Reaction d'aminomercuration—xv: Aminomercuration d'olefines par les amines aromatiques en milieu aqueux

Aminomercuration of double bond by aromatic amines is easily performed by using an aqueous solvent. No oxymercuratio occurs. The reaction is general, regiospeciflc with terminal olefins. This specific feature of aromatic amines is due to a preliminary ring mercuration whose effect is to destroy the preformed amine/mercuric salt complex preventing the reaction.     

Phénylation d'alcools allyliques acycliques : II. Regioselectivite du transfert d'hydrogene

PdCl₂, HNaCO₃-catalysed phenylation of deuterium-labelled allylic butenols, a Heck type reaction, proceeds by a highly regioselective 1,2-hydrogen shift $\text{via}$ a Wacker type intermediate. No decomplexed enol was formed during this reaction.     

Recherches en serie azabenzodiazepine—VIII : Hydrazinolyses d'azabenzodiazepinones et d'azabenzodiazepinethiones de type 1,5

The action of hydrazine on several azabenzo-1,5-diazepinones gives 3(5)-methyl-5(3) pyrazole and the corresponding heterocyclic diamines but the reaction with phenylhydrazine is more complicated and depends on the nature of the heterocycle attached to the seven member ring. In this case two reaction centres must be taken into account; the amide group and the carbon atom in the 6 position. According to experimental conditions hydrazinolysis of s-triazolotriazepinethiones and pyrazolodiazepinethiones give either 5-hydrazino s-triazolotriaze-pines or pyrazolylamino-triazole (or pyrazole) or 3-hydrazinopyrazoles and 3,4-diamino triazole. The mechanism suggested is addition of molecules of hydrazine in the 5 position followed by a transannular reaction to the 7 position.     

Stereochimie d'heterocycles du groupe IVB—II : Syntheses stereoselectives d'hydrogeno-1 et d'alkyl-1 sila-1 cyclobutanes

The reaction between n-butyllithium and 1,2 (or 1,3)-dimethyl-1-t-butoxy-1-silacyclobutanes proceeds with retention of configuration at silicon, and yields 10/90 (or 80/20) Z/E mixture of 1,2 (or 1,3)-dimethyl-1-n-butyl-1-silacyclobutanes. Methylation of 2 (or 3)-methyl-1-t-butoxy-1-silacyclobutanes (Z/E = 15/85 or 65/35) by methylmagnesium iodide gives 15/85 (or 65/35) Z/E mixture of 1,2 (or 1,3)-dimethyl-1-silacyclobutanes. The proposed configurations for substituted silacyclobutanes are supported by spectroscopic data (RMN) and chemical results (correlation of configuration and stereomutation of hydrogenosilacyclobutanes).     

Voie d'acces aux benzylidene-1 cyclohexadiene-2,4 fer tri-carbonyle et autres composes apparentes. Stabilisation singuliere d'une forme tautomere d'un aromatique

2,4-Cyclohexadien-1-yldimethylphenylphosphonium tetrafluoroborate obtained from the reaction of 2,4-cyclohexadien-1-yltricarbonyliron with PMe₂Ph in 96% yield, reacts readily with benzaldehyde in the presence of base to give 1-benzylidiene-2,4-cyclohexadienetricarbonyliron in 90% yield; this and other related reactions provide the first examples of the Wittig reaction adjacent to a tricarbonyl moiety.     

Metathese d'acetates d'alcools ω-insatures : Synthese de pheromones d'insectes

Esters of alkenoic acids, including insect pheromones as examples, have been synthesized using alkene metathesis reactions.     

Hydroboration d'amines insaturees: III - Reactions anormales d'hydroboration-alkylation d'amines propargyliques bromees

By hydroboration-alkylation of brominated propargylamines, we obtain brominated ethylenic amines and not the expected ethylenic amines with thexylalkylboranes. The thexyl group shows, in all cases, an anomalous high migratory aptitude.     

Regioselectivite sous controle d'interactions de charges ou d'interactions orbitalaires : Reaction d'anions α-chlores a charge localisee ou delocalisee sur des α-enones

Benzalacetophenone reacts with anions derived from methyl chloroacetate and chloroacetonitrile (which are of the charge-localized type) at the carbonyl group to give α-epoxyalkenes. In contrast, the same ketone reacts with the anions derived from methyl phenylchloroacetate and phenylchloroacetonitrile (the negative charge of which is delocalized) to give cyclopropanes by attack at the carbon-carbon double bond. These results support the hypothesis that the reaction is charge-controlled with the former two reagents and orbital-controlled in the case of the latter two. Only one cyclopropane stereoisomer is formed in HMPA.     

Etude des aldimines lithiees : III. Action des epoxydes et synthese d'amino-2 et d'hydroxy-2 tetrahydrofurannes

The reaction of lithiated aldimines, prepared from activated amides, with epoxides leads to good yields of 2-aminotetrahydrofurans (neutral hydrolysis) and 2-hydroxytetrahydrofurans (acid hydrolysis). Various epoxides were examined.     

Oxydation photochimique d'amines tertiaires et d'alcaloïdes—X : Introduction d'un groupement fonctionnel en α de l'azote nb de la yohimbine par oxydation photosensibilisee

Dye-sensitized photooxidation of the imino-ether 5, prepared from yohimbine 1a, led to the α-amino nitrile 9a when the reaction was performed in the presence of oxygen and KCN. Derivative 9a was hydrolyzed to the amide 9b, the transformation of which to carboxamido-5β-yohimbine 15 was studied.     

Dependance conformationnelle de l'effet isotopique dans les reactions d'addition nucleophiles : Influence du sens d'attaque sur la variation du terme hyperconjugatif

The secondary kinetic deuterium isotope effects measured in addition reactions of sulfite and borohydride ions has confirmed the importance of the hyperconjugative factor. Semi-quantitative evaluation of this stabilizing factor by calculating the orbital overlap evolution during reaction shows that the hyperconjugative contribution to the isotope effect is much more important during equatorial attack than during axial attack. This explains why isotope effects are similar for the additions, though their directions of attack are opposite and their transition states located differently along the reaction coordinate.     

Spirophosphoranylation d'α-aminoacides—I : Preparation et tautomerie

New spirophosphoranes have been prepared by reaction of &alpha-aminoacids with tricoordinate phosphorus substrates. In one case, 1i, an equilibrium chain-cycle P^IIIP^v has been observed.     

Hydroboration d'amines insaturees: V. Nouvelle voie d'access aux aminoalkylidenecycloalkanes

Hydroboration of various 1-bromopropargylamines by borinane and 3,6-dimethylborepane has led to α-bromovinylboranes. Treatment of these compounds with iodine in basic media, only gives aminoalkylidenecycloalkanes with excellent yields.     

Condensation du cyanoacetate d'éthyle sodé sur les sels d'iminoethers cycliques synthese directe de dérivés d'oxazepine-1,4 one-7

Sodium ethylcyanoacetate was found to react exclusively at the 2-position of trifluoromethanesulfonate 2-alkyl(aryl) 1,3-oxazolinium salts 2. In most cases, the reaction leads specifically to a new series of 5-alkyl(aryl) 6-cyano 2,3-dihydro 1,4-oxazepine 7-ones 3. This efficient one-step ring-enlargement process occurs at the oxazolidine stage. Structural parameters affecting the scope and limitations of this condensation are discussed.     

Sels d'alkyloxyphosphonium—XVI: Activation de l'hydroxyle anomere des 2,3,4,6 tetra-o-acyl-d-mannopyranoses

The joint action of tris(dimethylamino)phosphine-carbon tetrachloride on a tetra-O-acyl-2,3,4,6-d-mannopyranose leads to one α anomeric oxyphosphonium chloride (ATDP salt). This salt is not isolable, but decomposes to yield an anomeric mixture of 1-chloro derivatives. The reaction with alcohols give rise to the formation of orthoesters while thiophenol reacts to yield only the β-thiomannoside. These results are discussed and interpreted.     

Sels d'atdp—19: Cinetique de decomposition d'un chlorure d'atdp en chlorure d'alkyle et HMPT. Effet de solvant et effet de sel

The kinetics of decomposition of the 2-methyl-1-pentyloxy(trisdimethylamino)phosphonium chloride, was measured in several solvents. The experimental kinetic order towards the chloride anion was in the range from 2, in a dissociating solvent, to 1 in non dissociating solvents. Hence we afford experimental confirmation of an earlier prevision in the literature. A linear correlation of log k with the dielectric constants of the solvents was found in the case of the systems exhibiting first order kinetics, contrasting with the classical correlation in $\text{1}\text{?}$, generally observed for the reactions between ions of opposite charge. The salt effect has been measured and interpreted. It allows the performance of kinetic runs for non hindered, very labile ATDP salts, by their replacement by a mixture of an ATDP perchlorate and an aryloxyphosphonium chloride, both of which are stable.     

Stereochimie de la des benzoates d'argent sur des diesters iododesoxy ns: I- Action des benzoates d'argent sur des di-o-aroyl-1,2 iododesoxy-3 ns-glycerols

The stereochemistry of the reaction of silver benzoates on chiral di-O-aroyl-1,2 iododeoxy-3-sn-glycerols has been reinvestigated. The reaction proceeds either with or without neighbouring group participation, depending on : - possible electrophilic assistance by the silver ion to the ionisation of the substrate (occuring only with dissociated silver salts), - ability of substituants R¹ and R² on the substrates to stabilize a positive charge. Rearrangements are at minimum with R¹ and R² electronreleasing groups in the substrate, silver salts un-or weakly dissociated and bearing a good nucleophile. For one case, a regio- and stereo specific reaction is observed.     

Stereochimie et mecanisme de l'ouverture par les amines d'ions N-alcoxypyridinium : Formation competitive d'un ylure endocyclique; application a une nouvelle conversion heterocyclique

The N-alkoxypyridinium salt 1, with pyrrolidine, piperidine and diethylamine, undergoes reversible ring opening in acetonitrile. This competes with irreversible cyclization of an ylide to the bicyclic intermediate 3 which suffers subsequent ring opening to 3-ω-aminobutadienylisoxazol-4 ones in methanol. The different courses of the reaction is tentantively explained by means of HSAB theory. Stereochemistry of the primary open products is consistent with a disrotatory ring opening of cis-dihydropyridine adducts resulting from amine addition to the salt 1 or to the bicyclic ion 3. These primary products are further isomerized and all-trans structures have been isolated in the case of isoxazoline derivatives. Conversion of an N-alkoxypyridinium salt to substituted butadienylisoxazolones exemplifies a new type of heterocyclic ring transformation that can be described by the PARC-ANRO sequence: Proton Abstraction, Ring Closure—Addition of a Nucleophile, and Ring Opening.     

Quelques aspects du mecanisme de l'oxydation anodique de quelques halogenures d'adamantyl-2

For the anodic oxidation in acetonitrile of some 2-adamantyl halides, the distribution of reaction products is dependent upon the halogen and substitution at the bridgehead positions. Iodides gave exclusively 2-adamantyl acetamides. 2-Chloroadamantane yields to chloroadamantyl acetamides. From bromides both 2-adamantyl acetamides and bromoadamantyl acetamides are formed. Part of the reaction products obtained with 2-fluoroadamantane are formed from the cleavage of C₂F bond; this result is explained by analogy with the mass spectrometric fragmentation behavior of this compound. A general reaction mechanism covering all our experimental results is proposed.