Showing papers by "José Elguero published in 1975"
TL;DR: In this article, the barrier to internal rotation about the NC bond and the E/Z configuration of some N-acetyl and N-formylindole derivatives have been determined and discussed in terms of electronic and steric effects.
Abstract: The barrier to internal rotation about the NC bond and the E/Z configuration of some N-acetyl and N-formylindole derivatives have been determined and discussed in terms of electronic and steric effects. The barriers to internal rotation have been determined for certain N-acetylcarbazoles and some new N-formyl derivatives of carbazole. Experimental proof is also given, showing that contrary to the provisions of the classical model of carbonyl anisotropy, the protons (α and peri positions) next to the oxygen of the acyl group are displaced to high frequencies. This result allows one to determine the preferred configuration of N-acetyl derivatives of perimidine and 1H-naphtho[1,8-de]triazine.
23 citations
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TL;DR: Carbon-13 and deuterium labelling experiments show that the [M CH3]+ ion observed in the mass spectrum of l-ethylbenzimidazole rearranges quantitatively to a quinoxalinium structure prior to HCN loss as mentioned in this paper.
Abstract: Par marquages isotopiques (13C et D), on montre que l'ion [M CH3]+ observe dans le spectre de masse du l-ethylbenzimidazole se rearrange quantitativement en une structure quinoxalinium avant l'elimination d'acide cyanhydrique.
Carbon-13 and deuterium labelling experiments show that the [M CH3]+ ion observed in the mass spectrum of l-ethylbenzimidazole rearranges quantitatively to a quinoxalinium structure prior to HCN loss.
12 citations
11 citations
TL;DR: In this paper, the methode CNDO/2 avec optimisation de l'ensemble des parametres geometriques a ete appliquee avec succes a l'etude de la protonation des enamines.
Abstract: La methode CNDO/2 avec optimisation de l’ensemble des parametres geometriques a ete appliquee avec succes a l’etude de la protonation des enamines. Elle permet d’expliquer d’une maniere satisfaisante l’aspect thermodynamique du probleme : equilibres enamine-imine et sel d’immonium-sel d’enamonium. Elle apporte des renseignements sur le mecanisme de la N-protonation (origine de l’energie d’activation, chemin d’approche du proton). Pour la C-protonation elle montre que ce n’est pas le proton qui se fixe sur le carbone (ni intra ni intermoleculairement) mais une entite protonique differente.
9 citations
TL;DR: In this paper, the authors danken der Deutschen Forschungsgemeinschaft und dem Fonds der Chemischen Industrie fur die Forderung dieser Arbeit.
4 citations
TL;DR: In this paper, the proton NMR spectra of certain arylhydroxylamines in DMSO-d6 show a vicinal coupling through nitrogen and oxygen.
Abstract: The proton NMR spectra of certain arylhydroxylamines in DMSO-d6 show a vicinal coupling through nitrogen and oxygen. The assignment of OH and NH signals was made using a 15N labelled derivative.
2 citations