Photolyse d'oxazirannes: VI—Détermination par RMN du proton des configurations et conformations privilégiées d'oxazirannes à jonction spirannique

The structures of imines and oxaziridines derived from 2-methyl and 2,6-dimethyl cyclohexanone have been determined by ¹H n.m.r. spectroscopy. The preferred conformation of all the oxaziridines we examined was found to have the nitrogen atom in equatorial position.     

Etude par RMN 13C de quelques époxydes exo et endo dans la série du bicyclo[2.2.1]heptane

The ¹³C NMR spectral study of epoxy bicyclo [2.2.1]-heptanes reveals a strong influence on the chemical shift of the bridging ¹³C, due to the endo or exo orientation of the heterocyclic ring. The difference between the ¹³C and ¹H Δδ shows that the observed results cannot be explained by the ring current alone.     

Aziridines N-non substituées: XI—Inversion de l'azote dans des composes C-substitués symetriquement ou non de part et d'autre du cycle

The occurrence of nitrogen inversion in 2- and/or 3-substituted aziridines has been proved by ¹H n.m.r. Only one invertomer was found when the difference in the bulkiness of the substituents on opposite sides of the ring is very great. From the different chemical shifts and the coupling constants of HC? NH one can show that the preferential invertomer, or the only invertomer, is always the one that has the N? H proton on the least hindered ring side. For the symmetrically substituted aziridines the energy barrier measurements have shown a decrease in the energy of the inversion as the steric hindrance of the molecule increases. A new stabilization factor, due to the preferential conformations of the aromatic ring, was found for the invertomers of phenyl substituted aziridines.     

Etude des formes fermées et ouvertes de spiropyrannes benzothiazoliniques en RMN 13C et 1H par transformée de Fourier

Benzothiazolinic spiropyrans, merocyanines and photomerocyanines, thermally stabilised to a high degree, have been studied by means of Fourier transform ¹H and ¹³C NMR. The results show the polarity of open forms such as merocyanines and photomerocyanines, their trans configuration, the alternation of the electronic density on the dimethine bridge between the ‘benzothiazolinic’ and ‘phenolate’ part of these molecules, and also a favoured configuration when photomerocyanines have an alkoxy or aryloxy group on the 3 position.     

Etudes sur les composés organométalliques II [1] Etude spectrophotométrique IR. de quelques complexes de TiCl4 avec la pyridine et des pyridines substituées

The preparation of some complexes of titanium tetrachloride with pyridine and substituted pyridines is described. The IR. spectra of the complexes compared with those of the pure ligands (L) indicate the presence of L→Ti dative bonds in the complexes.     

Etude RMN 13C d'un Dérivé Uniformément Enrichi en 13C. Signe des Valeurs des Constantes de Couplage Observées

The ¹³C NMR parameters of 3-O-acetyl-1,2:5,6-di-O-isopropylidène-α-D-[U-¹³C] glucofuranose, used as a sample for analysis in double labelling biosynthetic experiments, have been measured. Homonuclear double resonance experiments ¹³C? {¹³C} at 62.8 MHz have permitted the determination of all the ¹³C? ¹³C coupling constants. By theoretical computation of spectra, in connection with the second order effects existing at 25.2 MHz and 15.08 MHz, the sign of the coupling constants has been determined. The theoretical computation of spectra took into account all the isotopomers and was calculated with the help of a program (adapted from the LAOCOON program) allowing for the weighted addition of the spectra.     

Nouvelle synthèse des pyrido[4,3-b]quinoléines substituées sur leur sommet 1

A three step synthesis of pyrido[4,3-b]quinolines is reported. Thus, treatment of 2-hydroxy-4-arylaminopyridines under Vilsmeir-Haack conditions directly afforded 1-oxo-1,2-dihydropyrido[4,3-b]quinolines. Chlorination of these compounds gave the corresponding 1-chlorinated derivatives which were then substituted by various primary and secondary amines.     

Etude par RMN du Proton et du Carbone-13 de Pyrimidines Substituées. I—Effets de Substituant dans les Dérivés Méthylés et Aminés

Substituent effects of methyl and amino groups on the chemical shifts of pyrimidine have been investigated by ¹H and ¹³C n.m.r. and compared with similar data obtained for benzene and pyridine. Taking into account pairwise interactions, the chemical shifts calculated by using an additivity relationship are in very good agreement with the experimental results, except for some hindered pyrimidines. This study enabled us to assign the ¹³C n.m.r. spectra of some trisubstituted pyrimidines.     

Synthèse de 5H-isoquino[6, 7-b][1, 6]naphtyridones-12 substituées sur leur sommet 10

Starting from 4-chloronicotinic and derivatives and 6-amino-5-methyl-2H-isoquinolin-1-one, subsequent cyclization of intermediates by sulfuric acid or trifluoromethanesulfonic acid and chlorination by phosphorus oxychloride gave 10-chloro-6-methyl-5H-isoquino[6,6-b][1,6]naphthyridin-12-ones. Cytotoxicity of the corresponding 10-(diethylamino-3)propylamino-6-methyl-5H-isoquino[6,7-b][1,6]naphthyridinh12-ones, compared to that of related 9-azaellipticine derivatives, showed that replacement of pyrrole by a pyridin-4-one nucleus resulted in loss of biological activity.     

Interactions intramoléculaires. XXVII—Etudes structurales en série bicyclo[4.1.0]heptanique (effets d'anisotropie sur les déplacements chimiques du proton; constantes de couplage et équilibres conformationnels)

All the ¹H n.m.r. parameters of the following derivatives of 1,6-dimethylbicyclo[4.1.0]heptane are determined: 3,4-dimethoxycarbonyl (3 diastereoisomers), cis- and trans-3-methoxycarbonyl-2,2,5,5-d₄, cis- and trans-3-methyl-3-methoxycarbonyl; the cis- and trans-1,5,5-trimethylbicyclo[4.1.0]-3-heptanols are studied in the same way. The different chemical shifts are correlated with the aid of a collection of empiral increments. The conformational equilibria are determined from the vicinal coupling constants; the conformational free energies of the COOCH₃ group are evaluated; the part played by gauche interactions is considered.     

Spectres RMN des Polysaccharides et de leurs Dérivés: Influence des Substituants sur le Déplacement Chimique 13C

Methyl and acetyl substituent effects on ¹³C chemical shift have been determined on (α 1→3), (α 1→4), (β 1→3) and (β 1→4) linked polysaccharides such as pseudo-nigerane, β-cyclodextrine, amylose, laminarane and cellulose. Methyl α- and β-D -glucopyranoside have been used as monomer model compounds. Shift determination of hydroxylated and substituted polysaccharides requires unambiguous assignment of their ¹³C spectra. Selective heteronuclear spin decoupling and the isotope effect of deuterated hydroxyl have been used as assignment techniques.     

Etude par RMN 1H d'hétérocycles voisins de l'oxazaphospholane-1,3,2: III—Le phényl-1 dioxa-2,8 aza-5 phosphav-1 bicyclo[3.3.0]octane et le dioxa-1,6 diaza-4,9 phosphav-5 spir[4.4]nonane

The interpretation in terms of conformational analysis of ¹H n.m.r. parameters of 1-phenyl-2,8-dioxa-5-aza-1-phospha^v bicyclo[3.3.0]octane is consistent with a rigid envelope conformation for each 5-membered ring and a planar nitrogen atom. In the case of 1,6-dioxa-4,9-diaza-5-phospha^vspiro[4.4]nonane, the same procedure shows librational motions around the C? C bond.     

Etude du Groupe Azomethine par RMN du Carbone-13. Cétimines et Dibenzo[b,f] diazocines[1,4]

Carbon-13 chemical shifts (substituents effects, variations of shielding and deshielding related to the magnitude of n.π or π.π interactions) not only confirm the non-planar conformation of ketimines of the benzalaniline type, but provide torsional angles of the aromatic rings. Carbon-13 chemical shifts of dibenzo[b,f] diazocines[1,4] confirm the tub-like conformations and the presence of n.π and π.π interactions.     

Influence de la substitution sur la structure de la benzophenone. X.—Etude conformationnelle de benzaldehydes,acetophénones et benzophénones substitués par complexation avec les lanthanides

Low temperature ¹H NMR was unsuccessful in conformational analysis of substituted benzophenones. However, induced lanthanide chemical shifts study permitted us to check satisfactorily the results obtained by Rayleigh depolarised light scattering and dipole moment studies on meta and ortho substituted benzophenones. The existence in solution, of a conformational equilibrium in these cases is confirmed.     

Action de réactifs nucléophiles sur les phényl-5 thiéno[3,2-b]pyrannone-7 et phényl-2 benzo[b]thiéno[3,2-b]pyrannone-4

Reactions of 5-phenylthieno[3,2-b]pyran-7-one, 2-phenylbenzo[b]-thieno[3,2-b]pyran-4-one and the corresponding thiones with sodium ethylate, guanidines, hydrazines and amines are described and compared to those observed with benzopyranones.     

Etude par RMN 13C à 62,89 MHz des branchements éthyles dans les copolymères ethylène-butène et polyéthylène basse densité

Carbon 13 nuclear magnetic resonance spectra (at 62,89 MHz) were obtained for a series of branched heavy alcanes (12-ethyl tricosane, 11,20-diethyl tricontane, 11,18-diethyl octacosane, 11,17-diethyl heptacosane, 11,16-diethyl hexacosane, 9,12-diethyl heneicosane, 5,7-diethyl docosane, 6,7-diethyl docosane, 2 éthyl-hexyl-12 tricosane), which provide a model set for describing the ethyl branched sequences in ethylene butene copolymers and low-density polyethylene (LDPE). For ethylene-butene copolymers we do not detect any head-to-head polymerization of butene as reported recently (the existence of a 1,2-ethyl pair has not been confirmed by the low-field signal at 41,3 ppm), but only isolated ethyl and 1-3-diethyl branches. The three peaks observed in the methyl region (broad signal) of the spectrum are assigned to butene centered triads, as opposed to branches in positions having different tacticities as reported earlier. Carbon 13 nuclear magnetic resonance spectra of high-pressure polymerized low-density polyethylene have been measured at 62,89 MHz. On the basis of Willbourn's double back biting mechanism, two kinds of complex branches, the 1,3-ethyl pair and 2-ethyl-hexyl, have been assigned. Finally, these results suggest that the ethyl branches in low-density polyethylene are not isolated branches.