- A Highly Chemoselective Cobalt Catalyst for the Hydrosilylation of Alkenes using Tertiary Silanes and Hydrosiloxanes
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The hydrosilylation of alkene substrates bearing additional functionalities is difficult to achieve using earth-abundant catalysts and has not been extensively realized with both earth-abundant transition metals and tertiary silanes or hydrosiloxanes. Reported herein is a well-defined bis(carbene) cobalt(I)-dinitrogen complex for the efficient, catalytic anti-Markovnikov hydrosilylation of terminal alkenes, featuring a broad substrate scope. Alkenes containing hydroxyl, amino, ester, epoxide, ketone, formyl, and nitrile groups are selectively hydrosilylated in this reaction sequence. Multinuclear NMR studies of reactive intermediates gave insights into the mechanism.
- Ibrahim, Abdulrahman D.,Entsminger, Steven W.,Zhu, Lingyang,Fout, Alison R.
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p. 3589 - 3593
(2016/07/06)
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- Silylzincation of carbon-carbon multiple bonds revisited
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The first investigation of the copper-catalyzed silylzincation of alkynes as well as a diene and styrene using bis(triorganosilyl) zinc reagents led to the development of an efficient procedure and the disclosure of an unexpected bissilylation and unfores
- Auer, Gertrud,Oestreich, Martin
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p. 311 - 313
(2008/02/08)
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- Regioselective 1,4-silylcupration of 1,3-dienes - Characterization and electrophilic trapping of the intermediate σ-allyl)copper complex
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Silylcupration reactions of 1,3-dienes with a cyanocuprate reagent PhMe2SiCuCNLi produce a (4-silyl-2-alken-1-yl)-copper complex, which was trapped by electrophiles. The use of allylic phosphates as electrophiles resulted in highly regioselecti
- Liepins, Vilnis,Baeckvall, Jan-E.
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p. 3527 - 3535
(2007/10/03)
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- Silylcupration of 1,3-dienes followed by an electrophilic trapping reaction
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(matrix presented) Silylcupration reaction of 1,3-dienes with a cyanocuprate reagent, PhMe2SiCuCNLi, followed by an electrophilic trapping has been reported for the first time. The use of allylic phosphates as electrophiles resulted in a highly
- Liepins, Vilnis,Baeckvall, Jan-E
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p. 1861 - 1864
(2007/10/03)
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- The γ-silicon effect. I. Solvent effects on the solvolyses of 2,2- dimethyl-3-(trimethylsilyl)propyl and 3-(aryldimethylsilyl)-2,2- dimethylpropyl p-toluenesulfonates
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The solvolysis rates of 2,2-dimethyl-3-(trimethylsilyl)propyl and 3- (aryldimethylsilyl)-2,2-dimethylpropyl p-toluenesulfonates were measured in a wide variety of solvents at 45 °C. The solvent effects were analyzed by using the Winstein-Grunwald equation. The solvent effects observed did not give simple linear correlations with the 2-adamantyl Y(OTs) parameter, but showed dispersion behavior in a series of binary solvents. The m values of 0.59-.67 were remarkably lower than unity for the limiting k(c) solvolysis of 2-adamantyl p-toluenesulfonate. The deviation patterns could not be interpreted in terms of nucleophilic assistance by the solvent. The dispersion behavior with reduced m values was found to be more significant for the 3-(aryldimethylsilyl) than for the 3-(trimethylsilyl) derivatives and was compatible with the delocalization of the incipient cationic charge by participation of the Si-Cγ bond in the rate-determining step. An extended dual-parameter treatment, log (k/k(80E)) = m(c)Y(OTs) + m(Δ)Y(Δ), successfully correlated such γ-silyl assisted solvolyses. The M(Δ) values of 0.24-0.49 so obtained, where M(Δ) = 0.51 m(Δ)/(m(c) +0.51 m(Δ)), are a measure of the extent of charge delocalization, suggesting that the γ-silyl group in the percaudal interaction is more effective in delocalizing the cationic charge than the alkyl group in C-C σ-participation, but less so than σ-assisted interaction by the β-aryl group.
- Nakashima, Tohru,Fujiyama, Ryoji,Fujio, Mizue,Tsuno, Yuho
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p. 741 - 750
(2007/10/03)
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- The γ-silicon effect. II. The substituent effect on the solvolysis of 3-(aryldimethylsilyl)-2,2-dimethylpropyl p-bromobenzenesulfonates
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Solvolysis rates of 3-(aryldimethylsilyl)-2,2-dimethylpropyl p- bromobenzenesulfonates were determined in 60% (v/v) aqueous ethanol (60E) and 97% (w/w) aqueous 2,2,2-trifluoroethanol (97Tw) at 50°C. The effects of aryl substituents at the silyl atom on these solvolyses were correlated with unexalted σ°parameters, giving the ρ values of -0.87 in 60E and -1.08 in 97Tw. This indicates that there exists a certain extent of positive charge on the γ-silicon atom reflecting the delocalization of incipient carbocationic charge by participation of the Si-Cγ, bond. The size of ρ values can be regarded as the effect of aryl ring on γ-Si via percaudal interaction in the rate-determining step.
- Nakashima, Tohru,Fujiyama, Ryoji,Fujio, Mizue,Tsuno, Yuho
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p. 1043 - 1047
(2007/10/03)
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- Manganese-Catalyzed Silylmagnesiation of Acetylenes and 1,3-Dienes
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The treatment of 4-benzyloxy-1-butyne with PhMe2SiMgMe in the presence of a catalytic amount of MnCl2 gave a monosilylated product, (E)-PhCH2OCH2CH2CH=CHSiMe2Ph, selectively after an aqueou
- Tang, Jun,Shinokubo, Hiroshi,Oshima, Koichiro
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p. 245 - 251
(2007/10/03)
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- ORGANIC SYNTHESIS WITH REAGENTS DERIVED FROM 3R3SiMgMe AND MnCl2
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Synthetically useful reactions mediated by reagents derived from 3 equiv. of R3SiMgMe and MnCl2 are disclosed. (1) The manganese species reacted with terminal acetylenes to give 1,2-disilylated 1-alkenes.Mono- and bis(trimethylsilyl)acetylenes gave tri- a
- Fugami, Keigo,Hibino, Jun-ichi,Nakatsukasa, Shigeki,Matsubara, Seijiro,Oshima, Koichiro,et al.
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p. 4277 - 4292
(2007/10/02)
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- SILYLMANGANATION OF 1,3-DIENES. A FACILE SYNTHESIS OF FUNCTIONALIZED VINYLSILANES
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Treatment of 1,3-dienes with (R3Si)3 MnMgMe provides silylated allylmanganese compounds which add to carbonyl moiety with high regioselectivity.
- Fugami, Keigo,Nakatsukasa, Shigeki,Oshima, Koichiro,Utimoto, Kiitiro,Nozaki, Hitosi
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p. 869 - 870
(2007/10/02)
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- SILYL-TITANATION OF ACETYLENES AND 1,3-DIENES
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A TiIII-Si active species, Cp2TiSiMe2Ph, is formed either by the reaction of Cp2TiCl2 with two equivalents of PhMe2SiLi or by the reaction of Cp2TiCl with one equivalent of PhMe2SiLi.Highly regio- and stereo-selective silyltitanation by this species has been observed with acetylenes and 1,3-dienes.
- Tamao, Kohei,Akita, Munetaka,Kanatani, Ryuichiro,Ishida, Neyoshi,Kumada, Makoto
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