Syntheses d'oxazolidines substituees par l'adamantane et de nitroxydes oxazolidines stables derives de l'adamantane

Adamantane oxazolidine derivatives have been prepared. The corresponding mono and biradicals have molecular shapes well suited to the study of the motion anisotropy in solution.     

Synthese photochimique et etude structurale d'alcoxy-spirocetals et de trioxa-bis-spirocetals

The spiroketal systems can be obtained easily by a Norrish type II reaction applied to tetrahydropyranic ketoacetals having a carbonyl group in δ position of the acetalic hydrogen. The structures of spirans and bispirans established by IR, NMR (¹H and ¹³C show an axial conformation for the C-O bond of the tetrahydrofuran ring. With the bispirans this anomeric effect requires for some isomers a twist boat conformation of the tetrahydropyran ring.     

Hydrogenation asymetrique de precurseurs d'aminoacides a l'aide de mono- et diphosphines derivees de sucres

Mono- and di-phosphines derived from sugars are synthesized and used as ligands in asymmetric catalysis. In the presence of a base (triethylamine, KOH…) the cationic complex [Rh(COD)dioxop]⁺ClO₄^?, catalyzes reduction of α-amino acid precursors with high optical yields (78–86%). The influence of the base is discussed.     

Synthese et etude par resonance magnetique nucleaire du carbone 13 et de l'etain 119 d'une serie de triorganostannyl-2 butanes

Optically active triorgano-2-stannylbutanes have been synthetized by different methods, one being the direct substitution of optically active s-butyl halides with triorganostannyl alkali metals. This route involves a complete or partial inversion of configuration at the chiral carbon atom. Carbon-13 and tin-119 NMR data are reported as support for the identification of eight triorgano-2-stannylbutanes. The special case of tetra(2-butyl)tin, with four identical chiral centres has been examined.     

Synthese d'analogues tetrazoles de l'acide phosphonoacetique

Several routes to 5-(phosphonomethyl)-1(H)-tetrazole, a new antiviral agent, have been investigated.     

Synthese et configuration de l'alnincanone

Alnincanone 1, and its three diastereoisomers at C-20 and C-24, have been synthesized from dipterocarpol. The configuration of the four isomers has been defined by several independent methods; the naturally occurring alnincanone is 20S,24R.     

Synthese d'alkenyl et de cycloalkenyl polyflones

A method of synthesis of alkenyl and cycloalkenyl polyflones is described. It involves the reaction of a perfluoro or polyfluoro organometallic compound with an α-chloro alkyl or cycloalkyl thiocyanate. The obtained sulfide is oxidized into sulfone with m-chloro-perbenzoïc acid. Then this sulfone is transformed into vinylpolyflone by dehydrochloration.     

Dosage de l'hydrogene,de l'azote et de l'oxygene dans le monocarbure d'uranium

A method is described for the determination of hydrogen, oxygen and nitrogen in uranium monocarbide. Hydrogen and oxygen are determined by the classical or modified “Platinum flux” method at 2000° with a coefficient of variation of 10%. Nitrogen is determined at 2000° by the modification of the “Platinum flux” technique. The results obtained are in agreement with those found by Kjeldahl analysis. The coefficient of variation is about 10%. A procedure for the simultaneous determination of the 3 gases is given.     

Sinthese de copolymeres sequences de l'acetate de vinyle et de l'acrylate d'ethyle par telomerisation

A new two-step procedure for the synthesis of ethyl acrylate - vinyl acetate block copolymers is described : the first stage is the telomerisation of ethyl acrylate with carbon tetrachloride by redox catalysis, the second being another telomerisation of vinyl acetate, using the trichloromethyl end group of the first block as the telogen agent, with peroxydic initiation.     

Synthese d'acetals de cyclopentanones halogenees et deuteriees

Acetals of halogenocyclopentanones are formed in good yield from 5-chlorocyclopentenones. Their structures and stereochemistry are assigned on the basis of ¹H NMR data and confirmed by a method based on selective deuteriation. Chemical shifts and coupling constants are listed.     

Application de la G.P.C. a l'etude de la distribution moleculaire de polyesters non-lineaires

Molecular distribution of stoichiometric copolycondensate trimethylolpropane/azelaïc acid with conversion is investigated. Weight fractions of the first oligomers determined by G.P.C. agree with theoretical forecasts.     

Synthese stereo et enantioselective par l'intermediare de complexes du fer de derives chrysanthemiques dieniques et d'aldehydes hemicaroniques cis et trans.

A stereo and enantioselective synthesis of cis and trans hemicaronic aldehydes, starting from the optically active sorbic aldehyde-irontricarbonyl comples, is described.