- Dehydrogenative Sn–E (E?=?S, Se) bond formation catalyzed by an iron complex
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Iron complex-catalyzed dehydrogenative Sn–E (E?=?S, Se) bond formation of hydrostannane with thiol and selenol was achieved. All new compounds were fully characterized using 1H, 13C{1H}, 77Se{1H}, and 119Sn{1H} NMR measurements and elemental analyses. The structure of 1,1′-(1,3-dithia-2,2-dibutylstanyl)-[3]ferrocenophane was confirmed by single-crystal X-ray diffraction.
- Itazaki, Masumi,Ogawa, Yudai,Nakamura, Wataru,Nakazawa, Hiroshi
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- Polarity-reversal-catalyzed hydrostannylation reactions: Benzeneselenol-mediated homolytic hydrostannylation of electron-rich olefins
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Addition of 10 mol-% of diphenyl diselenide to hydrostannylation reactions involving electron-rich olefins results in a dramatic improvement in yield. For example, reaction of α-([(tert-butyl)dimethylsilyl]-oxy}styrene (1) with triphenylstannane (2a; 1.1
- Ford, Leigh,Wille, Uta,Schiesser, Carl H.
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p. 2306 - 2311
(2007/10/03)
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- Flash photolysis investigation of the reaction of phenylselanyl radicals with hexabutyldistannane
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The reaction of the phenylselanyl radical with hexabutyldistannane was studied by flash photolysis and the rate constants and activation parameters were determined.
- Beletskaya, Irina P.,Sigeev, Alexander S.,Kuzmin, Vladimir A.,Tatikolov, Alexander S.,Hevesi, Laszlo
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p. 107 - 109
(2007/10/03)
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- Diverging effects of steric congestion on the reaction of tributylstannyl radicals with areneselenols and aryl bromides and their mechanistic implications
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The effects of bulky ortho,ortho' groups on the reactions of aryl bromides and areneselenols with tributylstannane have been studied. Bulky ortho,ortho' groups accelerate the reaction of the bromides with the stannane but retard the reactions of the selenols. On the other hand, ab initio and force field calculations show that introducing bulky ortho substituents into selenols causes a greater increase in strain than in the corresponding bromides. Two possible explanations for the divergent reactivity patterns are advanced. On one hand, it is possible that bromine abstraction by stannyl radicals from aryl bromides proceeds in a single step through a linear transition state whereas the abstraction of sell from the selenols involves a T-shaped, hypervalent intermediate. Alternatively, it may be that both reactions are concerted with the bromine abstraction having a late transition state and the sell abstraction an early one. Approximate second-order rate constants for the reaction of tributylstannane with a range of hindered aryl bromides are derived from competition reactions. 2,4,6-Tri-tert- butylbenzeneselenol is able to function moderately well as a catalyst for the stannane-mediated reactions of vinyl bromides. The X-ray crystal structure of bis(2,4,6-triisopropylphenyl) diselenide is presented.
- Crich, David,Hwang, Jae-Taeg,Gastaldi, Stephane,Recupero, Francesco,Wink, Donald J.
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p. 2877 - 2882
(2007/10/03)
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- Reversibility in free-radical reactions of aryltellurides with tributylstannyl, tributylgermyl and tris(trimethylsilyl)silyl radicals
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1H, 13C, 29Si, 77Se, 119Sn and 125Te NMR spectroscopies reveal that methyl, primary and secondary alkyl radicals, generated through the reaction of aryltelluroalkanes (4-9) with tributyltin hydride, tributylgermanium hydride or tris(trimethylsilyl)silane) under standard radical conditions (benzene, AIBN) are capable of displacing tributylstannyl, tributylgermyl and tris(trimethylsilyl)silyl radicals from aryltellurotributylstannanes (1, 2), aryltellurotributylgermanes (10, 11) and aryltellurotris(trimethylsilyl)silanes (13, 14) respectively. These observations are in agreement with high-level ab initio molecular orbital studies. Calculations using a (valence) double-ζ pseudopotential basis set supplemented with polarization functions and with the inclusion of electron correlation (MP2/DZP) predict energy barriers for the displacement of stannyl (SnH3), germyl (GeH3) and trisilylsilyl ((H3Si)3)Si) radicals by methyl, ethyl and iso-propyl radicals to lie between 22 and 39 kJ mol-1, with reverse barriers of between 12 and 40 kJ mol-1. Consequently, the use of aryltellurides as alkyl radical precursors together with (standard) chain-carrying reagents such as tributyltin hydride, tributylgermanium hydride and tris(trimethylsilyl)silane may be complicated with equilibria which may result in diminished reaction yields.
- Schiesser, Carl H.,Skidmore, Melissa A.
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p. 145 - 157
(2007/10/03)
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- Vinyl Anion Equivalents. Part IV. Efficient Synthesis of 2-(1-Hydroxyalkyl)-2-cyclopenten-1-ones
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Aldol reactions of lithium enolates resulted from conjugate additions of tributylstannyllithium to 2-(phenylseleno)-2-cyclopenten-1-one provides 2-(1-hydroxyalkyl)-2-cyclopenten-1-ones in high yields.Significantly good 1, 4-asymmetric induction took place
- Kusuda, Shinya,Ueno, Yoshio,Toru, Takeshi
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p. 2720 - 2724
(2007/10/02)
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- REACTIVITY OF ALLYLIC AND VINYLIC SILANES, GERMANES, STANNANES AND PLUMBANES TOWARD SH2' OR SH2 SUBSTITUTION BY CARBON- OR HETEROATOM-CENTERED FREE RADICALS
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Compounds of the type CH2=CHCH2MR3 and (E)-PhCH=CHMR3 (M = Si, Ge, Sn, Pb) were allowed to react with a series of heteroatom-centered radicals (PhY*, Y = S, Se, Te, derived from PhYYPh) and carbon-centered radicals ((CH3)2CH* derived from (CH3)2CHHgCl).We report that alkenylplumbanes and, under forcing conditions, alkenylgermanes undergo SH2 or SH2' substitution of the metal by chain mechanism analogous to those previously reported for alkenylstannanes.Alkenylsilanes are unreactive.Based solely upon product yields, the following trends were observed: The reactivity of the alkenylmetals follow the order metal = Pb > Sn > Ge (> Si).The allylmetals were more reactive then the β-metallostyrenes toward the reactants employed in this study.The chalcogen series PhYYPh exhibits the reactivity order Y = S > Se > Te.
- Light, James P.,Ridenour, Michael,Beard, Lois,Hershberger, James W.
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