Josanton Artze “Harzabal”: inguruaren eragina poesiagintzan (1969-1979)

503 p. (Blbliogr. 485-503)

Activación de aldehídos a,b-insaturados mediante aminocatálisis en procesos enantioselectivos. Cicloadiciones (3+2) y reacciones en cascada Michael/Henry

During the research that it is summarized in the present memory, the activation of enals via iminium ion catalysis in different transformations has been studied. Firstly, a 1,3-dipolar cycloaddition between stable azomethine ylides and a,b-unsaturated aldehydes catalyzed by a chiral imidazolidinone derivative has been optimized. Employing this methodology we have synthesized a large range of densely substituted pyrroloisoquinolines and pyrrolophthalazines with good yields and high values of diastereo- and enantioselectivity. Moreover, a mechanistic study has been carried out based on DFT calculations and experimental data which have allowed us to propose that the (3+2) cycloaddition reaction follows a sequential Michael addition/Mannich cyclization pathway. The formation of the iminium ion as a result of the condensation between the a,b-unsaturated aldehyde and the catalyst plays an essential role, regarding both reactivity and stereoselectivity. On the other hand we have developed a methodology to carry out a cascade Michael/Henry reaction followed by a sequential dehydration. Starting from simple substrates (2-nitromethylacrilates and a,b-unsaturated aldehydes) and employing a prolinol-derivative catalyst a series of quiral nitrocyclohexadienes have been synthesized.

Nuevos datos sobre la estela romana de Puebla de Azaba (Ciudad Rodrigo, Salamanca)

[ES] Damos a conocer la forma y el texto completos de la inscripción de referencia con descubrimiento de tres nuevas líneas de texto y elementos decorativos astrales en cabecera semicircular. En estas líneas se encuentran dos "cognomina" indígenas de la zona de los verrones, uno muy abundante ("Arco") y el otro menos frecuente ("Taginus").