18415-23-1Relevant articles and documents
The synthesis of stable intramolecularly dialkylamino-coordinated silenes and their methyl iodide induced isomerization into cyclic aminosilanes
Mickoleit, Martin,Schmohl, Kathleen,Michalik, Manfred,Oehme, Hartmut
, p. 1538 - 1544 (2004)
The reaction of the (dichloromethyl)oligosilanes R(Me3Si) 2-SiCHCl2 4a-d (4a: R = Me; 4b: R = tBu; 4c: R = Ph-, 4d: R = SiMe3) with 8-(dimethylamino)-1-naphthyllithium leads to the intramolecularly donor-stabilized silenes 1a-d. Whereas 1a.b, and d were isolated as thermally stable yellow crystalline compounds, 1c could not be separated in a pure form but was characterized by NMR spectroscopy and mass spectroscopy as well as by its chemical reactivity with a variety of substrates. Dynamic 1H NMR spectroscopic studies of 1a and 1d revealed coalescence of the signals of the two CSiMe3 groups. In agreement with theoretical calculations, this effect was interpreted as the result of internal rotations about the silene double bond. These findings and the known relatively long Si=C distances for 1d, 2 and 3 help establish the ylide-like nature of the silenes prepared. Treatment of 1a-d with water produced the silanols 9a-d. Treatment of 1a,b, and d with methyl iodide caused a rearrangement of the silenes, one methyl substituent formally migrating from the coordinated dimethylamino group to the silene carbon atom producing the respective cyclic aminosilanes 11a,b, and d. As the outcome of the reaction of 1d with benzaldehyde, 2,2-bis(tri-methylsilyl)vinylbenzene (14) and a mixture of the two isomers of the cyclodisiloxane 13 were obtained. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
PHOTOLYSIS AND PYROLYSIS OF POLYSILYLATED DIAZOMETHANES. EFFECTIVE MIGRATING TENDENCY OF TRIMETHYLSILYL GROUP TO A CARBENE CENTER
Sekiguchi, Akira,Ando, Wataru
, p. 871 - 874 (1983)
Photolysis and pyrolysis of polysilylated diazomethanes were investigated, and a selective migration of trimethylsilyl group to a carbene center was observed.
Comparison of tris(dimethylphenylsilyl)methyllithium and tris(trimethylsilyl)methyllithium reactions with carbon disulfide: A new route for the synthesis of some 1,1-bis(benzylthio) and bis(allylthio)-2,2- bis(dimethylphenylsilyl)ethenes
Safa, Kazem D.,Ghorbanpour, Khatereh
, p. 304 - 311 (2014/04/03)
A series of bis(benzylthio) and bis(allylthio)-2,2-bis(dimethylphenylsilyl) ethenes has been obtained by the reaction of (PhMe2Si) 3CLi and CS2 with benzyl and allyl bromides. A plausible mechanism for the formation of these compounds has been proposed. The reactivity of (PhMe2Si)3CLi toward CS2 has been compared with that of (Me3Si)3CLi. The reaction of (PhMe 2Si)3CLi with CS2 and 2-methyloxirane gave a cyclic thiocarbonate(equation presented). 2014
Reactivity of the triple ion and separated ion pair of tris(trimethylsilyl) methyllithium with aldehydes: A RINMR study
Jones, Amanda C.,Sanders, Aaron W.,Sikorski, William H.,Jansen, Kristin L.,Reich, Hans J.
, p. 6060 - 6061 (2008/12/20)
Low-temperature rapid-injection NMR (RINMR) experiments were performed on tris(trimethylsilyl)methyllithium. In THF/Me2O solutions, the separated ion (1S) reacted faster than can be measured at -130 °C with MeI and substituted benzaldehydes (k ≥ 2 s-1), whereas the contact ion (1C) dissociated to 1S before reacting. Unexpectedly, the triple ion reacted faster with electron-rich benzaldehydes relative to electron-deficient ones. The addition of HMPA had no effect on the rate of reaction of the triple ion with p-diethylaminobenzaldehyde, and the immediate product of the reaction was the HMPA-solvated separated ion 1S, with the Peterson product forming only slowly. Thus, the aldehyde is catalyzing the dissociation of the triple ion. HMPA greatly decelerated the reaction of 1S (-10), providing an estimate of the Lewis acid activating effect of a THF-solvated lithium cation in an organolithium addition to an aldehyde. Copyright
Intramolecularly donor-stabilized silenes: Part 6. the synthesis of 1-[2,6-bis(dimethylaminomethyl)phenyl]silenes and their reaction with aromatic aldehydes
B?umer, Ute,Reinke, Helmut,Oehme, Hartmut
, p. 229 - 239 (2007/10/03)
The intramolecularly donor-stabilized silenes ArR1SiC(SiMe 3)2 (3a-d) (3a: R1 = Me; 3b: R1 = t-Bu; 3c: R1 = Ph; 3d: R1 = SiMe3; Ar = 2,6-(Me2NCH2
A new selective approach to 1,1-bis(silyl)-2-arylethenes and 1,1-bis(silyl)-1,3-butadienes via sequential silylative coupling-heck coupling reactions
Pawluc, Piotr,Hreczycho, Grzegorz,Marciniec, Bogdan
, p. 8676 - 8679 (2007/10/03)
A novel selective route to 1,1-bis(silyl)-1-alkenes has been developed. Sequential one-pot silylative coupling exo-cyclization of 1,2- bis(dimethylvinylsiloxy)ethane followed by the reaction with Grignard reagents leads to the desired 1,1-bis(silyl)ethene
The reaction of substituted vinylsilanes with lithium metal
Maercker, Adalbert,Reider, Kerstin,Girreser, Ulrich
, p. 1455 - 1465 (2007/10/03)
Vinylsilanes are known to react with lithium metal to form either 1,2-dilithioethanes by reduction or 1,4-dilithiobutanes by reductive dimerization. The reaction of the substituted vinylsilanes 3, (Z)-13b, 17b, c, 42b, c, 44, and 51 with lithium has been investigated. Depending on the substituents on the vinylsilane and the solvent employed, several new reaction pathways are observed, which have been proved by independent syntheses of the reactive intermediates (E)-14b, 18d, and 25-27. Thus, besides the known elimination of lithium hydride, either a 1,4-proton shift of 25 to 26 or a Grovenstein-Zimmerman rearrangement of 45 to 47 can occur as follow-up reactions. Furthermore, two different types of dimerization of the silyl-substituted vinyllithium compounds have been identified. Either the vinyllithium compound 18d adds to the starting vinylsilane leading to the monolithiumorganic species 41, or lithium metal catalyzed dimerization to the 1,4-dilithio-2-butene derivative 49 takes place, which is without precedence.
Chromium(II)-mediated synthesis of vinylbis(silanes) from aldehydes and a study of acid- and base-induced reactions of the derived epoxybis(silanes): A synthesis of acylsilanes
Hodgson, David M.,Comina, Paul J.,Drew, Michael G. B.
, p. 2279 - 2289 (2007/10/03)
The synthesis of vinylbis(silanes) 1 from aldehydes and dibromomethylenebis(trimethylsilane) using chromium(II) chloride in DMF is described. Epoxidation of vinylbis(silanes) 1 and treatment of the resulting epoxybis(silanes) 2 with sulfuric acid in metha
On the silaethene tBu2Si=C(SiMe3)2, and the structure and reactivity of its [4 + 2] cycloadduct with Ph2C=O
Wiberg, Nils,Hwang-Park, Hae-Sook,Lerner, Hans-Wolfram,Dick, Stefan
, p. 471 - 478 (2007/10/03)
From tBu2SiF-CLi(SiMe3)2 by LiF elimination only Me2Si=C(SiMe3)(SiMetBu2) (1b) instead of tBu2Si=C(SiMe3)2 (1a) is isolated. With benzophenone, silaethene 1b (from its THF adduct 1b · THF) forms at -78°C a yellow [4 + 2] cycloadduct (5) and a colorless [2 + 2] cycloadduct (6). With increasing temperature 5 transforms into 6, and 6 transforms - more slowly - into the yellow [4 + 2] cycloadduct (7) of 1a and Ph2CO. It follows from this that the migration equilibrium 1a ? 1b really exists. The structure of 7 shows a planar -O-CPh=C6H5 - framework with the cycloadded atoms Si and C from -tBu2Si-C(SiMe3)2- located above the plane. The =C6H5-C bond (1.62 A) is exceptionally long. 7 is a source for la which is trapped by acetone (formation of an ene product) and by benzaldehyde [formation of a [2 + 2] cycloadduct, unstable against cydoreversion into PhHC=C(SiMe3)2 and tBu2SiO-containing substances]. Reaction of 7 with trimethylsilyl azide, less reactive than acetone or benzaldehyde, leads - by way of la which transforms into 1b - to a trapping product of 1b (formation of a [3 + 2] cycloadduct, unstable against transformation into (RMe2Si)(Me3Si)CN2 with R = (Me3Si)2N, or cydoreversion into (tBu2MeSi)(Me3Si)CN2 and Me2SiNSiMe3-containing substances). Reaction of 1b or 1b · THF with acetone leads only to an ene reaction product of 1b. This means, that only undetectable amounts of 1a or 1a · THF are in equilibrium with 1b or 1b · THF. A minor substance which is shown by NMR at low temperatures besides 1b or 1b · THF is interpreted as a retamer of 1b or 1b · THF. VCH Verlagsgsellschaft mbH, 1996.
Reactivity of the Silaethene Ph2Si=C(SiMe3)2
Wilberg, Nils,Link, Matthias
, p. 1231 - 1240 (2007/10/03)
Silaethene Ph2Si=C(SiMe3)2 (3), generated as a reaction intermediate by the thermal elimination of LiX from Ph2SiX-CLi(SiMe3)2 (X = Br, F) or by the thermal cycloreversion of the cycloadduct of 3 and Ph2C=NSiMe3, forms adducts 3*donor, the stability of which increases in the order of donor = Et2O according to an ene reaction, with a=b (e.g.CH2=CHOMe; Ph2C=NSiMe3) or a=b=c (e.g. (t-Bu)2RSiN3, R = Me, t-Bu) or a=b-c=d with or or cycloaddition.The following order of relative reactivity of trapping reagents for Ph2Si=C(SiMe3)2 was found: Ph2CO > (t-Bu)2MeSiN3 > butadiene > 2,3-dimethylbutadiene > Ph2CNSiMe3 > (t-Bu)3SiN3 > anthracene.Summing up, it may be said that going from Me2Si=C(SiMe3)2 to Ph2Si=C(SiMe3)2 there is only a gradual but not principal change of silaethene reactivity.This change is due to increasing polarity and overcrowding of the double bond, that is increasing Lewis acidity and steric hindrance of the unsaturated silicon atom.Certainly, the former silaethene stabilizes thermally by dimerization, the latter by isomerization. - Keywords: Adduct formations, insertions, ene reactions, -, -, -cycloadditions of Ph2Si=C(SiMe3)2 ; Reactivity order of traps ; Reactivity of Me2Si=C(SiMe3)2 and Ph2Si=C(SiMe3)2
