2295-05-8Relevant academic research and scientific papers
Mechanisms of Hydride Abstraction from Organometallic Compounds. Effects of Two β-Metal Substituents on the Kinetics of Dehydrometalation
Traylor, T.G.,Koermer, G.S.
, p. 3651 - 3657 (1981)
A series of 1,3-dimetallopropanes, Me3M(CH2)3M'Me3, in which M and M' are C, Si, Ge, Sn, and Pb, has been reacted with triphenylcarbenium ion to remove hydride and yield triphenylmethane.The rate constants for these reactions follow the Hammett-type relationship log k2 = ρΣ?+ + constant, where Σ?+ is the sum of ?+CH2MPh3 for both metal groups.This relationship leads to the conclusion that both metal groups simultaneously stabilize a carbocation intermediate by vertical stabilization through ?-? conjugation.
Catalytic transformations of oligocarbosilanes induced by AlCl3
Chernyavskaya,Aleksinskaya,Zavin,Belokon'
, p. 2147 - 2148 (1997)
Catalytic activation of Si - C bonds in poly(vinyltrimethylsilane) was studied using a model reaction of catalytic transformations of oligocarbosilanes Me3Si(CH2)nSiMe3 (n = 2, 3) in dichlorodimethylsilane in the presence of AlCl3 as an example. The formation of ClMe2Si(CH2)nSiMe3 was established by chromato-mass spectrometry and GLC.
Hydrogenation of silyl-substituted alkynes using diimide: Application to the synthesis of saturated sila-macrocycles
Kwon, Eunsang,Sakamoto, Kenkichi,Kabuto, Chizuko,Kira, Mitsuo
, p. 1416 - 1417 (2007/10/03)
The hydrogenation of bistrimethylsilylactylene, bis(trimethylsilyl)-1,3-diynes, and related silylalkynes giving the corresponding saturated compounds were achieved by using diimide prepared in situ from p-toluenesulfonyl hydrazide in diglyme. The present
On the mechanism of metal colloid catalyzed hydrosilylation: Proposed explanations for electronic effects and oxygen cocatalysis
Lewis, Larry N.
, p. 5998 - 6004 (2007/10/02)
Several aspects of the platinum-catalyzed hydrosilylation reaction, R3SiH + R′CH=CH2, are described and a mechanism based on the intermediacy of colloids is proposed. New features of this mechanism include (1) formation of a Pt colloid/R3SiH intermediate 2 from the reaction of the Pt colloid 1 and R3SiH, (2) consideration of the olefin as a nucleophile and thus intermediate 2 being an electrophile in this reaction, (3) hydrosilylation dependence on cocatalysis by dioxygen where no O-O bond breakage occurs and dioxygen action to electronically modify 2 by making it more electrophilic, (4) hydrosilylation being but one case of the reactivity of 2 with nucleophiles; the reaction with R″OH where R″ = H or alkyl is discussed. The effect of the electronic nature of the substituents on the rate of hydrosilylation was measured. Electron withdrawing substituents, R, on R3SiH accelerate the rate of addition to olefins, e.g. the rate of addition of (EtO)3SiH to olefins proceeds at a higher rate than the addition of Et3SiH to olefins. Electron donating groups, R′, on R′CH=CH2 greatly accelerate the rate of R3SiH to olefins, e.g. the Et3SiH addition occurs at a faster rate to Me3SiCH=CH2 than to Cl3SiCH=CH2. The relative rate of addition of (EtO)3SiH to a series of para-substituted styrenes was studied which confirmed the trend that higher rates of addition of R3SiH occurs to olefins, R′CH=CH2 with more electron donating substituents, R′. The origin of the cocatalytic effect of dioxygen in hydrosilylation was studied by generating Pt colloid under an atmosphere containing 16O2 and 18O2 and noting that the O-O bond is not broken and reformed under these conditions. It was demonstrated that the proposed intermediate 2 behaves as an electrophile by showing that Me3SiCH2CH=CH2 exchanges with Et3SiH in the presence of Pt to give trapped products based on the rearranged products Me3SiH and Et3SiCH2CH=CH2 in the presence of an electrophile (in this case Pt/Et3SiH). The reaction of water with R3SiH in the presence of a Pt catalyst in commercial silicone foams produces H2, and this reaction is described in the context of hydrosilylation where the water nucleophile replaces the olefin.
A Convenient Synthesis of Primary Amines by N-Alkylation of Cyclic Potassium Disilylamides
Hosomi, Akira,Kohra, Shinya,Tominaga, Yoshinori,Inaba, Masahiro,Sakurai, Hideki
, p. 2342 - 2345 (2007/10/02)
Potassium 2,6-disilapiperidide, readily prepared from 2,2,6,6-tetramethyl-2,6-disilapiperidine and potassium hydride, can be smoothly N-alkylated with alkyl halides to give the corresponding primary amines after acid hydrolysis.Keywords- potassium 2,6-disilapiperidide; potassium hydride; primary amine; N-alkylation; metal amide
Carbanion Rearrangements of ω-Phenyl-ω-(trimethylsilyl)alkyllithium Compounds: Intramolecular Reactions of Benzyltrimethylsilanes with a Carbon-Lithium Bond
Maercker, Adalbert,Stoetzel, Reinhard
, p. 1695 - 1706 (2007/10/02)
ω-Phenyl-ω-(trimethylsilyl)alkyllithium compounds show four out of five theoretically conceivable possibilities for intramolecular stabilization depending on the solvent and on the chain length n.While transmetalation of a methyl group at the silicon atom by a 1,(n+2) proton transfer is observed in any case, the intramolecular 1,n shift of the benzylic proton does only take place with n >/= 4.The main reaction, however for n = 3 and 4 only, is represented by the 1,n trimethylsilyl shift via a cyclic ate complex as an intermediate which partly splits off methyllithium yielding the corresponding silacycloalkane derivatives.In going from diethyl ether to THF as the solvent, the silyl shifts are more accelerated than the proton shifts.In no case, however, a Grovenstein-Zimmermann rearrangement involving phenyl migration took place.Degenerate silyl shifts starting from α-deuterated ω-(trimethylsilyl)alkyllithium compounds could not be detected either.Only by introduction of a second trimethylsilyl group into the 3 position a 1,3-(C -> C)-trimethylsilyl shift is initiated again.
CARBANIONEN-UMLAGERUNGEN DURCH INTRAMOLEKULARE 1,ω-PROTONVERSCHIEBUNG. II. ZUR REAKTIONSWEISE VON 3-, 4- UND 5-LITHIOALKYL-TRIMETHYLSILANEN
Maercker, Adalbert,Eckers, Mechthild,Passlack, Michael
, p. 193 - 205 (2007/10/02)
ω-Lithioalkyltrimethylsilanes, prepared from ω-bromoalkyltrimethylsilanes and lithium metal, are fairly stable in diethyl ether as solvent.Upon addition of tetrahydrofuran, however, rearrangements take place, the modes of which are strongly dependent on the number of methylene groups between the lithium and the silicon atoms.With 3-lithiopropyltrimethylsilane an intramolecular 1,5-proton shift with the formation of lithiomethyldimethylpropylsilane is observed.With 4-lithiobutyl-trimethylsilane on the other hand, ring closure to 1,1-dimethylsilacyclopentane takesplace, whereby methyllithium is formed by intramolecular nucleophilic attack on silicon. 5-Lithiopentyltrimethylsilane finally shows ring closure as well as 1,7-proton shift, the ratio depending on the polarity of the solvent.
