61484-68-2Relevant academic research and scientific papers
NMR spectra of phenoxysilanes with various silyl groups
Hudrlik, Paul F.,Minus, Donald K.
, p. 157 - 162 (2007/10/03)
Ten phenoxysilanes with various organic groups on the silicon were prepared and their 1H and 13C NMR spectra recorded. The groups on the silicon had only a small effect on the proton and carbon chemical shifts.
N-(DIMETHYLALKOXYSILYLMETHYL)- AND N-(DIMETHYLARYLOXYSILYLMETHYL)LACTAMS
Artamkina, O. B.,Kramarova, E. P.,Shipov, A. G.,Baukov, Yu. I.,Macharashvili, A. A.,et al.
, p. 1590 - 1597 (2007/10/02)
A comparison is made of conditions and preparative possibilities of synthesizing Si-substituted N-(dimethylsilylmethyl)lactams with oxygen-containing substituents (alkoxides, aryloxides, benzoates, and triflates) by several methods: by reactions of N-(dimethylchlorosilylmethyl)lactams with sodium alkoxides and with alcohols in the presence of triethylamine, by exchange reactions with trimethylsilyl derivatives of alcohols, phenols, benzoic and trifluoromethylsulfonic acids, and also by a one-pot technique using lactam, dimethylchloromethylchlorosilane, and triethylamine with subsequent addition to the reaction mixture of the alcohol and triethylamine. In the reaction of N-(dimethylchlorosilylmethyl)lactams with sodium alkoxides, concurrently with the replacement of halogen by an alkoxy group the Si-C bond is split to form N-methyllactams, which can also be prepared by the reaction of the initial chlorides with potassium hydroxide. According to IR spectroscopy, intramolecular O->Si coordination is observed in aryloxy-, benzoyloxy-, and trifluoromethylsulfonyloxy derivatives of N-(dimethylsilylmethyl)lactams, whereas the corresponding alkoxy derivatives lack this interaction. The structure of 1-(dimethylsilylmethyl)-2-pyrrolidone phenoxide and benzoate, 1-(dimethylpentafluorophenoxysilylmethyl)perhydro-2-azepinone, and 1-(dimethyltrifluoromethylsulfonyloxymethyl)-2-piperidone was studied by x-ray structural analysis. The lengths of the axial (C=)O->Si and Si-O bonds are, respectively, 2.367 and 1.711(2) Angstroem for the first, 2.228 and 1.711(2) Angstroem for the second, 2.078 and 1.787(2) Angstroem for the third, and 1.753 and 2.785(2) Angstroem for the fourth compound. Variations in the bond lengths are due to the properties of the Si-substituent and to the size of the lactam rings. The ease of formation of the Si-substituted N-(dimethylsilylmethyl)lactams with oxygen-containing substituents via the exchange reaction of N-(dimethylchloromethyl)lactams with the corresponding trimethylsiloxy derivatives correlates with the strength of the silicon-oxygen coordination in the reaction products.
Pentacoordinate silicon intermediates in relay substitution reactions of organosilanes: successive nucleophilic attack at silicon and its adjacent carbon
Eisch, John J.,Chiu, Chingchen S.
, p. C1 - C5 (2007/10/02)
Chloromethylsilyl chlorides of the type, ClCH2R2SiCl, have been shown to undergo kinetically controlled nucleophilic attack at silicon, with either phenols or amines (PhEH, with E=O or NMe), to yield products of the type, PhESiR2CH2Cl.Subsequent treatment of the latter products with KF in acetonitrile causes the nucleophile to be shifted from silicon to carbon with the formation of FSiR2CH2EPh.Alternatively, treatment of ClCH2R2SiCl simultaneously with PhEH and KF yields the same thermodynamically controlled product directly, FSiR2CH2EPh.This possibility of directing nucleophilic attack toward silicon or its adjacent carbon has great importance in the synthesis of substituted organosilanes.The mechanism of these so-called relay nucleophilic substitutions is proposed as involving pentacoordinate silicon intermediates.The concept of initial nucleophilic attack at silicon and the subsequent relaying of the nucleophile from the pentacoordinate silicon to the adjacent carbon is also shown to be applicable to the unusual reactions of α,β-epoxyalkylsilanes.
1H NMR Study of some Substituted Acyclic Silaethanes, 2-Silapropanes and 2-Methyl-2-Silapropanes and their Rotameric Populations around the Si-C Bond
Carleer, Robert,Anteunis, Marc J. O.
, p. 253 - 258 (2007/10/02)
Three series of substituted silaalkanes, (i) SiH3CH2X, (ii) MeSiH2CH2X and (iii) Me2SiHCH2X, have been prepared (X=Cl, Br, I, NMe2, OMe, SMe), and the shifts and coupling constants extracted from their 1H NMR spectra.Coefficients averaged over three rotameric states can be obtained from the first series which are used for the correction of coupling constants resulting from the presence of the electronegative substituents X.With the aid of the Karplus-Conroy angular dependence of the interproton coupling constants in silaethane fragments, corrected for electronegative substitution, approximate rotameric population in series ii and iii were obtained.Except for X=NMe2, there is always a preference for a synclinal X/CH3 relationship, even for sandwiched situation (series iii).
