17067-65-1Relevant articles and documents
Hydrogen/Halogen Exchange of Phosphines for the Rapid Formation of Cyclopolyphosphines
Barrett, Adam N.,Woof, Callum R.,Goult, Christopher A.,Gasperini, Danila,Mahon, Mary F.,Webster, Ruth L.
, p. 16826 - 16833 (2021/11/04)
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.
Electronic effects and the stereochemistries in rearrangement-displacement reactions of triaryl(halomethyl)silanes with fluoride and with alkoxide ions
Allen, John M.,Aprahamian, Steve L.,Sans, Esther A.,Shechter, Harold
, p. 3561 - 3574 (2007/10/03)
Tetrabutylammonium fluoride (TBAF) reacts with (halomethyl)diphenyl(para-substituted-phenyl)silanes (13, X = Cl), 14 (X = Br), and 15 (X = I) in ether solvents to give fluorodiphenyl(parasubstituted-phenylmethyl)silanes (17a) and fluorophenyl(phenylmethyl)(para-substituted-phenyl)silanes (20a) by attack on silicon and migrations of the phenyl or the para-substituted-phenyl groups to C-1 with displacement of chloride ion. Sodium methoxide in dioxane effects rearrangement displacements of 14 (X = Br) to yield methoxydiphenyl(para-substituted-phenylmethyl)silanes (17b) and methoxyphenyl(phenylmethyl)(para-substituted-phenyl)silanes (20b). The migratory aptitudes of the varied phenyl groups in rearrangement-displacements of 13 with F- at 25°C are p-CF3-Ph, 2.72 > p-Cl-Ph, 1.67 > Ph, 1.00 > p-CH3-Ph, 0.91 > p-CH3O-Ph, 0.58 > p-(CH3)2N-Ph, 0.55. For reactions of 14 with sodium methoxide in dioxane, the migratory aptitudes at 23°C are p-CF3-Ph, 2.53 > p-Cl-Ph, 1.64 > Ph, 1.00 > p-CH3O-Ph, 0.84 > p-CH5-Ph, 0.79 > p-(CH3)2N-Ph, 0.68. The migratory aptitudes in the above rearrangement-displacements are increased by electron withdrawing substituents, and logarithms of the migratory aptitudes give satisfactory linear correlations with σ and/or σ-zero values of the phenyl substituents. Hammett correlations however of the migratory aptitudes from reactions of F- with 13 (X = Cl) at 0 and -20°C, 14 (X = Br) at 23, 0, and -20°C, and 15 (X = I) at 23°C are not linear. (+)-(Bromomethyl)methyl-1 naphthylphenylsilane (23, [α]D23 +8.29°, cyclohexane) reacts with CsF and with TBAF in THF to give benzylfluoromethyl-1-naphthylsilane (51, [α]D25 = 0.00°, cyclohexane) and fluoromethyl-(1 naphthylmethyl)phenylsilane (52, impure) in 10.4:1 ratio along with unchanged 23 ([α]D23 8.29°, cyclohexane). Sodium methoxide and (+)-23 in dioxane at 25°C and at 0°C yield (+)benzylmethoxymethyl-1-naphthylsilane (64) and (+)-methoxymethyl(1-naphthylmethyl)phenylsilane (65) in ～9:1 ratio. The conversions of (+)-23 to (+)-64 occur with 93% inversion about silicon. Reaction of (+)-23 with sodium methoxide at 25°C to give (+)-65 also occurs with inversion. Further, sodium ethoxide and sodium 2-propoxide react with (+)-23 at 20-25°C by rearrangement displacements on silicon with phenyl migrations to yield (+)-benzylethoxymethyl-1-naphthylsilane (69) and (+)-benzylmethyl-1-naphthyl-2-propoxysilane (70), respectively, each with 95% inversion about silicon. The mechanisms of rearrangement-displacements of 13-15 and (+)-23 by fluoride and by alkoxide ions are discussed.
Fungicidal 1,2,4-triazole derivatives
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, (2008/06/13)
Silicon-containing 1,2,4-triazoles having broad-spectrum fungicidal activity have been discovered.
DETERMINATION DE STRUCTURES AU MOYEN DE LA RMN DU 29Si: TRANSFERT SELECTIF DE POPULATION AVEC LES METHYLCHLORODISILYLMETHANES
Deleris, G.,Birot, M.,Dunogues, J.,Barbe, B.,Petraud, M.,Lefort, M.
, p. 1 - 8 (2007/10/02)
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.
N-ETHYLENEDIAMINES
Hu, Chunye,He, Ji-Gang,O'Brien, D. H.,Irgolic, K. J.
, p. 31 - 38 (2007/10/02)
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.
Rearrangement and Cleavage of silanes by Organolithium Reagents: Conversion of Phenols into Benzylic Alcohols
Eisch, John J.,Galle, James E.,Piotrowski, Andrzej,Tsai, Miin-Rong
, p. 5051 - 5056 (2007/10/02)
The feasibility of converting phenols into their corresponding benzylic alcohols by means of novel Wittig rearrangement has been investigated.The method consists of (a) treating the phenol with (chloromethyl)trimethylsilane and base to produce the aryl (trimethylsilyl)methyl ether, (b) using sec- or n-BuLi in THF transform this ether into the α-(trimethylsilyl)benzylic alcohol, and (c) removing the silyl group with alcoholic KOH to yield the benzylic alcohol.With phenols, such as phenol itself, 2-naphthol, and 9-phenanthrol, benzylic alcohols were obtained in 50-80percent yields.Ring substituents of a nitro or methoxy type tend to favor α elimination in step b, at the expense of the Wittig rearrangement.The competitive nature of these latter two processes was examined as a function of substituents on the aryloxy groups or on the silicon, as well as a function of the lithium reagent and solvent employed.The independent synthesis and the thermal study of (phenoxymethyl)lithium demonstrated that in THF it undergoes an α elimination almost to the complete exclusion of any Wittig rearrangement.The relative importance of these two processes is discussed in terms of the locoselectivity of lithiation and an electron-transfer view of the Wittig aryl ether rearrangement.
SILAETHENE II. DARSTELLUNG UND CHARAKTERISIERUNG VON 1,3-DISILACYCLOBUTANEN
Auner, N.,Grobe, J.
, p. 151 - 178 (2007/10/02)
1,3-Disilacyclobutanes of the types R1R2SiSiR1R2 are prepared (a) by ring synthesis from chloromethylchlorosilanes R1R2Si(CH2Cl)Cl, (b) by thermolysis of monosilacyclobutanes , and (c) by substitution of chlorine with alkyl groups in SiCl-containing 1,3-disilacyclobutanes, obtained by procedures (a) or (b).The compounds have been characterized by analytical and spectroscopic investigations.The synthetic methods are critically compared.
