Norbert Duffaut

Silylation d'hydrocarbures mono-aromatiques mono- ou disubstitues

Abstract In the presence of lithium and in tetrahydrofuran as solvent, trimethylchlorosilane reacts at 0–10°C, in an inert atmosphere, with monoaromatic mono- or disubstituted hydrocarbons, to give the corresponding 1,4-disilyl derivatives. In the case of ortho -xylene and cumene, disilylation is accompanied by tetrasilylation, whereas phenyltrimethylsilane can lead to the tetrasilylated derivative in quantitative yields. 1,3-Dichlorotetramethyldisiloxane reacts with benzene to give: Most of the products described are new compounds.

Application du systeme Me3SiClLiTHF a la synthese d'acylsilanes, d'alcools, d'aldehydes, d'esters et de nitriles C-silicies

Abstract Synthesis of C -silylated products by silylation of various functional saturated derivatives (aldehydes, nitriles, acid anhydrides and esters), by mens of the Me 3 SiClue5f8Liue5f8THF system used at 0–10°C, is described. Most of the products obtained are new. A mechanism explaining the formation of these derivatives is proposed.

Nouvelle méthode de création de la liaison silicium-carbone à partir de chlorosilanes VII. C-silylation d'esters

Abstract The trimethylchlorosilane/magnesium/hexamethylphosphoric triamide system reacts with methyl benzoate to lead to an O - and C -silylated mixed ketal, which under hydrolysis easily gives benzoyltrimethylsilane (new preparative method of this compound), but which in basic media is converted to an unexpected siloxanic isomer. Under the same conditions trimethylsilyl benzoate gives, after hydrolysis, an α- C -disilylated alcohol.

C-silylation et duplication réductrice observées lors de l'action de Me3SiClMgHMPT sur des composés carbonylés α-éthyléniques. : Application à la préparation d'εdicétones à partir de cétones α-éthyléniques

Abstract Two reactions, the 1,4-disilylation and the reductive duplication accompanied by O -silylation, can chiefly occur by action of the Me 3 SiClue5f8Mgue5f8HMPT system on various α-ethylenic carbonylated compounds. When the sequence of such derivatives is conjugated with another group , the 1,4-disilylation is the main reaction and affords upon hydrolysis the corresponding derivative β-silylated with respect to the carbonyl group (new illustrative example: the pseudo-ionone). In contrast to this, when the sequence is not conjugated with another group, the reductive duplication accompanied by O -silylation occurs and leads, after hydrolysis, to the corresponding e-diketone (examples: methylbutenone, 2-cyclohexenone and isophorone). Such a reaction can be used in organic synthesis to prepare e-diketones from α-ethylenic ketones. A mechanism permitting homogeneous interpretation of all our results in this domain is proposed.

Some practical uses of the disilane residue from the direct synthesis of methylchlorosilanes

Abstract Some practical uses for the disilane residue from the direct synthesis of methylchlorosilanes have been proposed. This residue can be converted into organochloro-(Me 2 SiCl 2 , MeSiCl 3 , Me 3 SiCl) or organohydrochloro-monosilanes (HMeSiCl 2 , HMe 2 SiCl). These disilanes can also be used for the synthesis of alkyl (haloalkyl, alkenyl, aryl, etc.) methyldichlorosilanes or alkyl (haloalkyl, alkenyl, aryl, etc.) trichlorosilanes. The reductive properties of the Si-Si bond of these species have been utilized (e.g. in the reduction of phosphine oxides into the corresponding phosphines). Polysilanes resulting from the disproportionation of this residue are precursors of polycarbosilanes.

Sulfonation comparee de groupes divers lies au silicium. Application a la synthese d'acides sulfoniques nouveaux

Abstract Sulphonation by trimethylsilyl chlorosulphonate of various substituted silicon compounds is regiospecific or highly regioselective at the silicon atom, the reaction order is found to be: allyl > α-naphthyl > phenyl > vinyl. Sulphonation of various mono- and di-silylated derivatives leads to trimethylsilylmono- and in some cases to trimethylsilyldisulphonates which by hydrolysis form new sulphonic acids. The orientation of the sulphonation is determined by the position of the silicon atom. The nature of cyclohexyl hinders sulphonation (cyclo-C 6 H 11 Si is much less reactive than MeSi), while cyclopropanyl, due to its π-character, is much more reactive.

Nouvelle methode de C-silylation directe de cetones saturees ou α-ethyleniques

Abstract A new method to effect the direct C -silylation of ketones is proposed by reaction with the Me 3 SiCl/Li/THF system. With saturated ketones or with α-ethylenic ketones in which the sequence is not conjugated with another group, direct C -silylation has been carried out for the first time. Under mild conditions (0–10°C), the reaction occurs with good yields. Various new compounds have been synthetized; ketones β-silylated with respect to tile carbonyl group, α-silylated allylic or saturated alcohols and silylated conjugated hydrocarbons. A mechanism for the formation of these derivatives is proposed. This work constitutes an important extension of direct C -silylation reactions of functional compounds by means of chlorosilanes.

Creation de la liaison silicium-carbone par silylation reductrice de composes fonctionnels allyliques et benzyliques; influence des groupes SiMe3 sur la stabilisation des anions

Abstract The Me3SiCl/Mg/HMPT system reacts with several functional substituted benzylic or allylic compounds (alkoxysilanes, ethers, amines etc.) and leads to a reduction of the function with C-silylation. These reactions generally need catalysts (transition metal complexes), except with α-silylated or with trityl compounds, when stabilization of the intermediate carbanions, especially by the trimethylsilyl group, takes place.

C-silylation de cétones a partir de chlorotrialkylsilanes et de magnésium

Abstract The trimethylchlorosilane/magnesium/hexamethylphosphorictriamidesystem reacts with arylaliphatic ketones suffering steric hindrance to yield the corresponding C -substituted silicon alcoxysilanes, which after hydrolysis, lead to C -substituted silicon homologs of tertiary alcohols. Furthermore, under certain conditions phenyl-tert-butylketone can give para -substituted alcoxysilane which upon hydrolysis yields the para -silyl-substituted secondary alcohol.

Sulfonation de dérivés siliciés acétyléniques et alléniques fonctionnels

Abstract Sulfonating agents such as trimethylsilyl chlorosulfonate and “dioxane, SO 3 ”, react with silylalkynes (ΣCH 2 Cue5fcCSiMe 3 ) in which Σ is a functional group, to yield silylacetylene sulfonates (Σ = OMe, Cl), acetylenic sulfates (Σ = OH, OSiMe 3 ) or SO 3 nitrogen adduct (Σ = NR 2 ). Allenoxysilanes Me 3 Si(Σ 1 )Cue5fbCue5fbC(Σ 2 )OSiMe 3 yield either allenic sulfate (Σ 1 = Me 3 Si, Σ 2 = t-Bu) or silyl ketonic sulfonate (Σ 1 = n-Bu, Σ 2 = t-Bu). A mechanism is proposed for these reactions.