17898-21-4Relevant academic research and scientific papers
On the mechanism of metal colloid catalyzed hydrosilylation: Proposed explanations for electronic effects and oxygen cocatalysis
Lewis, Larry N.
, p. 5998 - 6004 (1990)
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.
Synthesis and reactions of donor cyclopropanes: efficient routes to cis- and trans-tetrahydrofurans
Dunn, Jonathan,Dobbs, Adrian P.
supporting information, p. 7386 - 7414 (2015/08/24)
Abstract A detailed study on the synthesis and reactions of silylmethylcyclopropanes is reported. In their simplest form, these donor-only cyclopropanes undergo Lewis acid promoted reaction to give either cis- or trans-tetrahydrofurans, with the selectivity being reaction condition-dependant. The adducts themselves are demonstrated to be an important scaffold for structural diversification. The combination of a silyl-donor group in a donor-acceptor cyclopropane with novel acceptor groups is also discussed.
Donor cyclopropanes in synthesis: Utilising silylmethylcyclopropanes to prepare 2,5-disubstituted tetrahydrofurans
Dunn, Jonathan,Motevalli, Majid,Dobbs, Adrian P.
scheme or table, p. 6974 - 6977 (2012/02/13)
The use of donor-only silylmethylcyclopropanes in the Lewis acid promoted reaction with aldehydes to generate 2,5-disubstituted tetrahydrofurans is described. The diastereoselectivity obtained in the product is very much dependent upon the temperature of
Mesoporous aluminosilicate-catalyzed allylation of carbonyl compounds and acetals
Ito, Suguru,Hayashi, Akira,Komai, Hirotomo,Yamaguchi, Hitoshi,Kubota, Yoshihiro,Asami, Masatoshi
supporting information; body text, p. 2081 - 2089 (2011/04/19)
A mesoporous aluminosilicate (Al-MCM-41) was found to be an effective heterogeneous catalyst for the reaction of both carbonyl compounds and acetals with allylsilanes to afford the corresponding homoallyl silyl ethers and homoallyl alkyl ethers, respectively. Both the mesoporous structure and the presence of aluminum moiety were indispensable for the high catalytic activity of Al-MCM-41. Moreover, Al-MCM-41 could catalyze the reaction of acetals chemoselectively in the presence of the corresponding carbonyl compounds. The solid acid catalyst Al-MCM-41 could be recovered easily by filtration and could be reused three times without a significant loss of catalytic activity.
Process for the preparation of vinyl- or allyl-containing compounds
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Page/Page column 6, (2008/06/13)
A vinyl- or allyl-containing compound represented by following Formula (3): wherein R2, R3, R4, R5, and R6 each represent hydrogen atom or a nonmetallic atom-containing group; R7 represents a nonmetallic atom-containing group; Y represents a group selected from the group consisting of —Si(R8) (R9) —, —Si(R10) (R11)—O—, the left hand of which is combined with R7, and —NR12—, wherein R8, R9, R10, R11, and R12 each represent hydrogen atom or a nonmetallic atom-containing group; and “n” represents 0 or 1, is prepared by reacting a vinyl or allyl ester compound represented by following Formula (1): wherein R1 represents hydrogen atom or a nonmetallic atom-containing group; R2, R3, R4, R5, R6, and “n” are as defined above, with a compound represented by following Formula (2): [in-line-formulae]R7—Y—H ??(2)[/in-line-formulae] wherein R7 and Y are as defined above, in the presence of a transition element compound.
Pd-catalyzed coupling reaction of allyl and propargyl ethers with chlorosilanes
Naitoh, Yoshitaka,Bando, Fumiaki,Terao, Jun,Otsuki, Kazutaka,Kuniyasu, Hitoshi,Kambe, Nobuaki
, p. 236 - 237 (2008/02/04)
Pd-catalyzed synthesis of allylsilanes from chlorosilanes and allyl ethers is described. The reaction proceeds efficiently at room temperature by the use of phenyl or vinyl Grignard reagent in the presence of palladium catalysts. The present method can also be applied to synthesis of propargylsilanes by the use of propargyl ethers. Copyright
Novel nickel-catalyzed coupling reaction of allyl ethers with chlorosilanes, alkyl tosylates, or alkyl halides promoted by vinyl-Grignard reagent leading to allylsilanes or alkenes
Terao, Jun,Watabe, Hiroyasu,Watanabe, Hiroyuki,Kambe, Nobuaki
, p. 1674 - 1678 (2007/10/03)
A new method for a carbon-silicon or carbon-carbon bond forming reaction between allyl ethers and chlorosilanes, alkyl tosylates, or alkyl halides giving rise to allylsilanes or alkenes has been developed. This reaction proceeds efficiently at ambient temperature by the combined use of nickel catalysts and a vinyl-Grignard reagent. A possible reaction pathway involving the formation of allyl-Grignard reagents via transmetallation of π-allylnickel complexes with the vinyl-Grignard reagent and subsequent trapping of the thus formed allyl-Grignard reagents with electrophiles is proposed.
Titanocene-catalyzed carbosilylation of alkenes and dienes using alkyl halides and chlorosilanes
Nii, Shinsuke,Terao, Jun,Kambe, Nobuaki
, p. 5291 - 5297 (2007/10/03)
A new method for regioselective carbosilylation of alkenes and dienes has been developed by the use of a titanocene catalyst. This reaction proceeds efficiently at 0 °C in THF in the presence of Grignard reagents by the combined use of alkyl halides (R'-X, X = Br or Cl) and chlorotrialkylsilanes (R3'Si-Cl) as the alkylating and silylating reagents, respectively. Terminal alkenes having aryl or silyl substituents (YRC=CH2, Y = Ar or Me3Si, R = H or Me) afford addition products YRC- (SiR(3))-CH2R' in good yields, whereas 1-octene and internal alkenes were sluggish. When 2,3-disubstituted 1,3-butadienes were used instead of alkenes, alkyl and silyl units are introduced at the 1- and 4-positions giving rise to allylsilanes in high yields under similar conditions. The present reaction involves (i) addition of alkyl radicals toward alkenes or dienes, and (ii) electrophilic trapping of benzyl- or allylmagnesium halides with chlorosilanes. The titanocene catalyst plays important roles in generation of these actiye species, i.e., alkyl radicals and benzyl- or allylmagnesium halides.
A one-pot preparation of allylsilanes and (Z)-alk-2-enylsilanes
Desponds, Olivier,Franzini, Livia,Schlosser, Manfred
, p. 150 - 152 (2007/10/03)
Metalation of alk-1-enes, using the mixture of butyllithium and potassium tert-butoxide in tetrahydropyran, followed by stereohomogenization and ultimate treatment with chlorotrimethylsilane afforded a series of alk-2-enyltrimethylsilanes in good yield and with (Z/E) ratios ranging from 95:5 to 98:2. The deprotonation of propene can be rapidly and readily accomplished with a stoichiometric amount of the superbase suspended in pentane on a 1 mol scale.
New hexacoordinate silicon complexes, the process for their preparation and their application
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, (2008/06/13)
The present invention relates to new hexacoordinate silicon complexes, the process for their preparation and their application. These new complexes correspond to the general formula I: STR1 in which: A represents an alkali metal or alkaline earth metal except for magnesium, and n=0 or 1.
