Recherches sur le benzofuranne. LVI. Synthèses dans la série de l'Euparone par acétylation de benzofurannes acétylés et méthoxylés sur l'homocycle

Unsubstituted benzofuran derivatives acetylatcd and methoxy-lated on the benzenoid moiety can be further acetvlated either on the benzene or on the furan ring - with or without demethylation depending upon the different cases. A series of new isomers of Euparone (2,5-diacetyl-6-hydroxybenzofuran) and its corresponding ether has thus been formed.     

Préparation de dérivés de sucres acétyléniques terminaux et d'acides ynuroniques par réaction de Wittig. Note de laboratoire

Synthesis of Terminal Acetylenic Sugars Derivatives and Ynuronic Acids Derivatives by Use of a Wittig Reaction The method described for the preparation of terminal acetylenic sugars presents two advantages over earlier procedures: no new asymmetric center is created and the chain can be extended by one or more C-atoms. The method also allows preparation of ynuronic acids. The aldehydosugars derivatives 1–7 gave in good to excellent yields the corresponding gem-dibromoenoses 8–14 from which either the terminal acetylenic sugars derivatives 15–21 or the ynuronic acids 22–24 were easily prepared. A few examples of 1,3-dipolar cycloadditions (leading to 28–30 ) with these acetylenic sugar derivatives are also described.     

Sur le mécanisme de la réaction de meth-cohn-tarnowski de préparation des thiocoumarines

Reaction of 2-t-butylthiobenzaldehyde with N-(2-dialkylaminoethyl)-cyanacetamides followed by heating of the resulting 3-(2-t-butylthiophenyl)-2-cyanoacrylamides in polyphosphoric acid leads to the formation of 3-carboxamido-2-imino-2H-benzo[b][l]thiopyrann intermediates which afford thiocoumarins on hydrolysis. The authors postulate the intermediate formation of a thiophenate ion by an electronic mechanism involving six centers.     

Nouvelle méthode de préparation d'éthers vinyliques à partir d'acétals

A new way to vinylic ethers from acetals Acetals react at low temperatures in presence of a Lewis acid (aluminium chloride or magnesium bromide) with tertiary amine to give in good yields the vinylic ethers corresponding to the elimination of one molecule of alcohol.     

C-Glycosides,IV. Mise en évidence d'un mécanisme concurrent de la cyclo-addition dipolaire-1,3 concertée lors de la réaction d'une azométhine-imine avec un dipolarophile acétylénique. Communication préliminaire

The reaction of a glycosyl-azomethine imine with an acetylenic dipolarophile in the usual conditions for 1, 3-dipolar cycloaddition led to an α-ethynyl-hydrazone beside the ‘normal’ product of the reaction, i.e. the corresponding pyrazole. Deuteration experiments indicated that the two products are formed by two concurrent independent pathways. It is supposed that the slow step in the formation of the α-acetylenic hydrazone is the ionization of the alcyne whose conjugated base reacts rapidly with the 1, 3-dipole.     

Alkylation en catalyse par transfert de phase d'une série d'acridanone-9 substituées: Compétition entre O- et N-alkylation

Substituted acridanones were alkylated under phase transfer catalysis conditions. In so doing, a mixture of O- and N-alkyl derivatives was prepared. Orientation of the reaction products depends upon the alkylating agent but not on the position of the substituent. Hence, HSAB principles can explain this orientation.     

Recherches dans la série de la quinoléine: Préparation et oxydation du chlorhydrate de (1-quinoléinio)acétate

Reaction of quinoline with chloroacetic acid yields N-carboxymethyl-quinolinium chloride ( 1 ) (75%), which is oxidised by K₃Fe(CN)₆ in the presence of a base to N-carboxymethyl- 2 -quinolone ( 2 ) (70%). If 2 is heated in pure form at 300°, 1,3-Bis(2-quinolon-1-yl)acetone ( 4 ) (43%) is obtained; the expected N-methyl-2-quinolone ( 5 ) is formed by decarboxylation of 2 in benzyl benzoate at 275° (34%).     

Réarrangements 1,3 en série hétérocyclicque. II. Synthese d'alcoxy-5 et aryloxy-5 phényl-2 oxadiazoles-1,3,4

The 5-Chloro-2-Phenyl-1,3,4-oxadiazole has been prepared in fair yield. This product is a convenient starting material for the synthesis of O-alkylated or O-arylated derivatives of the 5-hydroxy-2-phenyl-1,3,4-oxadiazole.     

Action du phényllithium en série pyrazine: Piégeage des intermédiaires réactionnels par le benzoate de méthyle

The action of phenyllithium on pyrazine, 2-methyl pyrazine and acetonyl pyrazine gave mono- or di-addition products with azomethines bonds of pyrazine. The adducts can be condensed with methyl benzoate to give C or N condensed derivatives. No product with initial metalation of methyl or acetonyl groups was observed.     

Synthèse et étude physico-chimique de sulfures,sulfoxydes et sulfones en série thiazolique

The alkylation of Δ⁴-thiazoline-2-thiones under phase transfer catalysis conditions leads to the corresponding thioethers in good yields. The oxidation of 2-alkylthiazoles with m-chloroperbenzoic acid leads to the corresponding sulfines or sulfones depending on experimental conditions in yields of about 80-90%. The characteristic gle, tlc, ir, ¹H nmr and ms data are reported for most of the compounds studied.     

Recherches dans la série des cyclitols,XL. Préparation de cyclopentane-triols et de cyclopentène-triols et -diols

Two as yet unknown cyclopentene-triols have been prepared. The replacement of the halogen of cyclopentene derivatives brominated in the allylic position has been investigated. In the presence of dimethyl sulfoxide and sodium hydrogen carbonate, the bromine of some of the above mentioned allylic derivatives or the tosyloxy group of a dibenzoyloxy-monotosyloxy-cyclopentane derivative is replaced by a hydroxyl group without formation of any keto compound. The mechanism of action of the substitution agents is discussed.     

Recherches dans la série des cyclitols XLII. Synthèses de cyclitols tout-cis dérivés du cyclopentane; préparation des cyclopentane-tétrol et - pentol tout-cis

All-cis cyclitols derived from cyclopentane have been prepared in two ways: (i) by LiAlH₄ reduction of all-cis epoxypolyos; (ii) by dimethyl sulfoxide treatment, in the presence of sodium hydrogencarbonate, of brominated derivatives containing a neighbouring benzoyloxy group; under these conditions, the halogen is replaced by a cis-oriented hydroxyl group. Thus all-cis cyclopentane-tetrol and -pentol have been prepared; their configuration has been confirmed by NMR. spectroscopy.     

Indice de liaison en méthode CNDO. Relation entre indice de liaison et distance de liaison

The use of p_AB = Σ_μ^A Σ_ν^B _μν S_μν as bond index in the CNDO approximation is theoretically justified as it is an elaborated form of Coulson's bond order and an approximation of Roby's shared electron density. This bond index correlates with diatomic energy E_AB, a measure of binding energy, and with interatomic distance R_AB, for several bonds involving hydrogen and atoms of the n = 2 period. As an example of utilization of p_AB bond lengths in butadiene and a series of ethylenic compounds are determined.     

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.     

Etude de l'acylation de l'acétyl-3 acétoxy-8 indolizine par action de chlorures d'acide en présence de chlorure d'aluminium

Study of acylation of 3-acetyl-8-acetoxyindolizine by miscellaneous acid chlorides in the presence of aluminium chloride shows that this reaction is either limited to a transesterification (in the case of benzoyl chloride) or leads to introduction of an acyl group in position 1 with simultaneous liberation of the phenol function in position 8. When acylation takes place, acetyl chloride resulting from the cleavage of the acetoxy group competes with the acid chloride used in the reaction. Predominant acylation by the latter is observed when the reaction is performed with ethoxalyl chloride or with non branched aliphatic acid chlorides; by contrast solely acetylation takes place when pivaloyl or phenylacetyl chloride is used. These results are tentatively explained by a process related to the Fries rearrangement. The hypothesis of intramolecular transfer of an acyl group from the ester function in position 8 can be discarded by the observed results.     

Etude par spectrométrie de masse de l'ionisation de benzonitriles,de phénylacétonitriles et de N,N-diméthylanilines substitués

Molecular ionization potentials for series of compounds of the type X? C₆H₄? CN, X? C₆H₄CH₂? CN and X? C₆H₄? N(CH₃)₂ have been measured using the retarding potential difference technique (RPD. technique). The effect of the various substituents X is better correlated through the electrophilic Brown σ_p⁺ constants than through Hammett's σ_p values. No meta-para orientation effect is observed. For all the disubstituted phenyl compounds studied, the effect of the second substituent is affected by the electron-releasing power of the original substituent. Ionization potentials calculated by using the semi-empirical method of equivalent orbitals are in good agreement with the experimental values.     

Interactions Intramolécularies—XVII Calcul des constantes de couplage en RMN du cyclohexane et de cyclohexanes substitués. Comparaison des méthodes de Pople et Santry et des perturbations finies

Proton–proton ³J, ⁴J and ⁵J NMR coupling constants have been calculated for cyclohexane and monosubstituted cyclohexane conformers (substitiuents: Li, CH₃, OH, F) by the two methods mentioned. Comparing the two methods on the basis of group theory, we show the necessity to use the second. The results from this method are compared with those of the literature.     

Etudes RMN en série hétérocyclique. XV—Résonance Magnétique Nucléaire de 1H et de 19F de quelques fluoro-2 benzothiazoles

Chemical shifts and coupling constants of five 2-fluorobenzothiazoles 6-substituted by Me, H, F, Cl and NO₂ are given. A large cross-ring coupling constant (J₂₆ = 10·4 Hz) is found in the 2,6-difluorobenzothiazole.