M. Lesbre

Sultones organométalliques : IV. Réactions de sulfonation en série silacyclobutanique

Abstract The behaviour of some substituted silacyclobutanes with respect to sulfur trioxide and other sulfonating agents (SO 3 /dioxane, trimethylsilyl chlorosulfonate) is studied. The 1,1-dialkylated derivatives of silacyclobutane, 2-methylsilacyclobutane and 3-methylsilacyclobutane as well as the spiranes of the type (CH 2 ) n Si(CH 2 ) 3 ( n = 4 or 5) react with sulfur trioxide to give 4-sila-1,4-butanesultones. On the other hand, the alkoxylated or dialkylaminated derivatives fix SO 3 via the functional group, thus giving silacyclobutanyl sulfates or amidosulfates of the type XSO 2 O(R)Si(CH 2 ) 3 (X = OR′, NR′ 2 ). The sulfonation of 1-methyl-1-phenylsilacyclobutane leads mainly to 1-methyl-1-silacyclobutylbenzenesulfonate, besides the expected sultone. The structure of the insertion products of SO 3 in the SiC, SiN, SiO and SiCl bonds is deduced from their infrared and protonic resonance spectra. Reaction mechanisms, permitting to ascertain the role of the substituents on the mode of insertion of sulfur trioxide and the reactivity of the cyclobutane SiC bond, are considered.

Ene-reactions en series organosiliciee et germaniee

Abstract Ene reactions involving enes and enophiles of silicon and germanium have been investigated. Organometallic δ-ethylenic compounds were synthesized and an allylic group converted into a vinylic one , to obtain 1-sila- or 1-germacyclopent-2-enes.

Germacycloalcanes à quatre et cinq chaînons

Resume Une nouvelle synthese du germacyclopentane, et de ses derives substitues, a partir du diphenyldibromogermane est decrite. Les germacyclobutanes sont prepares par la methode de cyclisation monomoleculaire par le sodium des derives 1,4-dihalogenes du type R 2 Ge(X)-(CH 2 ) 3 X. La structure de ces nouveaux composes est demontree par une etude physique, et par leur grande reactivite chimique comparee a celle des germacycloalcanes a cinq et six chainons.

Réactions d'expansion du cycle germacyclobutanique par le soufre et le sélénium moléculaires

Abstract Sulphur and selenium enter into the cycle of germacyclobutane between germanium and carbon, which leads to the formation of germatetrahydrothiophenes and germatetrahydroselenophenes. The structure of these new cyclic compounds was determined by mass and NMR spectrometry. Cyclisation of 1,4-dihalogenated derivatives by sodium sulphide resulted in the formation of the same heterocycles.

Mécanisme et stéréochimie des réaction d'addition des alcoyl- et alcoylhalogénogermanes sur le chlorure de propargyle

Abstract The organogermanium hydrides and halohydrides R 3 GeH, R 2 (Cl)GeH, R(Cl) 2 GeH and Cl 3 GeH react with propargyl chloride according to three competitive reactions of the GeH bond: addition on the triple bond giving several ethylenic isomers of the gemanium group; reduction of propargyl chloride to propyne and condensation/elimination with formation of a β-acetylenic organogermanium compound and release of HCl. The corresponding percentages of the different reactions are highly variable depending on the hydrides and the experimental conditions. They allow to study the mechanism and the stereochemistry of the addition, and to follow the variation of the polarity of the GeH bond as a function of the electronic effects of the substituents bonded to germanium.

Halomethylmetal compounds : XLIX. The insertion of phenyl(bromodichloromethyl)mercury-derived dichlrocarbene into carbonhydrogen bonds: tetraalkylgermanes. Thermolysis of 3-dichloromethyl-1-metallacycloalkanes

Phenyl(bromodichloromethyl)mercury-derived dichlorocarbene was found to insert into βCH bonds of a number of tetraalkylgermanes: into the n-propyl group of Et3GeCH2CH2CH3, the isobutyl group of Et3GeCH2CHMe2, the trimethylene bridges of Et3Ge(CH2)3GeEt3 and 1,1,2,2-tetraethyl-1,2-digermacyclopentane, the tetramethylene bridge of 1,1,2,2-tetraethyl-1,2-digermacyclohexane and the pentamethylene bridge of 1,1-diethyl-1-germacyclohexane. Pyrolysis of these insertion products resulted in γ-elimanation of GeCl to give germyl-substituted chlorocyclopropanes, reactions which served well in confirming the structures of the insertion products. For instance, thermolysis of 1,1-diethyl-3-dichloromethyl-1-germacyclohexane gave 1-chloro-2-(γ-diethylchlorogermylpropyl)cyclopropane. The various insertion products were reduced to the chlorine-free methyl derivatives, e.g., Et3GeCH2C(CCl2H)Me2 to Et3GeCH2CMe3. A competition between Et3GeCH2CHMe2 and Et3SiCH2SiCH2CHMe2 for a deficiency of PhHgCCl2Br showed the germane to be 1.35 times more reactive toward this CCl2 source than the silane. The pyrolysis of 1,1-dimethyl-3-dichloromethyl-1-silacyclopentane and -cyclohexane, as well as of 1,1-dimethyl-3-dichloromethyl-1-stannacyclohexane was also studied.

Sila-3 et germa-3 bicyclo[3.1.0] hexanes

Abstract The 3-sila- and 3-germabicyclo[3.1.0] hexanes, with various substituents at the heteroatom, are prepared from the corresponding 1-sila- and 1-germacyclo-3-pentenes in two different ways. The method of synthesis and the chemical reactivity of this new class of heterobicyclic products are determined by the heteroatom and the alkyl or aryl substituent bonded to silicon or germanium.