- Hydrogen/Halogen Exchange of Phosphines for the Rapid Formation of Cyclopolyphosphines
-
The hydrogen/halogen exchange of phosphines has been exploited to establish a truly useable substrate scope and straightforward methodology for the formation of cyclopolyphosphines. Starting from a single dichlorophosphine, a sacrificial proton "donor phosphine"makes the rapid, mild synthesis of cyclopolyphosphines possible: reactions are complete within 10 min at room temperature. Novel (aryl)cyclopentaphosphines (ArP)5 have been formed in good conversion, with the crystal structures presented. The use of catalytic quantities of iron(III) acetylacetonate provides significant improvements in conversion in the context of diphosphine (Ar2P)2 and alkyl-substituted cyclotetra- or cyclopentaphosphine ((AlkylP)n, where n = 4 or 5) formation. Both iron-free and iron-mediated reactions show high levels of selectivity for one specific ring size. Finally, investigations into the reactivity of Fe(acac)3 suggest that the iron species is acting as a sink for the hydrochloric acid byproduct of the reaction.
- Barrett, Adam N.,Woof, Callum R.,Goult, Christopher A.,Gasperini, Danila,Mahon, Mary F.,Webster, Ruth L.
-
supporting information
p. 16826 - 16833
(2021/11/04)
-
- The β-silicon effect. 4: Substituent effects on the solvolysis of 1-alkyl-2-(aryldimethylsilyl)ethyl trifluoroacetates
-
Solvolysis rates of 2-(aryldimethylsilyl)-1-methylethyl and 2-(aryldimethylsilyl)-1-tert-butylethyl trifluoroacetates were determined conductimetrically in 60% (v/v) aqueous ethanol. The effects of aryl substituents at the silicon atom on the solvolysis rates at 50 °C were correlated with σmacr; parameters of r+ = 0.15 with the Yukawa-Tsuno equation, giving ρ values of-1.5 for both secondary α-Me and α-tert-Bu systems. The ρ values for those secondary systems are less negative than-1.75 for the 2-(aryldimethylsilyl)ethyl system that proceeds by the Eaborn (non-vertical) mechanism, while they are distinctly more negative than-0.99 for 2-(aryldimethylsilyl)-1-phenylethyl system that should proceed by the Lambert (vertical) mechanism. There was a fairly linear relationship between the reaction constants (ρ) for the β-silyl substituent effects and the solvolysis reactivities for a series of β-silyl substrates. The solvolyses of the α-Me and tert-Bu substrates proceed through the transition state (TS) with an appreciable degree of the β-silyl participation, close to the Eaborn (non-vertical) TS rather than to the Lambert (vertical) TS. Copyright
- Fujiyama, Ryoji,Alam, Md. Ashadul,Shiiyama, Aiko,Munechika, Toshihiro,Fujio, Mizue,Tsuno, Yuho
-
experimental part
p. 819 - 827
(2011/04/24)
-
- Zinc-catalyzed nucleophilic substitution reaction of chlorosilanes with organomagnesium reagents
-
Zinc-catalyzed nucleophilic substitution reactions of chlo-rosilanes with organomagnesium reagents afford various tetraorganosilanes under mild reaction conditions. The reactions can be performed on large scale and allow efficient preparation of functionalized tetraorganosilanes.
- Murakami, Kei,Yorimitsu, Hideki,Oshima, Koichiro
-
experimental part
p. 1415 - 1417
(2009/06/28)
-
- Silver-catalyzed transmetalation between chlorosilanes and aryl and alkenyl Grignard reagents for the synthesis of tetraorganosilanes
-
(Chemical Equation Presented) The silver savior: Nucleophilic substitution reactions of chlorosilanes with aryl Grignard reagents have been developed which take place under silver catalysis to afford tetraorganosilanes (see scheme). This transformation is likely to be promoted by diarylargentate reagents that are generated in situ.
- Murakami, Kei,Hirano, Koji,Yorimitsu, Hideki,Oshima, Koichiro
-
supporting information; experimental part
p. 5833 - 5835
(2009/03/11)
-
- 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
-
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
-
p. 741 - 750
(2007/10/03)
-
- Rearrangements of Organosilicon Compounds Using Organoaluminum Reagents. Conversion of Phenyl- and Alkenyl(chloromethyl)silanes to Benzyl- and Allylsilanes
-
Various (chloromethyl)silanes undergo Wagner-Meerwein-type rearrangements using a catalytic amount of EtAlCl2 in dichloromethane.The resulting chlorosilanes have been converted to alkyl(or aryl)silanes with RMgX and/or to fluorosilanes with NH4HF2.In this way phenyl-, alkenyl-, and allyl(chloromethyl)silanes were converted to benzyl-, allyl-, and homoallylsilanes, respectively.Attempted rearrangements of methyl-, alkynyl-, and furyl(chloromethyl)silanes under these conditions were not successful.
- Hudrlik, Paul F.,Abdallah, Yousef M.,Kulkarni, Ashok K.,Hudrlik, Anne M.
-
p. 6552 - 6556
(2007/10/02)
-
- Process for the preparation of lactic acid silyl esters
-
Novel lactic acid silyl esters of the formula STR1 in which R represents alkyl or aryl, are obtained by a new process which comprises reacting a lactic acid of the formula STR2 with a chloromethylsilane of the formula STR3 in which R has the meaning indicated above, in the presence of a tertiary amine and, if appropriate, in the presence of an additional diluent, at temperatures between 50° and 120° C.
- -
-
-
- DETERMINATION DE STRUCTURES AU MOYEN DE LA RMN DU 29Si: TRANSFERT SELECTIF DE POPULATION AVEC LES METHYLCHLORODISILYLMETHANES
-
The selective population transfer (SPT) technique has been applied to 29Si NMR of the complete series of methylchlorodisilylmethanes, several of which are new compounds.A great enhancement of the signals was observed and unambiguous assignments based on the determination of 2J(Si-H) coupling constants could be made.The first example of this type is presented.
- Deleris, G.,Birot, M.,Dunogues, J.,Barbe, B.,Petraud, M.,Lefort, M.
-
-
- N-ETHYLENEDIAMINES
-
A series of N-organosilylalkyl-substituted ethylenediamines, R3Si(CH2)nNHCH2CH2NH2 (R = CH3, C6H5 or 4-CH3C6H4; n = 1 or 3), were prepared by the reaction of haloalkylsilanes with ethylenediamine.The cleavage of a methyl group from silicon by concentrated sulfuric acid was used for the preparation of 1,3-bis-1,1,3,3-tetramethyldisiloxane.The proton and carbon-13 NMR spectra of these compounds are reported.
- Hu, Chunye,He, Ji-Gang,O'Brien, D. H.,Irgolic, K. J.
-
-
- 1H NMR Study of some Substituted Acyclic Silaethanes, 2-Silapropanes and 2-Methyl-2-Silapropanes and their Rotameric Populations around the Si-C Bond
-
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).
- Carleer, Robert,Anteunis, Marc J. O.
-
p. 253 - 258
(2007/10/02)
-