Etude par RMN 1H des effets de solvant sur les déplacements chimiques et les couplages vincinaux des benzothiénopyridines

The solvent/solute interactions of four isomeric benzothienopyridines (parent compounds) have been investigated by ¹H n.m.r. A close study of the second-order spectra shows: (i) a preferential orientation of the solvent molecules (acetone) surrounding the pyridine ring; (ii) large variations in the coupling constants of the benzenic part of the benzothienopyridines as a function of the solvent; (iii) a preferential interaction of the pyridine ring in collision complexes with benzene. These results can be applied to a comparative study of the complexes between DNA base pairs and intercalating derivatives.     

Utilisation des déplacements chimiques induits par les lanthanides a la détermination de la structure de benzothiénopyridines

Lanthanide-induced shifts provide a convenient method for total assignment of ¹H nmr spectra of benzothienopyridines and determination of the substitution sites. Evidence of the effect of steric hindrance around the site of complex formation on the spatial localization of the lanthanide ion is given.     

Etude théorique des déplacements chimiques du phosphore en RMN

Phosphorus chemical shifts have been evaluated by means of the perturbation theory using CNDO/S wave functions in phosphine, phosphite, phosphonate and phosphate derivatives. The necessity of introducing 3d orbitals of phosphorus and of using Z_eff3d as an adjustable parameter for each family of compounds is shown. Calculated values agree with experimental ones.     

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.     

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.     

Etudes par la RMN du carbone-13 de quelques dérivés cyclopropaniques: Déplacements chimiques et paramètres structuraux

Measurements of the ¹³C chemical shifts of monosubstituted cyclopropanes (C₃H₅X, X = CH₃, Br, ? C?CH) enabled us to determine the direct additivity parameters which depend solely on the nature of the substituent. In the case of polysubstituted derivatives, complementary effects due to pairwise contributions of the substituents superpose upon the direct effects. A systematic study of cyclopropanes polysubstituted by bromine atoms, and methyl and ethynyl groups shows these different contributions and permits us to propose a simple interpretation for the majority of cases. Pairwise interaction has been ascribed either to electron transfer or to symmetric or dissymmetric steric interactions between the different substituents, as is shown by the comparison of the theoretical with the experimental shift values.     

Spectre RMN 1H et 13C de tous les mono- et diacétoxynaphtalènes. Increments de déplacement chimique pour le proton et le carbone-13. Cas de quelques autres dérivés du naphtalène

The study of this series of compounds proves the usefulness of shift increments for the identification of proton and carbon-13 resonances. These increments may be obtained as a first approximation from the study of the monosubstituted derivatives or by comparison with the corresponding benzene derivatives.     

Sur les complexes formés par le trifluorure de bore avec les sulfoxydes,aminoxydes, phosphinoxydes et arsinoxyde: Aspects généraux des spectres de RMN (1H, 11B, 19F et 31P)

Various complexes (R_nMO·BF₃) of boron trifluoride with sulphoxides, aminoxides, phosphinoxides and arsinoxides have been prepared and investigated using proton, fluorine (at variable temperature) boron and phosphorus resonance. A comparison with similar adducts containing a co-ordinative O? B bond is presented.     

De la chimie des ptérines. 19e communication [1]. Essai d'interprétation des propriétés chimiques des ptérines au moyen de calcul d'orbitales moléculaires

HMO and semi-empirical SCF calculations on pterine systems of biochemical interest have been performed. The most basic center of each molecule has been determined by correlating the perturbation effect on the transition energy and the spectroscopic data. Additional calculations attempt to show why the redox-system which interfers in hydroxylation reactions consists of 5,6,7,8-tetrahydropterine and a quinoidic form. Finally the formation of radicals in the oxidation step of hydrogenated pterines is discussed.     

Epoxydes cyclopentaniques conformationnellement homogènes. II—Détermination des configurations au moyen des déplacements chimiques induits par compléxation a l'Europium

The configuration of conformationally homogeneous epoxides in trans bicyclo-(n.3.0) alkanes is established by progressive complexation with Eu(dpm)₃. The examples described demonstrate the importance of this method which is superior to all the other physicochemical methods already used to determine the cyclopentane epoxide configuration.     

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.     

Etude du mécanisme de la réaction de hantzsch des thiazoles. I. Mise en évidence et détermination des produits intermédiaires et de dégradation

The Hantzsch thiazole synthesis from α-haloketones and thioamides, proceeds via intermediates that can be isolated under certain conditions. These have been identified, mainly by nmr spectroscopy, as thioimidate derivatives. The chain or cyclic structures of these compounds depend upon the nature of the substituents. Their dehydration gives together with the expected thiazole, secondary products which have also been isolated and identified as α-mercaptoketones and α-ketothiolesters.     

Etude cinétique des effets de fluence énergétique,de débit de fluence,et d'effacement induits par des ions lourds et des photons γ dans le triacétate de cellulose

The kinetic interpretation of the damage produced by heavy ions (Kr and Cl from 1 MeV/amu) and γ radiation in cellulose triacetate leads to an exponential dependence on the ion fluence. A comparison of the fading effect produced by heavy ions and γ rays shows that the heavy ions, unlike γ rays, cause irreversible damage. Finally, a nonlinear dependence on the flux of ions and γ rays is found in the kinetics of radiation damage. This result is contrary to the usual assumption that heavy-ion flux, like γ-ray flux, is additive, at least for the fluxes of 10⁹?2 × 10¹⁰ ions/cm²s and dose rates of 10³–10⁴ Gy/h used in this work.     

Utilisation des déplacements chimiques induits par les lanthanides dans l'analyse conformationnelle d'hétérocycles aromatiques β-carbonylés

The preferential conformation of 3-formyl and 3-acetyl furans, thiophenes, pyrroles and some 3-acyl furans are determined by use of simulated lanthanide induced shifts. The ratios of the different rotamers are similar to those obtained by other n.m.r. methods. This result shows that the complexation does not induce any change in the conformational preference, and thus validates the use of the foregoing method for the conformational analysis of heteroaromatic aldehydes and ketones. In the three heterocycles studied, the carbonyl group shows an X? O trans preferential conformation for the aldehydes and a mixed equilibrium in the case of acetyl groups.     

Sur le calcul du P K des premiers états excités singulet et triplet du β naphtol et de la β naphtylamine

Résumé En suivant la méthode dite du «cycle de Förster», on détermine au moyen des méthodes de la Chimie Quantique les valeurs des P _K des états excités singulet et triplet de la -naphtylamine et du -naphtol. Dans le cas de cette dernière molécule, on propose un modèle pour décrire l'ion -naphtolate intervenant dans les équilibres classiques étudiés.

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Calculation of the P _k values of the first excited singlet and triplet states of -naphthol and -naphthylamine

On the basis of the cycle of Förster the P _K values of the excited singlet and triplet states of -naphthylamine and -naphthol are determined. In the case of the latter molecule a model is proposed in order to calculate the anion of -naphthol, which is found in classical equilibriums.

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Zusammenfassung Ausgehend vom Försterzyklus werden auf quantenmechanische Weise die P _K -Werte der angeregten Singulett- und Triplettzustände des -Naphthylamins und des -Naphthols bestimmt. Im Fall des letzteren Moleküls wird ein Modell zu Berechnung des -Naphtholations, das bei dem untersuchten Gleichgewicht auftritt, vorgeschlagen.

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J. J. Dannenberg tient à remercier le National Institute of General Medical Science de l'attribution d'une bourse post-doctorale.     

Sur les dérivés de la fluorénone VII. Bifluorényles et bifluorénonyles

Starting from 3-bromo-, 1-iodo- and 4-iodo-9-oxo-fluorene three symmetrical bifluorenonyls and the corresponding hydrocarbons 3,3′-, 1,1′- and 4,4′-bifluorenyls are prepared. An attempt to obtain the non-symmetrical 1,2′-bifluorenyl is also described.