α-Phenylselenenylation d'aldehydes - synthese simple d'α-cetoaldehydes a fonction cetone protegee

Morpholinophenylselenenamide $\text{2}$ add to β-phenylselenoenamines $\text{1a}$ and yield β,β-bis(phenylseleno) enamines $\text{4}$. These compound undergo hydrolysis to form bis(phenylseleno) ethanal $\text{5a}$. Also, $\text{2}$ react with enolic aldehydes to give α-phenylselenoaldehydes $\text{3}$. This reaction allow a “one step” synthesis of cetoselenoacetals $\text{5}$ of α-cetoaldehydes with good yields.     

Per - bicyclophosphoranylation d'alditols

Reaction of bicyclophosphane $\text{1}$ with glycol $\text{2}$, glycerol $\text{3}$, erythritol $\text{4}$, L(-)arabitol $\text{5}$ and dulcitol $\text{6}$ leads to the corresponding per-alkoxybicyclophosphoranes $\text{2p}$ - $\text{6p}$ which are in tautomeric equilibrium with the phosphates forms $\text{2p}$′ - $\text{6p}$′.The amount of these latters increases regularly from traces to 24%.     

Reactions d'addition du tetrahydrofuranne sur les F-alkyl ethylenes,F-alkyl acetylenes et F-alkyl propynoates d'ethyle

The thermal behaviour of F-alkyl éthenes 1, F-alkyl acetylenes 2 and ethyl 3-F-alkyl propynoates 3 in tetrahydrofuran solvent was investigated. In refluxing solvent, one THF unit, reacting at its α-site, was added to the terminal unsaturated carbon of 1 and 2, and to the carbon bearing the F-alkyl group of 3; the reaction is regiospecific. Moreover, the monoadducts produced from 2 and 3 showed a strong stereoselectivity, leading respectively to E 2-(1,2-dihydryl 1-F-alkenyl)tetrahydrofurans and E ethyl 3-F-alkyl 3-(2-tetrahydrofuryl)-propenoates as the main products ($\text{cis}$-addition of THF to 2 and $\text{trans}$-addition to 3).     

Structure d'un nouvel heteroside d'isoflavone: le sarothamnoside

The structure of sarothamnoside (genistein 7,4′-di-O-[4-O-β-D-glucopyranosyl-β-D-apiofuranoside]), a new isoflavone glycoside from $\text{Sarothamnus scoparius}$ and $\text{S}$, patens, has been established by spectral analysis, mainly ₁₃C NMR.     

Isomerisation thermique d'alkylidenecyclobutanones : Piegeage du diradical intermediaire par migration −1,5 d'hydrogene

The biradical intermediate which results from the thermal ring fission of alkylidene cyclobutanones $\text{2}$ serves as a common precursor of isomerised cyclobutanones $\text{3}$ (1,3 carbon shift), and of dienones $\text{4}$ by way of intramolecular 1,5 hydrogen shift.     

Reactivite ambidente de l'anion imidazolate vis-a-vis d'un electrophile aromatique

The reaction of 1,3,5-trinitrobenzene (TNB) with imidazolide ion (Im^-) provides the first example of the ambifunctional nucleophilic reactivity of this anion towards an aromatic electrophile. The N-adduct $\text{1}$ is formed under kinetic control but the C-adduct $\text{2}$ is the thermodynamically stable product. The N,C-diadduct $\text{3}$ is also observed.     

Synthese d'un isostere soufre de la prostaglandine A2

The synthesis of the title compound $\text{2a}$, a prostaglandin with a β-thiolactone ring is described, which involves the use of 2-tetrahydropyranthiol, an efficient reagent for introducing the sulfur atom.     

Ozonolyse d'olefines perfluorees

We have obtained unusually stable secondaxy ozonides ($\text{2a-c}$) by heating neat perfluoroalkenes ($\text{1a-c}$) with ozone.     

Synthese d'isoquinoleines F-alkyl substituees

In this paper we report preparation of isoquinolines F-alkyl substituted in $\text{1}$ position by R_F chains such as CF₃, C₃F₇, C₅F₁₁, C₇F₁₅. These compounds are obtained by catalytic deshydrogenation of the F-alkyl-1 dihydro-3,4 isoquinolines which are prepared by cyclodeshydratation of the N-(phenyl-2 ethyl) F-amides and N- (phenyl-2 propyl) F-amides. These last compounds are obtained the N-allyl F-amides by Friedel-Crafts type reaction.The preparations as a whole yield 26 new F-alkyl compounds.     

Synthese et proprietes d'un η5-phospholyl-cobalt-dicarbonyle

The reaction of phosgene with the anion 2,5-diphenylphospholyl gives 2,2′,5,5′-tetraphenylbiphospholyl. This compound reacts in boiling toluene with cobalt carbonyl to yield (η⁵-2,5-diphenylphospholyl)dicarbonylcobalt which shows no catalytic activity in the cyclooligomerization of acetylenes. It also reacts with bromine and alcohols to give 1-alkoxyphospholes. We have also fortuitously observed that the reaction of phenyllithium with 1,2,5-triphenylphosphole yielded a $\text{2.6}\text{1}$ mixture of 2,5-diphenyl- and 2,3,5-triphenyl-phospholyl anions.     

La lancéomigine,alcaloide d'un type nouveau

Lanceomigine $\text{3}$, which is the first of a new class of alkaloids and 17-hydroxypseudoakuammigine $\text{2}$ are described. Structure of $\text{2}$ and $\text{3}$ is based on their physical properties and on a chemical correlation. The reduction product of $\text{3}$ has been subjected to single crystal X-ray analysis.     

Reductions stereoselectives d'acetyl β-lactames

Trans acetyl β-lactam $\text{3}$ is stereoselectively reduced by different reagents to afford the corresponding trans erythro and/or trans threo alcohols $\text{4}$ and $\text{5}$.     

Nitroxydes 94 : decomposition thermique d'un radical oxazolidine-oxyle.

Pyrolysis of spiro ((4-t-butyl cyclohexane)-1,2′-(4′,4′-dimethyl oxazolidine-3′ oxyl)) $\text{1}$ leads to spiro ((4-t-butyl cyclohexane)-1,2′-(4′,4′ oxazolidine 3′-hydroxy)) $\text{2}$, 4-t-butyl cyclohexanone and 4-t-butyl cyclohexanoxime. Kinetic studies show that the reaction proceeds through an autocatalytic process.     

Decarboxylation catalytique et quantitative d'acides arylacetiques en presence'de cuivre I

Copper(I) salts of arylacetic acids $\text{1}$ RCO₂H readily undergo a catalytic and quantitative decarboxylation in acetonitrile leading to hydrocarbons $\text{2}$ RH when the corresponding carbanions R are stabilized by resonance and/or electronwithdrawing substituents.     

Preparation d'olefines trisubstituees bifonctionnelles par voie photochimique

∝-methyl ∝-functionalized (CO₂CH₃, CN, CH₂OH and CH₂Cl) cyclopentanones $\text{2}$ when irradiated by UV light give title compounds : 5-substituted 4-hexen 1-al $\text{4}$ as a mixture of E and Z isomers. A comparison of the photochemical behaviour of this cyclopentanones and a simple and efficient chemical transformation of the isomers Z in the more demanded isomers $\text{4}$ E are described.     

Synthese d'ynamines fonctionnalisees en β de la triple liaison et stereoselectivite de l'hydrolyse des cycloadduits formes avec la cyclopentenone et les lactones α-β insaturees

Ynamine 3 reacts with cyclopentenone and lactone $\text{5}$ by cycloaddition to afford adducts $\text{7}$ and $\text{4}$ the hydrolysis of which steroselectivity controlled. The presence of the alkoxy group in β position of the triple bond does not interfere neither with the process of cycloaddition nor the high stereoselectivity of the hydrolysis of cyclobutanone enamines annulated with a five or a six membered ring.     

Nouveaux trioxophosphetanes generateurs d'oxygene singulet a basse temperature

We have prepared phosphite ozonides $\text{1b}$–$\text{3b}$ which are efficient and clean singlet oxygene generators at low temperature.     

Etudes théoriques sur le mécanisme de formation d'un epoxyde à partir d'un métallocycle. L'étape de cycloréversion

Extended Hückel calculations of various intermediates for the reaction of olefins with MoO(O₂)₂L₂ confirm the viability of olefin coordination and metallocycle formation trans to the oxo ligand. Frontier orbital changes and couplings revelant to concerted elimination of epoxide from the metallocyclic unit $\text{MoOOCH}{}_2\text{C}$H₂ by a cycloreversion step reveal the importance, even in such polar systems, of the antarafacial alignment of the frontier orbitals.     

Synthèse,croissance cristalline,propriétés structurales et physiques d'un nouveau tungstate +V d'aluminium AlWO4

Aluminium tungstate (V) is isostructural with the monoclinic chromium doped M₂ variety of VO₂ (space group $\text{C 2}\text{m}$). In the rutile-like framework tungsten +V is stabilized by WW pairs. The structure is confirmed by diamagnetic and semiconductor behaviour; the activation energy measured on single crystal prepared by electrolytic reduction in an alumina crucible is 0,35 eV.     

Migration du carbonyle : Obtention d'homologues du glyoxal à fonction cétonique protégée

Substituted glyoxals with protected ketogroup $\text{3}$ were obtained by reaction of α-chloro-α-(aryl- or alkyl-thio)ketones $\text{1}$ with sodium methylate in methanol.