Sur la reaction de reformatsky. Preparation et reactivite de l'organozincique issu du sel bromozincique de l'acide γ-bromocrotonique

The condensation of aldehydes and ketones with the bronozinc salt derived from γ-bromocrotonic acid, in the presence of zinc, yield to the “linear” and “branched” unsaturated hydroxyacids. These latters, which represent the cinetic products of the reaction, equilibrate at the alcoolate state to give, after hydrolysis, the “linear” compounds.     

Preparation et reactivite de fluorovinylzincs

Several fluorovinylzincs have been prepared. Palladium catalyzed cross coupling reactions give stereoselectively fluorinated compounds.     

Preparation et reactivite de quelques enynes fluores

Several fluoroenynes have been prepared by palladium—catalysed cross coupling reactions.     

Synthese et reactivite d''organometalliques perfluores. VII [1] reactivite comparee de derives perfluoroalkyles satures et insatures de l''etain et du mercure vis-a-vis d''electrophiles.

The reactivity of some derivatives of perfluorooctenyl-tin, perfluorooctenyl-mercury and perfluorooctyl-mercury towards protic acids, especially hydrogen chloride, is studied.

The easy cleavage of the tin - sp² carbon bond is painted out, and used to study possibilities of transferring the perfluorooctenyl radical on mercury, upon reaction with mercuric salts.

The mercury-perfluoroalkyl radical bond is shown to be, on the contrary, very resistant to an electrophilic attack.

These results are compared to those concerning the hydrocarbon analogs, and an interpretation, relied to the electronic density on the carbon atom bound to the metallic atom, is given.     

Synthese et reactivite d'un complexe diene-fertricarbonyle derive du phenyl-1-dimethyl-3,4-phosphole

The complex (DMPP)Fe₂(CO)₇ in which DMPP (1-phenyl-3,4-dimethylphosphole) is η⁴-coordinated with Fe(CO)₃ through its diene and η¹-coordinated with Fe(CO)₄ through its phosphorus atom is selectively decomplexed at phosphorus to give (DMPP)Fe(CO)₃ by reaction with AlCl₃ followed by NH₄OH. This new η⁴-complex (DMPP)Fe(CO)₃ can be oxidized, sulfurized and quaternized at phosphorus by H₂O₂, S₈, and PhCH₂Br and MeI, respectively, as an ordinary phosphine without decomplexation of the diene. As a free phosphole, this complex also gives a ring-expanded product by reaction with benzoyl chloride, water and Et₃N. In the presence of some metallic salts such as (PhCN)₂PdCl₂, it loses CO to give the bimetallic sandwich [(DMPP)Fe(CO)₂]₂. It can also give some new bimetallic complexes such as [(DMPP)Fe(CO)₃]W(CO)₅ by complexation of the phosphorus lone pair by W(CO)₅(THF).     

Sur la reactivite du squarate de dimethyle vis-a-vis de thiols.

Thiols react with dimethylsquarate according to a 1,2- or 1,4 addition process, leading to new 2-hydroxy-2 S-alkyl-3,4 dimethoxy-3 cyclobutenones.     

Preparation de β-cetonitriles via l'acylation du cyanacetate de trimethylsilyle par les anhydrides mixtes.

β-ketonitriles R¹COCH₂CN and R¹COCH(R²)CN are respectively prepared from (CH₃)₃SiOCOCHLiCN or R²CHLiCN by acylation reaction with mixed anhydrides RCOOCO₂Et.     

Chimie des complexes de metaux de transition avec des hydrocarbures cyanes : III. Quelques observations sur la conformation et la reactivite de complexes dicyclopentadienyles du molybdene et du tungstene

A new class of cyclic telluronium salts has been prepared. All the salts are stable in solution in CHCl₃ or dimethylsulphoxide (DMSO). Conductivity measurements in DMSO and dimethylformamide (DMF) have shown that considerable ion pairing occurs in solution. Infrared, ¹H, ¹³C, ¹²⁵Te NMR, and mass spectra are reported and discussed.     

Accroissement de la reactivite des phosphorines en tant que dienes et philodienes par complexation du phosphore

The 2-Phenyl-4,5-dimethylphosphorin P-W(CO)₅ complex reacts easily as a dienophile with 2,3-dimethylbutadiene through its 1,6-positions and as a diene with N-phenylmaleimide, dimethyl acetylenedicarboxylate and cyclopentadiene, through its 1,4-positions.     

Enolates de l'acetylacetate d'ethyle. Structure et reactivite du sel de potassium en presence d'ether couronne et de cryptand

It is shown that, through the addition of 18-crown-6 or cryptand (2.2.2) to potassium ethyl acetoacetate enolate solutions in tetrahydrofuran, 1:1 complexes are formed. A single crystal of the 1:1 potassium énolate-18-crown-6 complex has been obtained. Its structure has been determined by X-ray diffraction. The crystal includes entities formed from an enolate anion chelating a potassium cation externally complexed by the crown-ether. The vibrational spectrometry shows that the structure of the entity is kept in solution. In the species formed through the addition of cryptand (2.2.2), the enolate anion has a structure (IR spectroscopy) and a reactivity very close to that of the free anion, observed in a dissociating solvent (DMSO, HMPA). When crown ether is added, a contact ion pair is formed, in which the cation is externally solvated by the crown. On the other hand, the cation encapsulation by the cryptand leads to a released anion with an “ S-trans” or “W” structure. The reactivity and the orientation of the alkylation reactions of these entities have been measured in THF solutions. They are discussed in relation to the structure of the species present in the reaction medium.     

Synthese,caracterisation et reactivite de polymeres porteurs de fonctions chloroformiates

Chemical modification of low molecular weight polymers having functional groups along the chain, can lead to new macromolecular compounds which direct synthesis cannot be studied by classical polymerization ways. Synthesis of polymers possessing chloroformate groups has been obtained by a double modification reaction of polydienes backbones. Reactivity of new functions has been used for fixation of various organic compounds on the macromolecular chain. On the resulting polymers, the organic products are linked by carbonate, urethane or thiolcarbonate bounds varying with the nature of starting molecules: alcohol, amine or thiol which has reacted on the chloroformate groups.     

Etude de la reactivite du tris(tertiobutyl)phenyldithiophosphorane

Heating of tris(tertiobutyl)phenyldithiophosphorane gives rise to an isomer with a tetracoordinated phosphorus atom. The action of triphenylphosphine loads to a tricyclophosphathiane which can be transformed in diphosphene by an excess of triphenylphosphine. Reactions with various nucleophilic derivatives (pyridine, triethylamine, diethylamine, butylamine, water, tetraphenylarsonium chloride) are described.     

Stabilisation de molecules hyperactives par complexation: Le formyl-2 butadiene fer-tricarbonyle. Preparation,dedoublement et reactivite

The stable dieneiron tricarbonyl complex of the unstable 2-formylbutadiene was prepared from isoprene by two different ways and resolved via chiral semioxamazone formation. The complex reacts easily with Grignard or other carbanionic reagents leading to the corresponding alcohols from which the stable diene alcohols can now be obtained by decomplexation. The reaction of the aldehyde complex proceeds nearly diastereospecifically with organolithium compounds and cuprates, these reagents showing an inversed diastereoselection. This contrasts with the behaviour of magnesium and titanium derivatives which lead only to mixtures of those diastereoisomers. Wittig and Horner-Emmons olefinations were also studied in order to examine the diastereoselectivity of the subsequent diazoalkane cycloaddition and the possibility for synthesis of Ips-type insect pheromones via hydroboration.     

Synthese et reactivite d'organomagnesiens perfluores. V.[1] Synthese et identification de nouveaux composes perfluoroalkyles du mercure a chaine longue.

The reaction of mercuric salts HgY₂ or organic mercuric compounds R_HHgX with long chain perfluorinated Grignard reagents R_FMgBr leads to a series of new perfluoroalkyl mercury derivatives with the general formula R_FHgZ (R_F=C₄F₉, C₆F₁₃, C₈F₁₇ ; Z=R_F,R_H,Y with Y = I,Br,Cl, NO₃,OCOCH₃,OCOCF₃).The synthesis of these organomercuric compounds is described, and their spectroscopic properties are reported.     

Ions α-cétocarbenium : Influence de la nature de la fonction carbonyle sur la reactivite des ions α-ceto 4-t.Bu cyclohexylcarbenium

α-keto 4-t.Bu cyclohexylcarbenium ions formed by AgSbF₆-CH₂Cl₂ dehalogenation of α-keto 1-bromo 4-t.Bu cyclohexanes, give the corresponding α-ethylenic carbonyl compounds and bicyclic oxonium salts. The ratio of products does not vary according to the electronic environment of the carbonyl function but depends on the size of the adjacent group, suggesting that the α-ketocarbenium ion conformation determines the product ratio.