- A highly efficient heterogeneous ruthenium(III)-catalyzed reaction of diaryl diselenides with alkyl halides leading to unsymmetrical diorganyl selenides
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A highly efficient heterogeneous ruthenium(III)-catalyzed reaction of diaryl diselenides with alkyl halides was achieved in DMF at 100?°C in the presence of 2?mol% of an MCM-41-immobilized bidentate nitrogen ruthenium(III) complex [MCM-41-2N-RuCl3] and zinc, yielding a variety of unsymmetrical diorganyl selenides in good to excellent yields. This new heterogeneous ruthenium catalyst can easily be prepared via a simple two-step procedure from commercially readily available and inexpensive reagents, and recovered by filtration of the reaction solution and recycled for at least eight times without a significant loss of activity.
- Chen, Qiurong,Wang, Pingping,Yan, Tao,Cai, Mingzhong
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- Ionic liquid/PPh3 promoted cleavage of diphenyl disulfide and diselenide: A straight-forward metal-free one-pot route to the synthesis of unsymmetrical sulfides and selenides
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A metal-free cleavage of diphenyl disulfide and diphenyl diselenide has been achieved using ionic liquid/triphenyl phosphine (PPh3) and a convenient protocol for the one-pot synthesis of unsymmetrical sulfides and selenides by condensing 'in situ' generated thiolate or selenate anion with alkyl halides has been developed. In addition, 1,4-conjugate addition of the generated thiolate anions to activated alkenes has also been demonstrated. The ionic liquid, 1-methyl-3-pentyl imidazolium bromide, [pmIm]Br plays a crucial role in promoting the course of the reactions and shows superior activity and selectivity compared to other solvents. The [pmIm]Br has been reused for at least five times without appreciable loss of activity.
- Banerjee, Subhash,Adak, Laksmikanta,Ranu, Brindaban C.
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supporting information; experimental part
p. 2149 - 2152
(2012/05/05)
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- Convenient synthesis of unsymmetrical organochalcogenides using organoboronic acids with dichalcogenides via cleavage of the S-S, Se-Se, or Te-Te bond by a copper catalyst
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(Chemical Equation Presented) This article describes the methodology for a copper-catalyzed preparation of numerous monochalcogenides from dichalcogenides with organoboronic acids. Unsymmetrical diorgano-monosulfides, selenides, and tellurides can be synthesized by the coupling of dichalcogenides with aryl- or alkylboronic acids using a copper catalyst in air. The present reaction can take advantage of both organochalcogenide groups on dichalcogenide.
- Taniguchi, Nobukazu
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p. 1241 - 1245
(2007/10/03)
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- Indium(I) iodide-promoted cleavage of diaryl diselenides and disulfides and subsequent condensation with alkyl or acyl halides. One-pot efficient synthesis of diorganyl selenides, sulfides, selenoesters, and thioesters
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Diphenyl diselenides and disulfides undergo facile cleavages by indium(I) iodide and the corresponding generated selenate and thiolate anions condense in situ with alkyl or acyl halides present in the reaction mixture. Thus, a simple, efficient, and general procedure has been developed for the synthesis of unsymmetrical diorganyl selenides, sulfides (thioethers), selenoesters, and thioesters by this one-pot reaction at room temperature.
- Ranu, Brindaban C.,Mandal, Tanmay
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p. 5793 - 5795
(2007/10/03)
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- Indium(I) iodide-mediated cleavage of diphenyl diselenide. An efficient one-pot procedure for the synthesis of unsymmetrical diorganyl selenides
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(Matrix presented) A simple and efficient procedure has been developed for the synthesis of unsymmetrical diorganyl selenides through a one-pot indium(I) iodide-mediated reaction of alkyl halide and diphenyl diselenide in methylene chloride at room temperature.
- Ranu, Brindaban C.,Mandal, Tanmay,Samanta, Sampak
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p. 1439 - 1441
(2007/10/03)
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- Intramolecular assistance of electron transfer from heteroatom compounds. Electrochemical oxidation of 2-(2-pyridyl)ethyl-substituted ethers, sulfides, and selenides
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Organoheteroatom compounds having a 2-(2-pyridyl)ethyl group were synthesized and their oxidation potentials were determined by rotating disk electrode voltammetry. The oxidation potentials were found to be less positive than those of the corresponding compounds having a phenyl group in place of the pyridyl group. The dynamic coordination of the pyridyl group to the heteroatom, which stabilizes the cation radical intermediate, seems to be responsible for facilitating the electron transfer. The magnitude of the intramolecular assistance increases along with an increase in the oxidation potential of the parent compounds. This tendency can be explained in terms of the energy match between the nonbonding p orbital of the pyridyl nitrogen and the HOMO of the parent heteroatom compound.
- Watanabe, Mitsuru,Suga, Seiji,Yoshida, Jun-Ichi
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p. 243 - 247
(2007/10/03)
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- Preparation of 2-alkylselenobenzothiazoles by the reaction of alcohols with 2-(2-oxoethylseleno)benzothiazoles in the presence of tertiary phosphines
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Reactions of alcohols with 2-(1,2-diphenyl-2- oxoethylseleno)benzothiazole in the presence of Bu3P gave the corresponding 2-alkylselenobenzothiazoles, where inversion of the secondary carbinol center of the alcohols took place. 1,3-Butanediol reacted at the primary hydroxyl group, while 1-phenyl-1,2-ethanediol reacted at the secondary hydroxyl group.
- Shibata, Koichi,Yamaga, Hiko,Mitsunobu, Oyo
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p. 947 - 966
(2007/10/03)
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- On The Reactions of Benzeneseleninic Anhydride With Monosubstituted Hydrazones. Evidence for Radical Pathways.
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The known oxidation of mono-substituted hydrazones by benzeneseleninic anhydride has been studied using 77Se and 13C NMR spectroscopy.The intermediates in the reaction have been identified.Good evidence that certain steps in these reactions are radical in character has been secured.
- Barton, Derek H. R.,Okano, Takashi,Parekh, Shyamal I.
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p. 1823 - 1836
(2007/10/02)
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- Free Radical Reactions in Synthesis. Homolysis of Alkylcobalt Complexes in the Presence of Radical-Trapping Agents
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Irradiations of the alkylcobalt salophen complexes (14), (21), (22), and (23) in the presence of radical-trapping agents, e.g. molecular oxygen, tetramethylpiperidine oxide, nitrogen monoxide, diphenyl disulphide, diphenyl diselenide, methanesulphonyl chloride, bromotrichloromethane, or iodine, leads to oxygen- , nitrogen- , sulphur/selenium- or halogen- (34) functionalised products.When these radical-trapping methodologies are combined with cobalt-mediated radical cyclisation reactions (Scheme 2) a powerful synthetic procedure, i.e. radical carbon-to-carbon bond formation with simultaneous functionalisation of the product radical centre, becomes available.
- Patel, Vinod F.,Pattenden, Gerald
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p. 2703 - 2708
(2007/10/02)
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- RADICAL C-Se BOND CLEVAVAGE OF SELENONIUM SALTS WITH GRIGNARD REAGENTS OR MAGNESIUM METAL
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The reaction of 2-methylisoselenochromanium salt with Grignard reagents afforded the reductive ring-opened product by the single electron transfer (SET) mechanizm, not by the self-decomposition of ?-selenurane.The same reduction was observed in the reaction of the selenonium salt with magnesium metal.Some other selenonium salts were easily reduced by magnesium metal to give ring-opened products.
- Hori, Mikio,Kataoka, Tadashi,Shimizu, Hiroshi,Tsutsumi, Kazuhiro
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p. 981 - 984
(2007/10/02)
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- Oxidation of Alkyl Phenyl Selenides, Tellurides, and Telluroxides with meta-Chloroperbenzoic Acid for a Facile and Novel Transformation of C-Se and C-Te Bonds to C-O Bonds
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In sharp contrast to the well-known selenoxide elimination leading to olefins, the treatment of alkyl phenyl selenides (PhSeR) with an excess of meta-chloroperbenzoic acid (MCPBA; 2-5 equiv. to a selenide) in alcohol at room temperature affords the corresponding dialkyl ethers by the substitution of a phenylselenium (PhSe) moiety with an alkoxy group.A similar reaction proceeds by using alkyl phenyl tellurides (PhTeR) and telluroxides , a facile substitution of PhTe or PhTe(O) moiety by an alkoxy group being observed.Methanol is the most appropriate solvent for these oxidations and alkyl methyl ethers are formed in excellent yields.The reaction is accompanied by phenyl migration when applied to some selenides, tellurides, and telluroxides having a phenyl group at a vicinal position to the PhSe, PhTe, or PhTe(O) moiety.Application to the methoxyselenation and methoxytelluration products of cyclohexene and cycloheptene results in a ring-contraction to afford the dimethyl acetals of cyclopentane- and cyclohexane-carbaldehyde, respectively.In case of an allylic phenyl selenide, a sigmatropic rearrangement giving a rearranged allylic alcohol occurs in much preference to the substitution by the methoxy group.Other oxidizing agents than MCPBA such as NaIO4, H2O2, t-BuOOH, and ozone are generally ineffective under similar conditions.It is proposed that the reaction mainly takes place as follows.Alkyl phenyl selenone, alkyl phenyl tellurone, or the MCPBA addition product to them is formed as a reactive intermediate in which an alkyl C-Se or alkyl C-Te bond fission occurs heterolytically by a nucleophilic attack of alcohol, sometimes accompanied by a 1,2-shift of the β-substituent, i.e., phenyl migration and ring-contraction.
- Uemura, Sakae,Fukuzawa, Shin-ichi
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p. 471 - 480
(2007/10/02)
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- Flash Pyrolysis of Selenides. Syntheses of Bibenzyls, Olefins, and Related Compounds
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Pyrolyses of a series of selenides and diselenides were studied. Selenides and diselenides bound with an active methylene group like benzyl gave a variety of substituted bibenzyls and related ethane derivatives in high yields. Other diselenides were easily caused to cleave to give various aromatic and aliphatic olefins in good yields together with elemental selenium. Lepidopterene, paracyclophane, and benzocyclobutene were prepared by thermal cleavage of their corresponding phenylselenomethyl-substituted compounds as an application of the pyrolysis concerned.
- Higuchi, Hiroyuki,Otsubo, Tetsuo,Ogura, Fumio,Yamaguchi, Hachiro,Sakata, Yoshiteru,Misumi, Soichi
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p. 182 - 187
(2007/10/02)
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