Synthèse d'alcools acétyléniques par alkylation d'hydroxy-ω-alkynes-1

Synthesis of acetylenic alcohols by alkylation of ω-hydroxy-1-alkynes In liquid ammonia and with lithium amide, the alkylation of an ω-hydroxyl-alkyne proceeds with good yield with primary or secondary alcohols and with fair yield with tertiary alcohols. It is a very convenient way to prepare many substituted acetylenic alcohols.     

Stéréosélectivité et régiosélectivité de la réduction des cyclopropènes-2,3 et méthylène-2 cyclopropanes fonctionalisés en position 1

Reduction of 2 cyclopropenyl esters and alcohols with lithium aluminium hydride is selective; at low temperatures (0°) the double bond is not reduced, but at higher temperatures (65°) the reduction is complete and only the cyclopropylmethanol is obtained. The reduction of the double bond is regioselective (the most stable carbanion is formed) and stereospecific (the hydride attack on the double bond occurs cis to the functional group). This stereospecificity can be explained through the initial formation of an alkoxylaluminium hydride followed by an intramolecular reduction of the double bond. Similar results have been obtained in the reduction of functionalised methylenecyclopropanes.     

Synthèse d'hétérocycles en catalyse par transfert de phase

A general study of the chemical behavior of heterocyclic anions, dianions and dianionic reagents under phase transfer catalysis conditions allowed us to synthesize various heterocyclic compounds such as imidazo[2,1-b]thiazole and derivatives; imidazo[2,1-b]thiazine and imidazo[2,1-b]benzothiazepine. Reaction conditions e.g., catalyst, solvent, temperature, etc., are indicated.     

Etude de la régiosélectivité de l'action des organozinciques sur les α-iminoesters issus de 2-amino ou 3-aminoalcools I. Synthése d'α-aminoesters polyfonctionnels

The preparation of some α-iminoesters R′N=CHCOO-t-C₄H₉ with R′ bearing an alcohol group has been studied; organozinc compounds prepared from allylic or propargylic bromides and from α-bromoesters or α-bromoamides react regiospecifically with these α-iminoesters to give polyfunctional α-aminoesters.     

Applications synthétiques de la cyclisation d'alcools tertiaires γ-éthyléniques en α-bromotétrahydrofurannes sous l'action du N-bromosuccinimide. I. Synthèse facile de la triméthyl-2,2,5-cycloheptène-4-one ou karahanaénone à partir du linalol

The ionic reaction of linalool and N-bromosuccinimide in CCl₄ at room temperature afforded 2-methyl-2-vinyl-5-(1-bromo-1-methyl-ethyl)-tetrahydrofuran (I). On treatment with refluxing collidine this compound yielded the intermediate allyl vinyl ether III, which immediatealy rearranged to 2,2, 5-trimethylcyclohept-4-en-one (V) or «karahanaenone» through a [3,3]-sigmatropic process. Karahanaenone, a constituent of hop oil, was thus synthesized for the first time (overall yield 62% from linalool). The mechanisms of these reactions are discussed.     

Synthèse de 2H -furo[3,4-b] (3H, 5H, 7H) pyrannediones-4,5. Acylation de (2H, 5H) furannediones-2,4 (acides tétroniques) par les chlorures d'acides α-éthyléniques

Direct acylation of tetronic acids by α,β-ethylenic acid chlorides with tin tetrachloride gave a new type of fused heterocyclic compounds: 2H-furo[3,4-b] pyran-4,5-diones. Acylation in alkaline medium gave enol esters which could be transposed in furopyrandiones. However, the first route was more satisfactory.     

Etude Stéréochimique par RMN 1H de Tetrahydropyrannes β-Chlorés α-Substitués

The ¹H NMR study of 2-alkyl-3-chlorotetrahydropyrans, obtained by reaction of Grignard reagents with a mixture of cis/trans-2,3-dichlorotetrahydropyrans, shows cis/trans configuration of two isomers in which the alkyl substituents are exclusively in the equatorial position. 3-Chloro-2-phenyltetrahydropyran exists in trans (eq-eq) configuration only. The ¹H NMR study of cis/trans 2-alkoxy (or aryloxy)-3-chlorotetrahydropyrans, obtained by reaction of alcohols or phenol with 2,3-dichlorotetrahydropyrans, shows the axial position of the alkoxy (or aryloxy) substituent.     

Effets stéréosélectifs dans les réactions des complexes métalliques. I. Stéréosélectivité de la réaction de l'anion D-N-(hydroxy-2-éthyl)-propylènediaminetriacétatoferrate (III) avec quelques dérivés d'acides aminés

A chromatographic method for studying small effects of ligand stereoselectivity in the formation of labile metal complexes has been developed. It is shown that unidentate ligands can react stereospecifically with labile optically active metal complexes. An anion-exchanger charged with an optically active form of Fe^III-N-(2-hydroxy-ethyl)-propylenediamine triacetate is used as a support in chromatography of N-acylated amino acids, and differences in retentions have been measured by elution and by frontal analysis.     

Synthèse de copolymères greffés à base de polyéthylène—1

Polyethylene macromolecular free radical initiators, obtained by ozonization, are used to prepare graft copolymers with methyl methacrylate, styrene and vinyl chloride. The reactions parameters are the number of initiator groups (found by DPPH), peroxide and hydroperoxide proportions (respectively 36 and 64%), decomposition rate (K_d at 90° 10⁻¹sec⁻¹) and monomer concentration. The molecular structure of these copolymers is defined.     

Hétérocyclisations intramoléculaires par réaction d'oxymercuration III. Régiosélectivité et stéréosélectivité de l'oxymercuration intramoléculaire de phénols orthoallyliques

The intramolecular heterocylization of ortho-allylic phenols by oxymercuration has been realized with compounds having different substituents on the allylic chain. In all cases, only the corresponding benzofuran is formed. However, with a substituent at the terminal carbon of the double bond, we also observed the formation of benzopyran. The influence of the solvent and the mercuric salt on the orientation of this reaction has been examined. There is evidence of a molecular rearrangement during the reduction.     

Photolyse stéréosélective des [α-tétrahydropyrannyloxy] -2 tétrahydropyrones-3

The photochemical irradiation of the 2-[sα-tetrahydropyrannyl-oxy]-3-tetrahydropyrones (3) gives the -3-tetrahydropyrone (6)and the α-valerolactone (7). the structures (S*, R*) or (S*, S*) which were determined by mmr and by comparison with the 2-[α-tetrahydropyrannyloxy]-2tetrahydropyrannes (5) (S*, R*) and (S*, S*) influence the rate of the photolysis     

Synthèse par cyclisation nucléophile de dérivés de sucres portant un hétérocycle inséré en spiro. Note de Laboratoire

Synthesis of Sugar Derivatives Bearing a Spiro Heterocycle via Nucleophilic Cyclization Treated with the 1,4-binucleophiles 1,2-diaminoethane, 2-aminoethanol, 2-aminoethanethiol, L -cysteine, o-phenylenediamine, o-aminophenol or o-aminothiophenol the ketosugar derivative 1 gave in good yields the corresponding spiro derivatives 2–8 . In each case, the reaction was stereospecific leading to the isomer bearing the N-atom on the endo face of the bicyclic starting material. Starting from the sugar enone 9 , the aromatic 1,4-binucleophiles led stereospecifically to the spirobenzo [b]-diazepine 10 , -oxazepine 11 or -thiazepine 12 . In one case, an imine (13) was isolated. As 13 cyclized to 6 , the intermediate formation of these kind of derivatives could be considered as a common step for all these reactions.     

Régiospécificité et stéréosélectivité de la cycloaddition de l'oxyde de benzonitrile sur les pyrazolines-3

Pursuing our study on the cycloaddition of benzonitrile oxide with Δ₃-pyrazolines (1,2), we can now affirm that this reaction is regiospecific and stereoselective. The behaviour in acidic medium was studied. We have then discussed the process of epimerization and degradation observed according to the C₄ substituent of the bicyclic molecule and the solvent used.     

Synthèse de sucres aminés ramifiés III. Synthèse et réactions de 1′α-amino-nitrile dérivé du di-O-isopropylidène-1,2:5,6-α-D-ribo-hexofurannosul-3-ose

The addition of cyanohydric acid to 1,2:5,6-di-O-isopropylidene-α-D -ribo-hexofurannos-3-ulose can be sterically controlled. Under kinetic conditions, the allo cyanohydrine epimer is formed, under thermodynamic conditions, the gluco epimer is formed. The configuration of these two products is proved by their chemical reactions. Hydration followed by hydrolysis of the nitrile group of the allo epimer (O-acetyl derivative) gives the 3-C-carboxy-1,2-O-isopropyloidene compound. This product forms the corresponding γ or δ-lactone with hydroxyl ( 5 ) or ( 6 ). On the other hand, after hydrolysis of 5,6-isopropylidene, the 3-O-acetyl derivative of the gluco epimer gives an acetyl migration from position 3 to position 5 and finally to position 6. By reaction of the allo epimer with NH₃ and CN^?, an aminonitrile is formed. The allo configuration is deduced from the above mentioned reaction and from IR. and NMR. data. Several acetylated and trifluoracetylated derivatives of these products are described. The oxidation of the nitrile group to the amide group is possible with both epimeric cyanohydrines and the amino-nitrile.     

Synthèse de composés comportant deux hétérocycles oxygénés accoles au noyau benzénique, éthers du résorcinol

We wish to report the preparation of new bisheterocyclic compounds derived from resoreinol. We tried to sue methods during this investigation which would be selective and afford only tricyclic linear compounds. The starting material was resorcinol or the monomethylether of resorcinol. By reaction with chloroacetonitrile, acrylonitrile or ethyl chlorobutanoate, we obtained the intermediate compounds which were then cyclized by reaction with sodium acetate or polyphosphoric acid; either a catalytic reduction or treatment with zinc in presence of hydrochloric acid furnished the heterocyclic base. Another condensation followed by a cyclization and a reduction gave the desired compounds.     

Influence des propriétés intrinsèques de ligands calixaréniques sur des réactions de transformation catalytique de l'éthylène

Influence of the intrinsic properties of calixarene ligands on catalytic reactions involving ethylene. This review shows how the particular structural and chemical properties of calix[4]arene-derived ligands can be exploited in the catalytic transformation of ethylene into dimers, oligomers, and polymers.     

Synthèse de triazolo-1,2,3 nucléosides par cycloaddition entre azotures de glycosyle et acétyléniques ativés

This paper deals with a new method of preparation of glycosyl azides on which the cycloaddition of activated acetylenic compounds, in an improved manner, yields 1,2,3-triazolonucleosides. This has been done in the allo-, ribo- and arabinofuranoses and mannopyranose series with methyl propiolate and ethyl acetylenedicarboxylate.     

Synthèse de nouveaux alkyl-2 et -3 tétrahydrofurannes et -pyrannes

New 2- and 3-alkyltetrahydrofurans or -pyrans were synthesized by various methods which can be extended to a larger series. These compounds include tertiary and quaternary α carbon substituted heterocycles, a very few of which were already known.     

Synthèse et stéréochimie de perhydrocyclopenta[b]furannones-3-cis et perhydrocyclopenta[b]furannols-3-cis

Synthetic route to new cis-perhydrocyclopenta[b]furan-3-ones and cis-perhydrocyclopenta[b]furan-3-ols is described. Their configurations and conformations were inferred by ¹H and ¹³C nmr spectroscopy. A certain rigidity is associated with the bond common to the two fused ring. The conformation of tetrahydrofuran-3-one ring appears to be a composite of the C, and C₂ forms depending on the C-2 substitution.