and high solubility in organic solvents.
- Saito, Gunzi,Yoshida, Yukihiro,Murofushi, Hidenobu,Iwasawa, Naoko,Hiramatsu, Takaaki,Otsuka, Akihiro,Yamochi, Hideki,Isa, Kimio,Mineo-Ota, Eriko,Konno, Michiko,Mori, Takehiko,Imaeda, Ken-Ichi,Inokuchi, Hiroo
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supporting information; experimental part
p. 335 - 344
(2010/07/09)
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- A mild and alternative approach towards symmetrical disulfides using H 3IO5/NaHSO3 combination
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Treatment of thiols with a mixture of periodic acid/sodium hydrogen sulfite gave the corresponding disulfides in good yield.
- Khan, Khalid M.,Taha, Muhammad,Ali, Muhammad,Perveen, Shahnaz
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experimental part
p. 319 - 320
(2010/04/23)
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- N-Phenyltriazolinedione as an efficient, selective, and reusable reagent for the oxidation of thiols to disulfides
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N-Phenyltriazolinedione is an efficient and chemoselective reagent for the oxidation of thiols to their corresponding symmetrical disulfides. The method is applicable to aromatic, aliphatic, and bi-functional thiols. The one-pot reaction takes a few minutes (in most cases studied) for completion and after a simple work-up affords the corresponding symmetrical disulfides in very good to excellent yields. Furthermore, the reaction could be performed with the same results in the absence of solvent for liquid thiols.
- Christoforou, Angelos,Nicolaou, Georgia,Elemes, Yiannis
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p. 9211 - 9213
(2007/10/03)
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- One-pot synthetic method of allyl sulfides: Samarium-induced allyl bromide mediated reduction of alkyl thiocyanates and diaryl disulfides in methanolic medium
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A convenient synthetic method of allyl sulfides by the treatment of alkyl thiocyanates or diaryl disulfides with Sm and allyl bromide in methanol has been developed.
- Zhan, Zhuang-Ping,Lang, Kai
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p. 1370 - 1371
(2007/10/03)
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- Water effects on SmI2 reductions: A novel method for the synthesis of alkyl thiols by SmI2-promoted reductions of sodium alkyl thiosulfates and alkyl thiocyanates
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Water as a cosolvent has significant improving effect on the reductivity of SmI2 in the reduction of sodium alkyl thiosulfates and alkyl thiocyanates. A new method for synthesis of alkyl thiols by SmI 2/THF/H2O system has been developed.
- Zhan, Zhuang-Ping,Lang, Kai,Liu, Feng,Hu, Li-Ming
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p. 3203 - 3208
(2007/10/03)
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- A novel reduction of sodium alkyl thiosulfates with InCl 3(cat.)/Sm(0) system in aqueous media: Facile synthesis of disulfides
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A novel reduction of sodium alkyl thiosulfates. with InCl 3(cat.)/Sm(0) system in aqueous media has been developed, which generates the corresponding disulfides in good yields.
- Li, Pinhua,Wang, Lei,Yang, Yaner,Sun, Xinhua,Wang, Min,Yan, Jincan
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p. 376 - 379
(2007/10/03)
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- Cobalt phthalocyanine mediated aerobic oxidation of thiols: A simple and convenient preparation of disulphides
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Cobalt phthalocyaninetetrasulphonamide/tetrasodium salt of cobalt tetrasulphophthalocyanine catalyzed oxidation with molecular oxygen form a simple, efficient and environmentally acceptable synthetic tool for the oxidation of thiols to disulphides in excellent yields, under mild conditions and without any side reactions.
- Venkateshwar Rao,Narasimha Rao,Jain, Suman L.,Sain, Bir
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p. 1151 - 1157
(2007/10/03)
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- A novel reduction of sodium alkyl thiosulfates using samarium metal without an activating agent in water
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A novel metallic samarium promoted reduction of sodium alkyl thiosulfates in the absence of an activating agent occurs to afford the corresponding disulfides with good yields in water at 90°C.
- Wang, Lei,Li, Pinhua,Zhou, Li
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p. 8141 - 8143
(2007/10/03)
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- Liquid-phase oxidation of thiols with chlorine dioxide
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The products and kinetics of the liquid-phase oxidation of 11 aliphatic and aromatic thiols with chlorine dioxide were studied at -10-+70 °C in organic media. The rate constants and activation parameters of the reaction were determined. The influence of the thiol structure on its reactivity was studied. A strong solvent effect on the reaction rate constant was found, and the reaction mechanism was proposed.
- Yakupov,Shereshovets,Imashev,Ismagilov
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p. 2352 - 2355
(2007/10/03)
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- Novel reductive cleavage reaction of thiobenzoates with samarium diiodide: Convenient synthesis of disulfides
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The reductive cleavage of thiobenzoates promoted by samarium diiodide afforded various kinds of disulfides in good yields under mild and neutral conditions.
- Byung Woo Yoo,Heung Soo Baek,Sam Rok Keum,Cheol Min Yoon,Ghil Soo Nam,Sung Hoon Kim,Joong Hyup Kim
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p. 4317 - 4322
(2007/10/03)
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- Alkyl- and Arylthiodediazoniations of Dry Arenediazonium o-Benzenedisulfonimides. Efficient and Safe Modifications of the Stadler and Ziegler Reactions to Prepare Alkyl Aryl and Diaryl Sulfides
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The reaction between dry arenediazonium o-benzenedisulfonimides 1 and sodium thiolates in anhydrous methanol represents an efficient and safe procedure, of general validity, for the preparation of unfunctionalized or variously functionalized alkyl aryl and diaryl sulfides. As a rule, the reaction temperature was maintained at 0-5°C for the alkylthiodediazoniations and at room temperature (20-25°C) for the arylthiodediazoniations. The sulfide yields are generally high; of the 63 considered examples, 43 gave yields greater than 80% and 13 were between 70% and 80%. Lower yields were obtained only when sterically hindered diazonium salts or thiols were used. A good amount of the o-benzenedisulfonimide (8) was always recovered from the reactions and could be reused to prepare salts 1. The copious experimental data collected in homogeneous conditions have offered several starting points for the study of the mechanism of these reactions.
- Barbero, Margherita,Degani, Iacopo,Diulgheroff, Nicola,Dughera, Stefano,Fochi, Rita,Migliaccio, Mara
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p. 5600 - 5608
(2007/10/03)
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- Water accelerated Sm/TMSCl reductive system: Debromination of vic- dibromides and reduction of sodium alkyl thiosulfates
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A simple and efficient method for the debromination of vic-dibromides to (E)-alkenes and reduction of sodium alkyl thiosulfates to disulfides promoted by Sm/TMSCl/H2O (trace) has been described.
- Xu, Xiaoliang,Lu, Ping,Zhang, Yongmin
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p. 1917 - 1925
(2007/10/03)
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- Preparation and characterization of long-chain di-n-alkyl disulfides
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The preparation of long-chain symmetric di-n-alkyl disulfides based on the reaction of BUNTE SALTS (RS2O3Na) with iodine is reported. 1H-NMR, FT-IR, and FT-RAMAN spectra of the solid and liquid/molten aliphatic title disulfides were recorded. An assignment of the vibrational frequencies is proposed especially in regard to the S-S and C-S vibrations. Distinct spectral differences are determined between the solid and liquid state, as well as between disulfides with even and those with odd numbered alkyl substituents, respectively. The observed phenomena are ascribed to different species in the solids and liquids/melts and their respective VAN DER WAALS interactions. In addition, mass spectra, GC-MS studies, as well as the thermal behaviour of the disulfides, based on investigations by DSC and TGA, are reported.
- Steinfatt, Ingeborg,Hoffmann, Gerhard G.,Brouwer, Ludwig,Menzel, Frank,Brockner, Wolfgang
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- Oxidative coupling of thiols to disulphides
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Two rapid and inexpensive procedures have been reported for the oxidative coupling of thiols to disulphides namely, sodium hypochlorite in acetonitrile and with t-butyl chloride/K2CO3 in DMF at ambient temperature.
- Khurana, Jitender M.,Singh, Sarika,Sehgal, Arti
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p. 819 - 821
(2007/10/03)
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- Preparation of disulfides by reduction of sodium alkyl thiosulfates with metallic samarium and catalytic amount of iodine
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Sm/I2 reduces sodium alkyl thiosulfates to the corresponding disulfides in good to excellent yields in THF at room temperature.
- Huang, You,Zhang, Yongmin,Wang, Yulu
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p. 1043 - 1047
(2007/10/03)
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- Preparation of dialkyl disulfides via reduction of alkylthiocyanates with TiCl4/Sm system
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Dialkyl disulfides can be readily prepared in moderate to good yields via reduction of alkylthiocyanates with TiCl4/Sm system in THF at 0°C.
- Guo, Hongyun,Zhan, Zhuangping,Zhang, Yongmin
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p. 2721 - 2724
(2007/10/03)
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- Reductive cleavage of S-S bond by samarium diiodide: A novel method for the synthesis of disulfides
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Samarium diiodide reductively cleaves the S-S bond of sodium alkyl thiosulfates to give the corresponding disulfides in moderate to good yields under mild and neutral conditions.
- Jia,Zhang,Zhou
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p. 2893 - 2898
(2007/10/02)
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- Reductive cleavage of C - S bond by samarium diiodide: A novel method for the synthesis of disulfides and thiolesters
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Disulfides were obtained by the reaction of thiocyanates with equivalent SmI2. Smarium thiolates were generated by the reaction of an equivalent of thiocyanates with two equivalents of SmI2, and then reacted smoothly with acyl chlorides to give thiolesters.
- Jia, Xueshun,Zhang, Yongmin,Zhou, Zunjun
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p. 8833 - 8834
(2007/10/02)
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- Polymer-Supported Diaryl Selenoxide and Telluroxide as Mild and Selective Oxidizing Agents
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Polystyrene-bound diaryl selenoxide and telluroxide have been prepared, which behaved as mild oxidizing agents for thiols to disulfide, phosphines to phosphine oxides, hydroquinone and catechol to p- and o-benzoquinones, and thioketones to oxo compounds.The telluroxide completed these reactions in shorter periods or under milder conditions than the selenoxide.In addition, they effected novel solvent-dependent reactions of thioamides involving thioureas to 1,2,4-thiadiazoles or to nitriles.In nonacidic solvents, the dehydrosulfurization to nitriles occured in preference to the oxidative dimerization to 1,2,4-thiadiazoles, but an acidic solvent such as acetic acid promoted the latter reaction.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 879 - 884
(2007/10/02)
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- MILD AND SELECTIVE OXIDATIONS WITH POLYSTYRENE-BOUND DIARYL SELENOXIDE
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Polystyrene-bound diaryl selenoxide is sohwn to behave as a mild oxidizing agent for thiol to disulfide, sulfide to sulfoxide, phosphine to phosphine oxide, and hydroquinone to benzoquinone.In addition, it effects solvent-dependent reactions of thioamide to nitrile in usual solvent and to thiadiazole in acetic acid.
- Hu, Nan Xing,Aso, Yoshio,Otsubo, Tetsuo,Ogura, Fumio
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p. 603 - 606
(2007/10/02)
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- Bis(p-methoxyphenyl) Selenoxide as a Mild and Selective Oxidizing Agent
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The title compound oxidized thiolsto disulfides, sulfides to sulfoxides, hydroquinone or catechol to benzoquinones, and phosphine to phosphine oxide in high yields under very mild conditions.In addition, it functioned as a useful reagent for the syntheses of 1,2,4-thiadiazole derivatives from thioureas or thioamides.
- Ogura, Fumio,Yamaguchi, Hachiro,Otsubo, Tetsuo,Tanaka, Hiroyuki
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p. 641 - 642
(2007/10/02)
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