FQM339 - Artículos
https://hdl.handle.net/10481/29458
2024-03-29T10:36:13ZOctagon-Embedded Carbohelicene as a Chiral Motif for Circularly Polarized Luminescence Emission of Saddle-Helix Nanographenes
https://hdl.handle.net/10481/78152
Octagon-Embedded Carbohelicene as a Chiral Motif for Circularly Polarized Luminescence Emission of Saddle-Helix Nanographenes
Medel Miranda, Miguel Ángel; Tapia Martín, Rubén; Blanco Suárez, Víctor; Miguel Álvarez, Delia; Morcillo Martínez, Sara Patricia; González Campaña, Araceli
We report a new family of hexa-peri-hexabenzocoronene (HBC)-based helical nanographenes incorporating π-extended carbo[5]helicenes bearing an octagonal carbocycle. This family represents a new kind of highly distorted saddle-helix hybrid nanographenes. For the first time, the eight-membered ring becomes a constituent of both a carbo[5]helicene and a HBC and thus, the negative curvature is responsible for twisting both units. This novel chiral motif, namely, oct-[5]helicene results in the largest torsion angle recorded so far for a carbo[5]helicene (θ=79.5°), as it has been suggested by DFT-calculations and confirmed by X-ray crystallography. Consequently, the barriers of isomerization become exceptionally high for a [5]helicene unsubstituted in the fjord region since neither racemization nor decomposition were observed at 200 °C for 1 or 3 during 5 h. Therefore, racemic resolutions allowed subsequent chiroptical studies showing the ECD and CPL responses of this novel family of chiral nanographenes.
Aproximación a la síntesis enantioselectiva de achillifolina
https://hdl.handle.net/10481/58377
Aproximación a la síntesis enantioselectiva de achillifolina
Rosales, Antonio; Muñoz Bascón, Juan; Castilla Alcalá, José Antonio; Roldán Molina, Esther; Olmedo, Santiago; Proaño, Janeth; Oltra Ferrero, Juan Enrique
En este artículo se presenta una aproximación biomimética a la síntesis enantioselectiva de
achillifolina, una lactona sesquiterpénica natural aislada de Achillea millefolium subsp. Millenium.
La ciclación carbocatiónica de epoxi-costunolida es la etapa clave de la secuencia sintética. Esta
ciclación transanular permite la formación del esqueleto de 1,4-epoxi-ciclodecano presente en
(+)-achillifolina.; In this paper, an approximation biomimetic synthesis of achillifoline, a natural sesquiterpene lactone
isolated from Achillea millefolium subsp. Millenium, is presented. Carbocationic cyclization of epoxycostunolide is the key step of the synthetic sequence. This transannular cyclization, allows the
formation of the skeleton of 1,4-epoxy-cyclodecane presents in achillifoline.