Etudes d'Hétérocycles Pentagonaux Polyhétéroatomiques par RMN du 13C. Effets de Substituant,de la Benzocondensation et Etude de la Tautomèrie Prototropique en Série Benzothiazolique

The ¹³C NMR spectra of 43 benzothiazoles have been recorded in DMSO-d₆. All carbon atoms have been attributed in an unambigous way owing to substituent effects in position 4, 5, 6 or 7. We discuss variations of chemical shifts as a function of the nature of the substituent in position 2 (equation of type: Δδ = aF+bR+cQ+d′), annelation in the benzoheterocyclic series, and prototropic tautomerism in the benzothiazolic series (in the case of the substituent in the 2-position being an OH, SH or NHR group).     

Stéréochimie de β-diols et de leurs dérivés cycliques—VII. Calcul empirique des déplacements chimiques en série dioxannique. Application a l'analyse conformationnelle de dérivés alkyles

The empirical calculation of chemical shifts of methyl-1,3-dioxans leads to consistent results. Deviations from the experimental value are correlated with ring deformation. This method is applied to 4 or 6-ethyl, -isopropyl and tertiary butyl-1,3-dioxans. With no substituent at C5, the 4-tertiary butyl group causes no more deformation than at the 2 or 5 position. Interactions of this group with one or two methyl groups at C5 are examined.     

Phosphates D'énols: XI—Étude en Spectrométrie de Masse des Dérivés Diméthyliques

The mass spectrometric study of a series of enolic phosphates of type A leades to fragmentation patterns influenced by the nature of the substituents (R, R′ and R″). It is generally observed that a simple or double hydrogen rearrangement occurs with the loss of the enolic groups. When R and R′ are alkyl groups, the migrating groups are the hydrogen atoms on the alkyl group at position 1. When there is no alkyl group at position 1, the hydrogen atoms of the alkyl group at position 2 induce the rearrangement process. Finally, if R, R′ and R″ are hydrogen atoms, the loss of the enolic chain occurs without any rearrangement.     

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.     

Spectres de rotation de la molécule de chlorobenzène : II. Variétés isotopiques multisubstituées et structure géométrique précise

In order to complete the r_s structure of chlorobenzene given in a preceding paper, a variety of isotopic species of this molecule were synthesized and their microwave spectra studied. This made twenty isotopic species available, enabling the determination of the geometrical parameters by a least squares method. Fitting only differences of moments of inertia either for monosubstituted species or to multiply substituted species gave the same result. They hardly differ from the r_o values and agree with the r_s values obtained by the Kraitchman equations. The resulting error limits were reduced, however.

The following structural parameters were obtained, C₁C₂ = 1.399 Å, C₂C₃ = 1.386 Å, C₃C₄ = 1.3976 Å, C₁Cl = 1.7248 Å, C₂H₂ = 1.080 Å, C₃H₃ = 1.081 Å, C₄H₄ = 1.081 Å, C₆C₁C₂ = 120° 16, C₁C₂C₃ = 119°78, C₂C₃C₄ = 120°24, C₃C₄C₅ = 119°80, C₁C₂H₂ = 119°45, C₂C₃H₃ = 119°76.

The structure of the ring differs significantly from C₆ symmetry. The deformation can be regarded as a compression of the position C₁ while the angle of C₂H₂ bond is also changed.     

Étude thermodynamique de la complexation de l''argent par quelques pyrazines substituées

Stability constants of silver complexes with the substituted ligands 2-methyl-2,5-dimethyl-, 2,6-dimethyl-, 2-chloro- and 2-amino-pyrazines are determined by means of a potentiomeric method, using metal complex electrodes at 25°C and 0.1M KNO₃ as an ionic strength in aqueous medium.

Standard enthalpies of the two steps of complexation observed are obtained by a direct calorimetric technique (except for the Ag-2-aminopyrazine system whose complexes are not sufficiently soluble) under the same experimental conditions. The corresponding standard entropies are calculated.

The discussion of the thermodynamic functions takes into account the nature and the position of the substitutents to interprete the coordination ability of each amine.     

Réactions de Friedel et Crafts de dérivés aromatiques sur les composés dioxo-1,4,2,3-non saturés. IV. Réactions des hydroxy-5-ouchloro-5-diméthyl-3,5- ou diméthyl-4,5-dihydro-2,5-furannones-2

Friedel-Crafts reactions of aromatic derivatives with 1,4-dicarbonyls 2,3-éthylenic compounds. Part IV. Reactions of 5-hydroxy or 5-chloro 3,5-dimethyl or 4,5-dimethyl 2 (5 H) furanones We studied the Friedel-Crafts reactions of 2-(5H)-furanones. In the presence of sulfuric acid and of an aromatic derivative, 5-hydroxy- or 5-chloro-5-methyl-2-(5H)-furanones with one methyl group either in the 3 position, or in the 4 position generally give the corresponding 5-aryl-2-(5H)-furanones, while with aluminium chloride, it is possible to obtain, when a reaction takes place, isomeric 1H-indenecarboxylic acids. However, in a particular case, an addition to the substrate's double bond is observed. The 3-aryl-5-hydroxy-tetrahydrofuran-2-one obtained is methylated in two ways and gives either a cyclic product, or a linear one. In two cases tautomerism between 1H-1-indenecarboxylic acid and 1H-3-indenecarboxylic has been shown by ¹H-NMR.     

Structure électronique de dérivés sulfurés : Partie V. spectres électroniques d''hétérocycles thio-carbonylés

The experimental and theoretical spectra of thiocarbonyl heterocyclic compounds with two heteroatoms in the position to the thiocarbonyl group have been studied.

The theoretical interpretation of the CNDO/S results including an extension to the third period, i.e. 3d orbitais, is in good agreement with the saturation effect as well as with the influence of the intracyclic heteroatoms on the typical absorptions of the thiocarbonyl group.     

Stéréochimie de β-diols et de leurs dérivés cycliques–VI. Calcul empirique des déplacements chimiques en série dioxannique. Détermination et discussion des incréments de calcul

In order to calculate empirically proton chemical shifts in methyl 1,3-dioxans, the basic values for each proton of 1,3-dioxan itself are estimated. Then, using methyl derivatives in the chair conformation, the Δδ primary effects of methyl groups in any position are given. Modifications take place in molecules with butane gauche interactions and these secondary effects are evaluated. Analogous Δδ in both the cyclohexane and dioxane series are related to similar cyclic geometry. The presence of oxygen atoms however, introduces important discrepancies.     

Etude par Résonance Magnétique Nucléaire de la thiamine (vitamine B1). Site de protonation-équilibre de tautomérie

Calculations are presented as evidence for the existence of a tautomeric equilibrium in thiamine and its polyphosphoric esters. The relative position of the equilibrium in these compounds is considered. Most of the experimental observations can be explained by the results of the calculations.     

Recherches sur le benzofuranne. LIX. Orientation de l'aroylation de l'éthyl-2 benzofuranne selon la nature du chlorure d'aroyle utilise

While both hindered and unhindered alkanoyl chlorides and some aroyl chlorides react with 2-ethylbenzofuran at the 3 position, most aroyl chlorides also react with 2-ethylbenzofuran at the 6 position and to a lesser extent at the 4 position.     

Nouveaux hétérocycles à partir d'esters cyaniques. Arylimino-2 et arylamino-2 4H-benzoxazin-1,3 ones-4, leur tautomérie et étude de leur alkylation régiosélective

New 2-substituted benzoxazinones have been prepared by reaction of primary aromatic amines with aryl cyanates having an ethoxycarbonyl group in the ortho position By ir and nmr studies, a 2-arylimino-4H-1,3-benzoxazin-4-one structure is assigned to their predominant tautomers. The regioselective synthesis of their alkylated derivatives on the cyclic and exocyclic nitrogens by alkylation in ethanol, dimethylformamide and under sloid-liquid phase transfer conditions has been achieved     

Etude en RMN de l'Association des Sels de Lanthanides avec des Phénols; Application à la Détermination de Structure de Polyphénols Naturels

Interaction of lanthanide salts with phenols in DMSO solution was investigated as a tool for ¹H NMR structure determination in the field of naturally-occurring polyphenolic compounds. Intermolecular competition experiments evidenced reactivity differences with respect to the nature and position of substituents. Empirical rules of reactivity are suggested from which variations observed in the PMR chemical shifts on addition of lanthanide salts to natural polyphenols (flavones, xanthones) were rationalized.     

Etude par RMN. de polyaminocarboxylates de terres rares,III. Hydroxyéthyliminodiacétates de praséodyme

¹H—NMR. has been used to study the chemistry of the hydroxyethyliminodiacetate complexes of praseodymium in aqueous solution. The ligand exchanges by spontaneous dissociation of the metal-bis-hydroxyethyliminodiacetate (1:2 complex) and of the metal-bis-hydroxyethyliminodiacetate hydroxocomplex, by acid catalysed dissociation of the 1:2 complex, and by a bimolecular process involving the free ligand and the 1:2 complex or the ternary hydroxo-complex. The ligand exchange rate constants are given and the mechanisms discussed.     

Diénamines hétérocycliques. III. Réexamen de la réaction de la base de Fischer avec le tétracyanoéthylène

Heterocyclic dienamines III. A re-examination of the reaction of Fischer's base on tetracyanoethylene Depending on the order of addition, Fischer's base 5 (1,3,3-trimethyl-2-methylidene-indoline) reacts 1:1 with tetracyanoethylene to give either the tricyanovinylation product 6 or the spiro compound 7 . A skeletal rearrangement of a zwitterionic intermediate can explain the formation of the spiro compound. The latter undergoes a thermal isomerization yielding by ring expansion the tetrahydroquinoléine 8 . On reaction with LiAlH₄ or CH₃ONa 7 and 8 lead both to triazatetracycles. All structures are assigned on the basis of spectral data.     

Etude des voies d'accès aux aminométhyl benzo[g]isoquinoléinediones-5,10. Mise en évidence d'une substitution anormale au cours de la réaction de Bischler-Napieralski en série diméthoxy-1,4 naphthalène

Under the conditions of the Bischler-Napieralski reaction the cyclization of 2-(1,4-dimethoxy and 1,4,8-trimethoxynaphthyl)ethylacetamides derivatives take place essentially at the 1 position by substitution of the 1-methoxy group. Nevertheless, 1-aminomethyl-9,10-azaanthraquinones are accessibles by condensation of 1-aminomethylisoquinoline-5,8-diones with a 1,4-diacetoxy-1,3-butadiene.     

Substitution électrophile aromatique dans l'anhydride sulfureux liquide. Etude cinétique de la réaction de bromation d'anisoles monosubstitués. Transmission des effets électroniques et caractéristiques de l'état de transition

Reactivity-structure correlations for anisole and eleven of its substituted derivatives established from bromination rate constants in liquid SO₂, unlike observations in water, show the reaction to be highly sensitive to substituent effects, (ρ = ?7.1; ρ = ?10.51). This result is ascribed to the solvation of the methoxy group which decreases the conjugation of para-substituted (ρ = ?9.70) compared to that of ortho-substituted derivatives (ρ = ?8.86). The highly solvated transition state lies far from reactants on the reaction coordinate and the positive charge developed in this state is nearly unity.     

Nouveaux exemples de radicaux libres stables de dérivés hétérocycliques de sucres. Communication préliminaire

Some more examples of stable free radicals of carbohydrate heterocyclic derivatives 2-Glycosyl-4,4,5,5-tetramethylimidazoline- 3-oxide-1-oxyls and 2-glycosyl-4,4,5,5-tetramethylimidazoline 1-oxyls have been prepared in nine carbohydrate series, which proves the generality of the method. The hyperfine coupling constant between the free electron and the α-proton of the glycosyl group is never very large (0-2.3 G) but a correlation between its value and the structure of the aglycone has been noted. Free radicals of that type, stable in aqueous solutions, are potentially interesting for biological studies.     

Recherches en série diazépine-1,4 et triazépine-1,2,4. X. Réductions et méthylations de pyrazolo[3,4-b]diazépines-1,4

Reduction and methylation of pyrazolo[ 3,4-b ]diazepines have been effected by several methods. According to the reducing agents used, it has been possible to reduce selectively the C?N double bond, the carbonyl group, to reduce the diazepinone rings completely and to reduce partially or completely the insaturated parts of the (6H)pyrazolodiazepines. Methylation on the amide nitrogen, on oxygen of the same function, and in a few cases on the C₆ carbon of the pyrazolodiazepinones and finally on the 4 position in tetrahydropyrazolodiazepinones have been obtained.     

Sur l'orientation de la nitration des nitriles et amides coumariliques Bz-méthoxylés

Direct nitrations of 2-carboxamido- and 2-cyano-Bz-methoxybenzofurans by nitric acid in acetic anhydride always yiels two derivatives nitrated on the homocyclic ring at the ortho or, possibly, the para position to the methoxyl group. The proportions vary with the case in question. The methoxylated nitrocarboxamides and nitronitrilies obtained can be demethylated nitrocarboxamides and nitronitriles obtained can demethylated by pridinium chloride. Their hydrokysis into the corresponding acids is performed without demethylation by diluted sulfuric acid and, except in one case, with simulatenous demethylation by dilued soda.